# How to use Ghostscript

## Table of contents

> - Invoking Ghostscript
>   - Help at the command line: `gs -h`
> - Selecting an output device
>   - Output resolution
>   - Output to files
>     - One page per file
>   - Choosing paper size
>   - Changing the installed default paper size
> - Interacting with pipes
> - Using Ghostscript with PDF files
>   - Switches for PDF files
>   - Problems interpreting a PDF file
>   - PDF files from standard input
> - Using Ghostscript with EPS files
> - Using Ghostscript with overprinting and spot colors
> - How Ghostscript finds files
>   - Finding PostScript Level 2 resources
>   - Font lookup
>   - CID fonts
>   - CID font substitution
>   - Temporary files
> - Notes on specific platforms
>   - Unix
>   - VMS
>     - Using X Windows on VMS
>   - MS Windows
>   - X Windows
>     - X resources
>     - Working around bugs in X servers
>     - X fonts
>     - Using Ghostscript fonts on X displays
>     - X device parameters
>   - SCO Unix
> - Command line options
>   - General switches
>     - Input control
>     - File searching
>     - Setting parameters
>     - Suppress messages
>   - Parameter switches (`-d` and `-s`)
>     - Rendering parameters
>     - Page parameters
>     - Font-related parameters
>     - Resource-related parameters
>     - Interaction-related parameters
>     - Device and output selection parameters
>     - EPS parameters
>     - Other parameters
> - Improving performance
> - Summary of environment variables
> - Debugging
>   - Debug Switches
>   - Visual Trace
> - Appendix: Paper sizes known to Ghostscript
> - Appendix: X default font mappings
>   - Standard X servers
>     - Regular fonts
>     - Symbol fonts
>     - Dingbat fonts
>   - Sun OpenWindows
> - Appendix: Running Ghostscript with 3d party font renderers

For other information, see the Ghostscript overview and, if necessary, how to install Ghostscript.

## Invoking Ghostscript

This document describes how to use the command line Ghostscript client. Ghostscript is also used as a general engine inside other applications (for viewing files for example). Please refer to the documentation for those applications for using Ghostscript in other contexts.

The command line to invoke Ghostscript is essentially the same on all systems, although the name of the executable program itself may differ among systems. For instance, to invoke Ghostscript on unix-like systems type:

>     gs [options] {filename 1} ... [options] {filename N} ...

Here are some basic examples. The details of how these work are described below.

To view a file:

>     gs -dSAFER -dBATCH document.pdf

You'll be prompted to press return between pages.

To convert a figure to an image file:

>     gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=png16m -dGraphicsAlphaBits=4 \
>         -sOutputFile=tiger.png tiger.eps

To render the same image at 300 dpi:

>     gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=png16m -r300 \
>                     -sOutputFile=tiger_300.png tiger.eps

To render a figure in grayscale:

>     gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=pnggray -sOutputFile=figure.png figure.pdf

To rasterize a whole document:

>     gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=pgmraw -r150 \
>                     -dTextAlphaBits=4 -sOutputFile='paper-%00d.pgm' paper.ps

There are also a number of utility scripts for common to convert a PostScript document to PDF:

>     ps2pdf file.ps

The output is saved as file.pdf.

There are other utility scripts besides `ps2pdf`, including `pdf2ps`, `ps2epsi`, `pdf2dsc`, `ps2ascii`, `ps2ps` and `ps2ps2`. These just call Ghostscript with the appropriate (if complicated) set of options. You can use the 'ps2' set with eps files.

Ghostscript is capable of interpreting PostScript, encapsulated PostScript (EPS), DOS EPS (EPSF), and Adobe Portable Document Format (PDF). The interpreter reads and executes the files in sequence, using the method described under "File searching" to find them.

The interpreter runs in interactive mode by default. After processing the files given on the command line (if any) it reads further lines of PostScript language commands from the primary input stream, normally the keyboard, interpreting each line separately. To quit the interpreter, type "`quit`". The `-dBATCH -dNOPAUSE` options in the examples above disable the interactive prompting. The interpreter also quits gracefully if it encounters end-of-file or control-C.

The interpreter recognizes many options. An option may appear anywhere in the command line, and applies to all files named after it on the line. Many of them include "`=`" followed by a parameter. The most important are described in detail here. Please see the reference sections on options and devices for a more complete listing.

### Help at the command line: `gs -h`

You can get a brief help message by invoking Ghostscript with the `-h` or `-?` switch, like this:

>     gs -h
>     gs -?

The message shows for that version of the Ghostscript executable:

- the version and release information
- the general format of the command line
- a few of the most useful options
- the formats it can interpret
- the available output devices
- the search path
- the bug report address

On other systems the executable may have a different name:

> System |  | invocation name
> --- | --- | ---
> Unix |  | `gs`
> VMS |  | `gs`
> MS Windows 95 and later |  | `gswin32c`
> MS Windows 3.1/Win32s |  | `gswin32`
> OS/2 |  | `gsos2`

## Selecting an output device

Ghostscript has a notion of 'output devices' which handle saving or displaying the results in a particular format. Ghostscript comes with a diverse variety of such devices supporting vector and raster file output, screen display, driving various printers and communicating with other applications.

The command line option '`-sDEVICE=`device' selects which output device Ghostscript should use. If this option isn't given the default device (usually a display device) is used. Ghostscript's built-in help message (`gs -h`) lists the available output devices. For complete description of the devices distributed with Ghostscript and their options, please see the devices section of the documentation.

Note that this switch must precede the name of the first input file, and only its first use has any effect. For example, for printer output in a configuration that includes an Epson printer driver, instead of just `'gs myfile.ps'` you might use

> `gs -sDEVICE=epson myfile.ps`

The output device can also be set through the `GS_DEVICE` environment variable.

Once you invoke Ghostscript you can also find out what devices are available by typing '`devicenames ==`' at the interactive prompt. You can set the output device and process a file from the interactive prompt as well:

>     (epson) selectdevice
>     (myfile.ps) run

All output then goes to the Epson printer instead of the display until you do something to change devices. You can switch devices at any time by using the `selectdevice` procedure, for instance like one of these:

>     (x11alpha) selectdevice
>     (epson) selectdevice

### Output resolution

Some printers can print at several different resolutions, letting you balance resolution against printing speed. To select the resolution on such a printer, use the `-r` switch:

> `gs -sDEVICE=`printer`-r` XRES `x` YRES

where XRES and YRES are the requested number of dots (or pixels) per inch. Where the two resolutions are same, as is the common case, you can simply use `-r` res.

The `-r` option is also useful for controlling the density of pixels when rasterizing to an image file. It is used this way in the examples at the beginning of this document.

### Output to files

Ghostscript also allows you to control where it sends its output. With a display device this isn't necessary as the device handles presenting the output on screen internally. Some specialized printer drivers operate this way as well, but most devices are general and need to be directed to a particular file or printer.

To send the output to a file, use the `-sOutputFile=` switch or the `-o` switch (below). For instance, to direct all output into the file `ABC.xyz`, use

> `gs -sOutputFile=ABC.xyz`

When printing on MS Windows systems, output normally goes directly to the printer, `PRN`. On Unix and VMS systems it normally goes to a temporary file which is sent to the printer in a separate step. When using Ghostscript as a file rasterizer (converting PostScript or PDF to a raster image format) you will of course want to specify an appropriately named file for the output.

Ghostscript also accepts the special filename '`-`' which indicates the output should be written to standard output (the command shell).

Be aware that filenames beginning with the character `%` have a special meaning in PostScript. If you need to specify a file name that actually begins with `%`, you must prepend the `%os%` filedevice explicitly. For example to output to a file named `%abc`, you need to specify

> `gs -sOutputFile=%os%%abc`

Please see Ghostscript and the PostScript Language and the PostScript Language Reference Manual for more details on `%` and filedevices.

Note that on MS Windows systems, the `%` character also has a special meaning for the command processor (shell), so you will have to double it:

> `gs -sOutputFile=%%os%%%%abc` (on MS Windows)

#### One page per file

Specifying a single output file works fine for printing and rasterizing figures, but sometimes you want images of each page of a multi-page document. You can tell Ghostscript to put each page of output in a series of similarly named files. To do this place a template '`%d`' in the filename which Ghostscript will replace with the page number.

Note: Since the `%` character is used to precede the page number format specification, in order to represent a file name that contains a `%`, double `%` characters must be used. For example for the file `my%foo` the OutputFile string needs to be `my%%foo`.

The format can in fact be more involved than a simple '`%d`'. The format specifier is of a form similar to the C `printf` format. The general form supported is:

                %[flags][width][.precision][l]type

        where:  flags    is one of:  #+-
                type     is one of:  diuoxX

For more information, please refer to documentation on the C printf format specifications. Some examples are:

> `-sOutputFile=ABC-%d.png`
>   produces '`ABC-1.png`', ... , '`ABC-10.png`', ...

> `-sOutputFile=ABC-%03d.pgm`
>   produces '`ABC-001.pgm`', ... , '`ABC-010.pgm`', ...

> `-sOutputFile=ABC_p%04d.tiff`
>   produces '`ABC_p0001.tiff`', ... , '`ABC_p0510.tiff`', ... , '`ABC_p5238.tiff`'

Note however that the one page per file feature is not supported by all devices; in particular it does not work with document-oriented output devices like `pdfwrite` and `pswrite`. See the `-dFirstPage` and `-dLastPage` switches below for a way to extract single pdf pages.

As noted above, when using MS Windows console (command.com or cmd.exe), you will have to double the `%` character since the `%` is used by that shell to prefix variables for substitution, e.g.,

> `gswin32c -sOutputFile=ABC%%03d.xyz`

#### -o option:

As a convenient shorthand you can use the `-o` option followed by the output file specification as discussed above. The `-o` option also sets the `-dBATCH` and `-dNOPAUSE` options. This is intended to be a quick way to invoke ghostscript to convert one or more input files. For instance, to convert somefile.ps to JPEG image files, one per page, use:

> `gs -sDEVICE=jpeg -o out-%d.jpg somefile.ps`

is equivalent to:

> `gs -sDEVICE=jpeg -sOutputFile=out-%d.jpg -dBATCH -dNOPAUSE somefile.ps`

### Choosing paper size

Ghostscript is distributed configured to use U.S. letter paper as its default page size. There are two ways to select other paper sizes from the command line:

- If the desired paper size is listed in the section on paper sizes known to Ghostscript below, you can select it as the default paper size for a single invocation of Ghostscript by using the `-sPAPERSIZE=` switch, for instance

  > `-sPAPERSIZE=a4
  > -sPAPERSIZE=legal`

- Otherwise you can set the page size using the pair of switches

  > `-dDEVICEWIDTHPOINTS=`w `-dDEVICEHEIGHTPOINTS=`h

  Where w be the desired paper width and h be the desired paper height in points (units of 1/72 of an inch).

Individual documents can (and often do) specify a paper size, which takes precedence over the default size. To force a specific paper size and ignore the paper size specified in the document, select a paper size as just described, and also include the `-dFIXEDMEDIA` switch on the command line.

The default set of paper sizes will be included in the `currentpagedevice` in the `InputAttributes` dictionary with each paper size as one of the entries. The last entry in the dictionary (which has numeric keys) is a non-standard (Ghostscript extension) type of PageSize where the array has four elements rather than the standard two elements. This four element array represents a page size range where the first two elements are the lower bound of the range and the second two are the upper bound. By default these are [0, 0] for the lower bound and [16#fffff, 16#fffff] for the upper bound.
The range type of PageSize is intended to allow flexible page size sepcification for non-printer file formats such as JPEG, PNG, TIFF, EPS, ...
For actual printers, either the entire `InputAttributes` dictionary should be replaced or the range type entry should not be included. To simplify using the default page sizes in the `InputAttributes` dictionary, the command line option `-dNORANGEPAGESIZE` can be used. Using this option will result in automatic rotation of the document page if the requested page size matches one of the default page sizes.

### Changing the installed default paper size

You can change the installed default paper size on an installed version of Ghostscript, by editing the initialization file `gs_init.ps`. This file is usually in the `lib` directory somewhere in the search path. See the section on finding files for details.

Find the line

>     % /DEFAULTPAPERSIZE (a4) def

Then to make A4 the default paper size, uncomment the line to change this to

>     /DEFAULTPAPERSIZE (a4) def

For `a4` you can substitute any paper size Ghostscript knows.

This supecedes the previous method of uncommenting the line `% (a4) ...`.

Sometimes the initialization files are compiled into Ghostscript and cannot be changed.

## Interacting with pipes

As noted above, input files are normally specified on the command line. However, one can also "pipe" input into Ghostscript from another program by using the special file name '`-`' which is interpreted as standard input. Examples:

> {some program producing ps} `| gs` [options] `-`
> `zcat paper.ps.gz` `| gs` `-`

Ghostscript cannot read PDF files from standard input or a pipe because the PDF language inherently requires random access to the file. Thus '`-`' only works with PostScript documents.

When Ghostscript finishes reading from the pipe, it quits rather than going into interactive mode. Because of this, options and files after the '`-`' in the command line will be ignored.

On Unix and MS Windows systems you can send output to a pipe in the same way. For example, to pipe the output to `lpr`, use the command

> `gs -q -sOutputFile=- | lpr`

In this case you must also use the `-q` switch to prevent Ghostscript from writing messages to standard output which become mixed with the intended output stream.

Similar results can be obtained with the `%stdout` and `%pipe%` filedevices. The example above would become

> `gs -sOutputFile=%stdout -q | lpr`

or

> `gs -sOutputFile=%pipe%lpr`

(again, doubling the `%` character on MS Windows systems.)

In the last case, `-q` isn't necessary since Ghostscript handles the pipe itself and messages sent to stdout will be printed as normal.

## Using Ghostscript with PDF files

Ghostscript is normally built to interpret both PostScript and PDF files, examining each file to determine automatically whether its contents are PDF or PostScript. All the normal switches and procedures for interpreting PostScript files also apply to PDF files, with a few exceptions. In addition, the `pdf2ps` utility uses Ghostscript to convert PDF to (Level 2) PostScript.

### Switches for PDF files

Here are some command line options specific to PDF

`-dFirstPage=`pagenumber
  Begins interpreting on the designated page of the document.

`-dLastPage=`pagenumber
  Stops interpreting after the designated page of the document.

`-dPDFFitPage`
  Rather than selecting a PageSize given by the PDF MediaBox or CropBox (see -dUseCropBox), the PDF file will be scaled to fit the current device page size (usually the default page size).

  This is useful to avoid clipping information on a PDF document when sending to a printer that may have unprintable areas at the edge of the media larger than allowed for in the document.

  This is also useful for creating fixed size images of PDF files that may have a variety of page sizes, for example thumbnail images.

`-dPrinted`
`-dPrinted=false`
  Determines whether the file should be displayed or printed using the "screen" or "printer" options for annotations and images. With `-dPrinted`, the output will use the file's "print" options; with `-dPrinted=false`, the output will use the file's "screen" options. If neither of these is specified, the output will use the screen options for any output device that doesn't have an `OutputFile` parameter, and the printer options for devices that do have this parameter.

`-dUseCropBox`
  Sets the page size to the CropBox rather than the MediaBox. Some files have a CropBox that is smaller than the MediaBox and may include white space, registration or cutting marks outside the CropBox. Using this option will set the page size appropriately for a viewer.

`-sPDFPassword=`password
  Sets the user or owner password to be used in decoding encrypted PDF files.

### Problems interpreting a PDF file

Occasionally you may try to read or print a 'PDF' file that Ghostscript doesn't recognize as PDF, even though the same file can be opened and interpreted by an Adobe Acrobat viewer. In many cases, this is because of incorrectly generated PDF. Acrobat tends to be very forgiving of invalid PDF files. Ghostscript tends to expect files to conform to the standard. For example, even though valid PDF files must begin with `%PDF`, Acrobat will scan the first 1000 bytes or so for this string, and ignore any preceding garbage.

In the past, Ghostscript's policy has been to simply fail with an error message when confronted with these files. This policy has, no doubt, encouraged PDF generators to be more careful. However, we now recognize that this behavior is not very friendly for people who just want to use Ghostscript to view or print PDF files. Our new policy is to try to render broken PDF's, and also to print a warning, so that Ghostscript is still useful as a sanity-check for invalid files.

### PDF files from standard input

The PDF language, unlike the PostScript language, inherently requires random access to the file. If you provide PDF to standard input using the special filename '`-`', Ghostscript will copy it to a temporary file before interpreting the PDF.

## Using Ghostscript with EPS files

Encapsulated PostScript (EPS) files are intended to be incorporated in other PostScript documents and may not display or print on their own. An EPS file must conform to the Document Structuring Conventions, must include a `%%BoundingBox` line to indicate the rectangle in which it will draw, must not use PostScript commands which will interfere with the document importing the EPS, and can have either zero pages or one page. Ghostscript has support for handling EPS files, but requires that the `%%BoundingBox` be in the header, not the trailer. To customize EPS handling, see EPS parameters.

For the official description of the EPS file format, please refer to the Adobe documentation in their tech note #5002. It is available from: http://partners.adobe.com/public/developer/ps/index_specs.html

## Using Ghostscript with overprinting and spot colors

In general with PostScript and PDF interpreters, the handling of overprinting and spot colors depends upon the process color model of the output device. Devices that produce gray or RGB output have an additive process color model. Devices which produce CMYK output have a subtractive process color model. Devices may, or may not, have support for spot colors.

> Note: The differences in appearance of files with overprinting and spot colors caused by the differences in the color model of the output device are part of the PostScript and PDF specifications. They are not due to a limitation in the implementation of Ghostscript or its output devices.

With devices which use a subtractive process color model, both PostScript and PDF allow the drawing of objects using colorants (inks) for one or more planes without affecting the data for the remaining colorants. Thus the inks for one object may `overprint` the inks for another object. In some cases this produces a transparency like effect. (The effects of overprinting should not be confused with the PDF 1.4 blending operations which are supported for all output devices.) Overprinting is not allowed for devices with an additive process color model. With files that use overprinting, the appearance of the resulting image can differ between devices which produce RGB output versus devices which produce CMYK output. Ghostscript automatically overprints (if needed) when the output device uses a subtractive process color model. For example, if the file is using overprinting, differences can be seen in the appearance of the output from the tiff24nc and tiff32nc devices which use an RGB and a CMYK process color models.

Most of the Ghostscript output devices do not have file formats which support spot colors. Instead spot colors are converted using the tint transform function contained within the color space definition.. However there are several devices which have support for spot colors. The PSD format (Adobe Photoshop) produced by the psdcmyk device contains both the raster data plus an equivalent CMYK color for each spot color. This allows Photoshop to simulate the appearance of the spot colors. The display device (MS Windows, OS/2, gtk+) can be used with different color models: Gray, RGB, CMYK only, or CMYK plus spot colors (separation). The display device, when using its CMYK plus spot color (separation) mode, also uses an equivalent CMYK color to simulate the appearance of the spot color. The tiffsep device creates output files for each separation (CMYK and any spot colors present). It also creates a composite CMYK file using an equivalent CMYK color to simulate the appearance of spot colors. The xcfcmyk device creates output files with spot colors placed in separate alpha channels. (The XCF file format does not currently directly support spot colors.)

Overprinting with spot colors is not allowed if the tint transform function is being used to convert spot colors. Thus if spot colors are used with overprinting, then the appearance of the result can differ between output devices. One result would be obtained with a CMYK only device and another would be obtained with a CMYK plus spot color device. In a worst case situation where a file has overprinting with both process (CMYK) and spot colors, it is possible to get three different appearances for the same input file using the tiff24nc (RGB), tiff32nc (CMYK), and tiffsep (CMYK plus spot colors) devices.

> In Adobe Acrobat, viewing of the effects of overprinting is enabled by the 'Overprint Preview' item in the 'Advanced' menu. This feature is not available in the free Acrobat Reader. The free Acrobat Reader also uses the tint transform functions to convert spot colors to the appropriate alternate color space.

## How Ghostscript finds files

When looking for initialization files (`gs_*.ps`, `pdf_*.ps`), font files, the `Fontmap` file, files named on the command line, and resource files, Ghostscript first tests whether the file name specifies an absolute path.

> Testing a file name for an absolute path
> System |  | Does the name ...
> Unix |  | Begin with `/` ?
> MS Windows |  | Have `:` as its second character, or begin with `/`, `\`, or `//servername/share/` ?
> VMS |  | Contain a node, device, or root specification?

If the test succeeds, Ghostscript tries to open the file using the name given. Otherwise it tries directories in this order:

1. The current directory (unless disabled by the `-P-` switch);
2. The directories specified by `-I` switches in the command line, if any;
3. The directories specified by the `GS_LIB` environment variable, if any;
4. The directories specified by the `GS_LIB_DEFAULT` macro (if any) in the makefile when this executable was built.

`GS_LIB_DEFAULT`, `GS_LIB`, and the `-I` parameter may specify either a single directory or a list of directories separated by a character appropriate for the operating system ("`:`" on Unix systems, "`,`" on VMS systems, and "`;`" on MS Windows systems). We think that trying the current directory first is a very bad idea -- it opens serious security loopholes and can lead to very confusing errors if one has more than one version of Ghostscript in one's environment -- but when we attempted to change it, users insisted that we change it back. You can disable looking in the current directory first by using the `-P-` switch.

Note that Ghostscript does not use this file searching algorithm for the `run` or `file` operators: for these operators, it simply opens the file with the name given. To run a file using the searching algorithm, use `runlibfile` instead of `run`.

### Finding PostScript Level 2 resources

Adobe specifies that resources are installed in a single directory. Ghostscript instead maintains a list of resource directories, and uses an extended method for finding resource files.

The search for a resource file depends on whether the value of the system parameter `GenericResourceDir` specifies an absolute path. The user may set it as explained in Resource-related parameters.

If the user doesn't set the system parameter `GenericResourceDir`, Ghostscript creates a default value for it with attaching the string `../Resource` to directory paths explained in How Ghostscript finds files, except the current directory. The first successful combination is used.

If the value of the system parameter `GenericResourceDir` is an absolute path (the default), Ghostscript assumes a single resource directory. It concatenates :

1. The value of the system parameter `GenericResourceDir`;
2. The name of the resource category (for instance, `CMap`);
3. The name of the resource instance (for instance, `Identity-H`).

If the value of the system parameter `GenericResourceDir` is not an absolute path, Ghostscript assumes multiple resource directories. In this case it concatenates :

1. A directory listed in the section How Ghostscript finds files, except the current directory;
2. The value of the system parameter `GenericResourceDir`;
3. The name of the resource category (for instance, `CMap`);
4. The name of the resource instance (for instance, `Identity-H`)

Due to possible variety of the part 1, the first successful combination is used. For example, if the value of the system parameter `GenericResourceDir` is the string `../Resource/` (or its equivalent in the file path syntax of the underlying platform), Ghostscript searches for `../Resource/CMap/Identity-H` from all directories listed in How Ghostscript finds files. So in this example, if the user on a Windows platform specifies the command line option `-I.;../gs/lib;c:/gs8.50/lib`, Ghostscript searches for `../gs/Resource/CMap/Identity-H` and then for `c:/gs8.50/Resource/CMap/Identity-H`.

To get a proper platform dependent syntax Ghostscript inserts the value of the system parameter `GenericResourcePathSep` (initially "`/`" on Unix and Windows, "`:`" on MacOS, "`.`" or "`]`" on OpenVMS). The string `../Resource` is replaced with a platform dependent equivalent.

In the case of multiple resource directories, the default `ResourceFileName` procedure retrieves either a path to the first avaliable resource, or if the resource is not available it returns a path starting with `GenericResourceDir`. Consequently Postscript installers of Postscript resources will overwrite an existing resource or add a new one to the first resource directory.

To look up fonts, after exhausting the search method described in the next section, it concatenates together

1. the value of the system parameter `FontResourceDir` (initially `/Resource/Font/`)
2. the name of the resource font (for instance, `Times-Roman`)

Note that even although the system parameters are named "somethingDir", they are not just plain directory names: they have "`/`" on the end, so that they can be concatenated with the category name or font name.

### Font lookup

Ghostscript has a slightly different way to find the file containing a font with a given name. This rule uses not only the search path defined by `-I`, `GS_LIB`, and `GS_LIB_DEFAULT` as described above, but also the directory that is the value of the `FontResourceDir` system parameter, and an additional list of directories that is the value of the `GS_FONTPATH` environment variable (or the value provided with the `-sFONTPATH=` switch, if present).

At startup time, Ghostscript reads in the `Fontmap` files in every directory on the search path (or in the list provided with the `-sFONTMAP=` switch, if present): these files are catalogs of fonts and the files that contain them. (See the documentation of fonts for details.) Then, when Ghostscript needs to find a font that isn't already loaded into memory, it goes through a series of steps.

- First, it looks up the font name in the combined Fontmaps. If there is an entry for the desired font name, and the file named in the entry can be found in some directory on the general search path (defined by `-I`, `GS_LIB`, and `GS_LIB_DEFAULT`), and the file is loaded successfully, and loading it defines a font of the desired name, that is the end of the process.
- If this process fails at any step, Ghostscript looks for a file whose name is the concatenation of the value of the `FontResourceDir` system parameter and the font name, with no extension. If such a file exists, can be loaded, and defines a font of the desired name, that again is the end. The value of `FontResourceDir` is normally the string `/Resource/Font/`, but it can be changed with the `setsystemparams` operator: see the PostScript Language Reference Manual for details.
- If that fails, Ghostscript then looks for a file on the general search path whose name is the desired font name, with no extension. If such a file exists, can be loaded, and defines a font of the desired name, that again is the end.
- If that too fails, Ghostscript looks at the `GS_FONTPATH` environment variable (or the value provided with the `-sFONTPATH=` switch, if present), which is also a list of directories. It goes to the first directory on the list, looking for all files that appear to contain PostScript fonts; it then adds all those files and fonts to the combined Fontmaps, and starts over.
- If scanning the first FONTPATH directory doesn't produce a file that provides the desired font, it adds the next directory on the FONTPATH list, and so on until either the font is defined successfully or the list is exhausted.
- Finally, if all else fails, it will try to find a substitute for the font from among the standard 35 fonts.

CID fonts (e.g. Chinese, Japanese and Korean) are found using a different method.

> Differences between search path and font path
> Search path |  | Font path
> `-I` switch |  | `-sFONTPATH=` switch
> `GS_LIB` and `GS_LIB_DEFAULT` environment variables |  | `GS_FONTPATH` environment variable
> Consulted first |  | Consulted only if search path and `FontResourceDir` don't provide the file.
> Font-name-to-file-name mapping given in Fontmap files; aliases are possible, and there need not be any relation between the font name in the Fontmap and the `FontName` in the file. |  | Font-name-to-file-name mapping is implicit -- the `FontName` in the file is used. Aliases are not possible.
> Only fonts and files named in Fontmap are used. |  | Every Type 1 font file in each directory is available; if TrueType fonts are supported (the `ttfont.dev` feature was included when the executable was built), they are also available.

If you are using one of the following types of computer, you may wish to set the environment variable `GS_FONTPATH` to the value indicated so that Ghostscript will automatically acquire all the installed Type 1 (and, if supported, TrueType) fonts (but see below for notes on systems marked with "*"):

> Suggested `GS_FONTPATH` for different systems
> |  | System type |  | `GS_FONTPATH`
> |  | Digital Unix |  | `/usr/lib/X11/fonts/Type1Adobe`
> |  | Ultrix |  | `/usr/lib/DPS/outline/decwin`
> |  | HP-UX 9 |  | `/usr/lib/X11/fonts/type1.st/typefaces`
> |  | IBM AIX |  | `/usr/lpp/DPS/fonts/outlines /usr/lpp/X11/lib/X11/fonts/Type1 /usr/lpp/X11/lib/X11/fonts/Type1/DPS`
> |  | NeXT |  | `/NextLibrary/Fonts/outline`
> * |  | SGI IRIX |  | `/usr/lib/DPS/outline/base /usr/lib/X11/fonts/Type1`
> |  | SunOS 4.x (NeWSprint only) |  | `newsprint_2.5/SUNWsteNP/reloc/$BASEDIR/NeWSprint/ small_openwin/lib/fonts`
> ** |  | SunOS 4.x |  | `/usr/openwin/lib/X11/fonts/Type1/outline`
> ** |  | Solaris 2.x |  | `/usr/openwin/lib/X11/fonts/Type1/outline`
> |  | VMS |  | `SYS$COMMON:[SYSFONT.XDPS.OUTLINE]`

> * On SGI IRIX systems, you must use `Fontmap.SGI` in place of `Fontmap` or `Fontmap.GS`, because otherwise the entries in `Fontmap` will take precedence over the fonts in the FONTPATH directories.

> ** On Solaris systems simply setting `GS_FONTPATH` or using `-sFONTPATH=` may not work, because for some reason some versions of Ghostscript can't seem to find any of the Type1 fonts in `/usr/openwin/lib/X11/fonts/Type1/outline`. (It says: "15 files, 15 scanned, 0 new fonts". We think this problem has been fixed in Ghostscript version 6.0, but we aren't sure because we've never been able to reproduce it.) See `Fontmap.Sol` instead. Also, on Solaris 2.x it's probably not worth your while to add Sun's fonts to your font path and Fontmap. The fonts Sun distributes on Solaris 2.x in the directories

> > `/usr/openwin/lib/X11/fonts/Type1
> > /usr/openwin/lib/X11/fonts/Type1/outline`

> are already represented among the ones distributed as part of Ghostscript; and on some test files, Sun's fonts have been shown to cause incorrect displays with Ghostscript.

These paths may not be exactly right for your installation; if the indicated directory doesn't contain files whose names are familiar font names like Courier and Helvetica, you may wish to ask your system administrator where to find these fonts.

Adobe Acrobat comes with a set of fourteen Type 1 fonts, on Unix typically in a directory called ...`/Acrobat3/Fonts`. There is no particular reason to use these instead of the corresponding fonts in the Ghostscript distribution (which are of just as good quality), except to save about a megabyte of disk space, but the installation documentation explains how to do it on Unix.

### CID fonts

CID fonts are PostScript resources containing a large number of glyphs (e.g. glyphs for Far East languages, Chinese, Japanese and Korean). Please refer to the PostScript Language Reference, third edition, for details.

CID font resources are a different kind of PostScript resource from fonts. In particular, they cannot be used as regular fonts. CID font resources must first be combined with a CMap resource, which defines specific codes for glyphs, before it can be used as a font. This allows the reuse of a collection of glyphs with different encodings.

The simplest method to request a font composed of a CID font resource and a CMap resource in a PostScript document is

> `/CIDFont-CMap findfont`

where `CIDFont` is a name of any CID font resource, and `CMap` is a name of a CMap resource designed for the same character collection. The interpreter will compose the font automatically from the specified CID font and CMap resources. Another method is possible using the `composefont` operator.

CID fonts must be placed in the `/Resource/CIDFont/` directory. They are not found using Font lookup on the search path or font path.

### CID font substitution

Substitution of CID font resources is controlled by the Ghostscript configuration file `lib/cidfmap`, which defines a CID font resource map. The file forms a table of records, each of which should use one of two formats, explained below. Users may modify `lib/cidfmap` to configure Ghostscript for a specific need.

To substitute a CID font resource with another CID font resource, add a record like this :

> `/Substituted /Original ;`

where `Substituted` is a name of CID font resource being used by a document, and `Original` is a name of an available CID font resource. Please pay attention that both them must be designed for same character collection. In other words, you cannot substitute a Japanese CID font resource with a Korean CID font resource, etc. CMap resource names must not appear in `lib/cidfmap`. The trailing semicolon and the space before it are both required.

To substitute (emulate) a CID font resource with a TrueType font file, add a record like this :

> `/Substituted << keys&values >> ;`

Where `keys&values` are explained in the table below.

Key | Type | Description
--- | --- | ---
`/Path` | string | A path to a TrueType font file. This must be an absolute path. If using `-dSAFER`, the directory containing the font file must be on one of the permitted paths.
`/FileType` | name | Must be `/TrueType`.
`/SubfontID` | integer | (optional) Index of the font in font collection, such as TTC. This is ignored if `Path` doesn't specify a collection. The first font in a collection is 0. Default value is 0.
`/CSI` | array of 2 elements | (required) Information for building `CIDSystemInfo`. The first element is a string, which specifies `Ordering`. The second element is a number, which specifies `Supplement`.

Currently only CIDFontType 2 can be emulated with a TrueType font. The TrueType font must contain enough characters to cover an Adobe character collection, which is specified in `Ordering` and used in documents.

Examples :

> `/Ryumin-Medium /ShinGo-Bold ;
> /MS-Mincho << /FileType /TrueType /Path (C:/WINDOWS/fonts/msmincho.ttc) /SubfontID 0 /CSI [(Japan1) 3] >> ;
> /Ryumin-Light /MS-Mincho ;
> /Batang << /FileType /TrueType /Path (C:/WINDOWS/fonts/batang.ttc) /SubfontID 0 /CSI [(Korea1) 3] >> ;
> /Gulim << /FileType /TrueType /Path (C:/WINDOWS/fonts/gulim.ttc) /SubfontID 0 /CSI [(Korea1) 3] >> ;
> /Dotum << /FileType /TrueType /Path (C:/WINDOWS/fonts/gulim.ttc) /SubfontID 2 /CSI [(Korea1) 3] >> ;
> /HYSMyeongJo-Medium /Batang ;
> /HYRGoThic-Medium /Gulim ;
> /HYGoThic-Medium /Dotum ;
> /SimSun << /FileType /TrueType /Path (C:/WINDOWS/fonts/simsun.ttc) /SubfontID 0 /CSI [(GB1) 2] >> ;
> /SimHei << /FileType /TrueType /Path (C:/WINDOWS/fonts/simhei.ttf) /SubfontID 0 /CSI [(GB1) 2] >> ;
> /STSong-Light /SimSun ;
> /STHeiti-Regular /SimHei ;
> `

Note that the font file path uses Postscript syntax for strings. Due to that backslashes must be represented as a double backslash each.

Note that loading truetype fonts directly from >`/Resources/CIDFont` is no longer supported. There is no reliable way to generate a character ordering for truetype fonts. The 7.0x versions of Ghostscript supported this by assuming a Japanese character ordering. This is replaced in the 8.0x and later releases with the more general `cidfmap` mechanism.

The PDF specification requires CID font files to be embedded, however some documents omit them. As a workaround the PDF interpreter applies an additional substitution method when a requested CID font resource is not embedded and it is not available. It takes values of the keys `Registry` and `Ordering` from the `CIDFontSystem` dictionary, and concatenates them with a dash inserted. For example, if a PDF CID font resource specifies

> `/CIDSystemInfo << /Registry (Adobe) /Ordering (CNS1) /Supplement 1 >>`

the generated subsitituite name is `Adobe-CNS1`. The latter may look some confusing for a font name, but we keep it for compatibility with older Ghostscript versions, which do so due to a historical reason. Add a proper record to `lib/cidfmap` to provide it.

Please note that when a PDF font resource specifies

> `/Registry (Adobe) /Ordering (Identity)`

there is no way to determine the language properly. If the CID font file is not embedded, the `Adobe-Identity` record depends on the document and a correct record isn't possible when a document refers to multiple Far East languages. In the latter case add individual records for specific CID font names used in the document.

Consequently, if you want to handle any PDF document with non-embedded CID fonts (which isn't a correct PDF), you need to create a suitable `lib/cidfmap` by hand, possibly a specific one for each document.

### Temporary files

> Where Ghostscript puts temporary files
> Platform |  | Filename |  | Location
> MS Windows and OpenVMS |  | `_temp_`XX.XXX |  | Current directory
> OS/2 |  | `gs`XXXXXX |  | Current directory
> Unix |  | `gs_`XXXXX |  | `/tmp`

You can change in which directory Ghostscript creates temporary files by setting the `TMPDIR` or `TEMP` environment variable to the name of the directory you want used. Ghostscript currently doesn't do a very good job of deleting temporary files if it exits because of an error; you may have to delete them manually from time to time.

## Notes on specific platforms

### Unix

The Ghostscript distribution includes some Unix shell scripts to use with Ghostscript in different environments. These are all user-contributed code, so if you have questions, please contact the user identified in the file, not Aladdin Enterprises or artofcode LLC.

`pv.sh`
  Preview a specified page of a `dvi` file in an X window

`sysvlp.sh`
  System V 3.2 lp interface for parallel printer

`pj-gs.sh`
  Printing on an H-P PaintJet under HP-UX

`unix-lpr.sh`
  Queue filter for `lpr` under Unix; its documentation is intended for system administrators

`lprsetup.sh`
  Setup for `unix-lpr.sh`

### VMS

- To be able to specify switches and file names when invoking the interpreter, define `gs` as a foreign command:

  > `$ gs == "$`disk`:[`directory`]gs.exe`"

  where the "disk" and "directory" specify where the Ghostscript executable is located. For instance,

  > `$ gs == "$dua1:[ghostscript]gs.exe"`

- On VMS systems, the last character of each "directory" name indicates what sort of entity the "directory" refers to. If the "directory" name ends with a colon "`:`", it is taken to refer to a logical device, for instance

  > `$ define ghostscript_device dua1:[ghostscript_510]
  > $ define gs_lib ghostscript_device:`

  If the "directory" name ends with a closing square bracket "`]`", it is taken to refer to a real directory, for instance

  > `$ define gs_lib dua1:[ghostscript]`

- Defining the logical `GS_LIB`

  > `$ define gs_lib` disk`:[`directory`]`

  allows Ghostscript to find its initialization files in the Ghostscript directory even if that's not where the executable resides.

- Although VMS DCL itself converts unquoted parameters to upper case, C programs such as Ghostscript receive their parameters through the C runtime library, which forces all unquoted command-line parameters to lower case. That is, with the command

  > `$ gs -Isys$login:`

  Ghostscript sees the switch as `-isys$login`, which doesn't work. To preserve the case of switches, quote them like this:

  > `$ gs "-Isys$login:"`

- If you write printer output to a file with `-sOutputFile=` and then want to print the file later, use "`PRINT/PASSALL`".

- PDF files (or PostScript files that use the `setfileposition` operator) must be "stream LF" type files to work properly on VMS systems. (Note: This definitely matters if Ghostscript was compiled with DEC C; we are not sure of the situation if you use `gcc`.) Because of this, if you transfer files by FTP, you probably need to do one of these two things after the transfer:
  1. If the FTP transfer was in text (ASCII) mode:

     > `$ convert/fdl=streamlf.fdl` input-file output-file

     where the contents of the file `STREAMLF.FDL` are

     >     FILE
     >             ORGANIZATION            sequential

     >     RECORD
     >             BLOCK_SPAN              yes
     >             CARRIAGE_CONTROL        carriage_return
     >             FORMAT                  stream_lf

  2. If the FTP transfer was in binary mode:

     > `$ set file/attribute=(rfm:stmlf)`

#### Using X Windows on VMS

If you are using on an X Windows display, you can set it up with the node name and network transport, for instance

> `$ set display/create/node="doof.city.com"/transport=tcpip`

and then run Ghostscript by typing `gs` at the command line.

### MS Windows

The name of the Ghostscript command line executable on MS Windows is `gswin32c` so use this instead of the plain '`gs`' in the quickstart examples.

You must add gs\`bin` and gs\`lib` to the `PATH`, where gs is the top-level Ghostscript directory.

When passing options to ghostcript through a batch file wrapper such as `ps2pdf.bat` you need to substitute '#' for '=' as the separator between options and their arguments. For example:

>     ps2pdf -sPAPERSIZE#a4 file.ps file.pdf

Ghostscript treats '#' the same internally, and the '=' is mangled by the command shell.

There is also an older version for windows called just `gswin32` that provides its own window for the interactive postscript prompt. Except on Windows 3.1, gswin32c is the better option since it uses the native command prompt window.

### MS-DOS

Note: Ghostscript is no longer supported on MS-DOS.

Invoking Ghostscript from the command prompt in Windows is supported by the Windows executable described above.

### X Windows

Ghostscript looks for the following resources under the program name `ghostscript` and class name `Ghostscript`; the ones marked "**" are calculated from display metrics:

> X Windows resources
> Name |  | Class |  | Default
> `background` |  | `Background` |  | `white`
> `foreground` |  | `Foreground` |  | `black`
> `borderColor` |  | `BorderColor` |  | `black`
> `borderWidth` |  | `BorderWidth` |  | `1`
> `geometry` |  | `Geometry` |  | `NULL`
> `xResolution` |  | `Resolution` |  | **
> `yResolution` |  | `Resolution` |  | **
> `useExternalFonts` |  | `UseExternalFonts` |  | `true`
> `useScalableFonts` |  | `UseScalableFonts` |  | `true`
> `logExternalFonts` |  | `LogExternalFonts` |  | `false`
> `externalFontTolerance` |  | `ExternalFontTolerance` |  | `10.0`
> `palette` |  | `Palette` |  | `Color`
> `maxGrayRamp` |  | `MaxGrayRamp` |  | `128`
> `maxRGBRamp` |  | `MaxRGBRamp` |  | `5`
> `maxDynamicColors` |  | `MaxDynamicColors` |  | `256`
> `useBackingPixmap` |  | `UseBackingPixmap` |  | `true`
> `useXPutImage` |  | `UseXPutImage` |  | `true`
> `useXSetTile` |  | `UseXSetTile` |  | `true`
> `regularFonts` |  | `RegularFonts` |  | See "X fonts"
> `symbolFonts` |  | `SymbolFonts` |  | See "X fonts"
> `dingbatFonts` |  | `DingbatFonts` |  | See "X fonts"

#### X resources

- To set X resources, put them in a file (such as `~/.Xdefaults` on Unix) in a form like this:

  > `Ghostscript*geometry:` | `` | `595x842-0+0`
  > `Ghostscript*xResolution:` | `` | `72`
  > `Ghostscript*yResolution:` | `` | `72`

  Then merge these resources into the X server's resource database:

  > `xrdb -merge ~/.Xdefaults`

- Ghostscript doesn't look at the default system background and foreground colors; if you want to change the background or foreground color, you must set them explicitly for Ghostscript. This is a deliberate choice, so that PostScript documents will display correctly by default -- with white as white and black as black -- even if text windows use other colors.
- The `geometry` resource affects only window placement.
- Resolution is expressed in pixels per inch (1 inch = 25.4mm).
- The font tolerance gives the largest acceptable difference in height of the screen font, expressed as a percentage of the height of the desired font.
- The `palette` resource can be used to restrict Ghostscript to using a grayscale or monochrome palette.
- `maxRGBRamp` and `maxGrayRamp` control the maximum number of colors that ghostscript allocates ahead of time for the dither cube (ramp). Ghostscript never preallocates more than half the cells in a colormap. `maxDynamicColors` controls the maximum number of colors that Ghostscript will allocate dynamically in the colormap.

#### Working around bugs in X servers

The "`use`..." resources exist primarily to work around bugs in X servers.

- Old versions of DEC's X server (DECwindows) have bugs that require setting `useXPutImage` or `useXSetTile` to `false`.
- Some servers do not implement backing pixmaps properly, or do not have enough memory for them. If you get strange behavior or "out of memory" messages, try setting `useBackingPixmap` to `false`.
- Some servers do not implement tiling properly. This appears as broad bands of color where dither patterns should appear. If this happens, try setting `useXSetTile` to `false`.
- Some servers do not implement bitmap or pixmap displaying properly. This may appear as white or black rectangles where characters should appear; or characters may appear in "inverse video" (for instance, white on a black rectangle rather than black on white). If this happens, try setting `useXPutImage` to `false`.

#### X fonts

To use native X11 fonts, Ghostscript must map PostScript font names to the XLFD font names. The resources `regularFonts` (fonts available in standard or ISO-Latin-1 encoding), `symbolFonts` (using Symbol encoding), and `dingbatFonts` (using Dingbat encoding) give the name mapping for different encodings. The XLFD font name in the mapping must contain 7 dashes; the X driver adds the additional size and encoding fields to bring the total number of dashes in the font name to 14. See the appendix "X default font mappings" for the full list of default mappings.

Users who switch regularly between different X servers may wish to use the "*" wild card in place of the foundry name (`itc`, `monotype`, `linotype`, `b&h`, or `adobe`); users who do not switch X servers should leave the explicit foundry in the name, since it speeds up access to fonts.

Ghostscript takes advantage of the "HP XLFD Enhancements," if available, to use native X11 fonts for fonts that are anamorphically scaled, rotated, or mirrored. If the changes have been installed to the X or font server, they are automatically used when appropriate.

#### Using Ghostscript fonts on X displays

Font files distributed with Ghostscript can be used on X Windows displays. You can find full instructions in the documentation on fonts.

#### X device parameters

In addition to the device parameters recognized by all devices, Ghostscript's X driver provides parameters to adjust its performance. Users will rarely need to modify these. Note that these are parameters to be set with the `-d` switch in the command line (e.g., `-dMaxBitmap=10000000`), not resources to be defined in the `~/.Xdefaults` file.

`AlwaysUpdate <boolean>`
  If `true`, the driver updates the screen after each primitive drawing operation; if `false` (the default), the driver uses an intelligent buffered updating algorithm.

`MaxBitmap <integer>`
  If the amount of memory required to hold the pixmap for the window is no more than the value of `MaxBitmap`, the driver will draw to a pixmap in Ghostscript's address space (called a "client-side pixmap") and will copy it to the screen from time to time; if the amount of memory required for the pixmap exceeds the value of `MaxBitmap`, the driver will draw to a server pixmap. Using a client-side pixmap usually provides better performance -- for bitmap images, possibly much better performance -- but since it may require quite a lot of RAM (e.g., about 2.2 Mb for a 24-bit 1024x768 window), the default value of `MaxBitmap` is 0.

`MaxTempPixmap, MaxTempImage, MaxBufferedTotal, MaxBufferedArea, MaxBufferedCount <integer>`
  These control various aspects of the driver's buffering behavior. For details, please consult the source file `gdevx.h`.

### SCO Unix

Because of bugs in the SCO Unix kernel, Ghostscript will not work if you select direct screen output and also allow it to write messages on the console. If you are using direct screen output, redirect Ghostscript's terminal output to a file.

## Command line options

Unless otherwise noted, these switches can be used on all platforms.

### General switches

#### Input control

`@`filename
  Causes Ghostscript to read filename and treat its contents the same as the command line. (This was intended primarily for getting around DOS's 128-character limit on the length of a command line.) Switches or file names in the file may be separated by any amount of white space (space, tab, line break); there is no limit on the size of the file.

`--` filename arg1 ...
`-+` filename arg1 ...
  Takes the next argument as a file name as usual, but takes all remaining arguments (even if they have the syntactic form of switches) and defines the name `ARGUMENTS` in userdict (not systemdict) as an array of those strings, before running the file. When Ghostscript finishes executing the file, it exits back to the shell.

`-@` filename arg1 ...
  Does the same thing as `--` and `-+`, but expands `@`filename arguments.

`-`
`-_`
  These are not really switches: they tell Ghostscript to read from standard input, which is coming from a file or a pipe, with or without buffering. On some systems, Ghostscript may read the input one character at a time, which is useful for programs such as ghostview that generate input for Ghostscript dynamically and watch for some response, but can slow processing. If performance is significantly slower than with a named file, try '`-_`' which always reads the input in blocks. However, '`-`' is equivalent on most systems.

`-c` token ...
`-c` string ...
  Interprets arguments as PostScript code up to the next argument that begins with "`-`" followed by a non-digit, or with "`@`". For example, if the file `quit.ps` contains just the word "`quit`", then `-c quit` on the command line is equivalent to `quit.ps` there. Each argument must be valid PostScript, either individual tokens as defined by the `token` operator, or a string containing valid PostScript.

`-f`
  Interprets following non-switch arguments as file names to be executed using the normal `run` command. Since this is the default behavior, `-f` is useful only for terminating the list of tokens for the `-c` switch.

`-f` filename
  Execute the given file, even if its name begins with a "`-`" or "`@`".

#### File searching

Note that by "library files" here we mean all the files identified using the search rule under "How Ghostscript finds files" above: Ghostscript's own initialization files, fonts, and files named on the command line.

`-I` directories
  Adds the designated list of directories at the head of the search path for library files.

`-P`
  Makes Ghostscript look first in the current directory for library files. This is currently the default.

`-P-`
  Makes Ghostscript not look first in the current directory for library files (unless, of course, the first explicitly supplied directory is "`.`").

#### Setting parameters

`-D` name
`-d` name
  Define a name in systemdict with value=true.

`-D` name`=`token
`-d` name`=`token
  Define a name in systemdict with the given value. The value must be a valid PostScript token (as defined by the `token` operator). If the token is a non-literal name, it must be true, false, or null. It is recommeded that this is used only for simple values -- use `-c` (above) for complex values such as procedures, arrays or dictionaries.
  Note that these values are defined before other names in systemdict, so any name that that conflicts with one usually in systemdict will be replaced by the normal definition during the interpreter initialization.

`-S` name`=`string
`-s` name`=`string
  Define a name in systemdict with a given string as value. This is different from `-d`. For example, `-dXYZ=35` on the command line is equivalent to the program fragment

  > `/XYZ 35 def`

  whereas `-sXYZ=35` is equivalent to

  > `/XYZ (35) def`

`-u` name
  Un-define a name, cancelling `-d` or `-s`.

Note that the initialization file `gs_init.ps` makes `systemdict` read-only, so the values of names defined with `-D`, `-d`, `-S`, and `-s` cannot be changed -- although, of course, they can be superseded by definitions in `userdict` or other dictionaries. However, device parameters set this way (`PageSize`, `Margins`, etc.) are not read-only, and can be changed by code in PostScript files.

`-g` number1 `x` number2
  Equivalent to `-dDEVICEWIDTH=`number1 and `-dDEVICEHEIGHT=`number2, specifying the device width and height in pixels for the benefit of devices such as X11 windows and VESA displays that require (or allow) you to specify width and height. Note that this causes documents of other sizes to be clipped, not scaled: see `-dFIXEDMEDIA` below.

`-r` number (same as `-r` number `x` number)
`-r` number1 `x` number2
  Equivalent to `-dDEVICEXRESOLUTION=`number1 and `-dDEVICEYRESOLUTION=`number2, specifying the device horizontal and vertical resolution in pixels per inch for the benefit of devices such as printers that support multiple X and Y resolutions.

#### Suppress messages

`-q`
  Quiet startup: suppress normal startup messages, and also do the equivalent of `-dQUIET`.

### Parameter switches (`-d` and `-s`)

As noted above, `-d` and `-s` define initial values for PostScript names. Some of these names are parameters that control the interpreter or the graphics engine. You can also use `-d` or `-s` to define a value for any device parameter of the initial device (the one defined with `-sDEVICE=`, or the default device if this switch is not used). For example, since the `ppmraw` device has a numeric `GrayValues` parameter that controls the number of bits per component, `-sDEVICE=ppmraw -dGrayValues=16` will make this the default device and set the number of bits per component to 4 (log2(16)).

#### Rendering parameters

`-dCOLORSCREEN
-dCOLORSCREEN=0
-dCOLORSCREEN=false`
  On high-resolution devices (at least 150 dpi resolution, or `-dDITHERPPI` specified), `-dCOLORSCREEN` forces the use of separate halftone screens with different angles for CMYK or RGB if halftones are needed (this produces the best-quality output); `-dCOLORSCREEN=0` uses separate screens with the same frequency and angle; `-dCOLORSCREEN=false` forces the use of a single binary screen. The default if `COLORSCREEN` is not specified is to use separate screens with different angles if the device has fewer than 5 bits per color, and a single binary screen (which is never actually used under normal circumstances) on all other devices.

`-dDITHERPPI=`lpi
  Forces all devices to be considered high-resolution, and forces use of a halftone screen or screens with lpi lines per inch, disregarding the actual device resolution. Reasonable values for lpi are N/5 to N/20, where N is the resolution in dots per inch.

`-dDOINTERPOLATE`
  Turns on image interpolation for all images, improving image quality for scaled images at the expense of speed. Note that `-dNOINTERPOLATE` overrides `-dDOINTERPOLATE` if both are specified.

`-dTextAlphaBits=`n
`-dGraphicsAlphaBits=`n
  These options control the use of subsample antialiasing. Their use is highly recommended for producing high quality rasterizations. The subsampling box size n should be 4 for optimum output, but smaller values can be used for faster rendering. Antialiasing is enabled separately for text and graphics content. Allowed values are 1, 2 or 4.

  Note that because of the way antialiasing blends the edges of shapes into the background when they are drawn some files that rely on joining separate filled polygons together to cover an area may not render as expected with `GraphicsAlphaBits` at 2 or 4. If you encounter strange lines within solid areas, try rendering that file again with `-dGraphicsAlphaBits=1`.

`-dAlignToPixels=`n
  Chooses glyph alignent to integral pixel boundaries (if set to the value 1) or to subpixels (value 0). Subpixels are a smaller raster grid which is used internally for text antialiasing. The number of subpixels in a pixel usually is `2^TextAlphaBits`, but this may be automatically reduced for big characters to save space in character cache.

  The parameter has no effect if `-dTextAlphaBits=1`. Default value is 0.

  Setting `-dAlignToPixels=0` can improve rendering of poorly hinted fonts, but may impair the appearance of well-hinted fonts.

`-dGridFitTT=`n
  This specifies the initial value for the implementation specific user parameter GridFitTT. It controls grid fitting of True Type fonts (Sometimes referred to as "hinting", but strictly speaking the latter is a feature of Type 1 fonts). Setting this to 2 enables automatic grid fitting for True Type glyphs. The value 0 disables grid fitting. The default value is 2. For more information see the description of the user parameter GridFitTT.

`-dUseCIEColor`
  Set UseCIEColor in the page device dictionary, remapping device-dependent color values through a CIE color space. This can can improve conversion of CMYK documents to RGB.

`-dNOCIE`
  Substitutes `DeviceGray` and `DeviceRGB` for CIEBasedA and CIEBasedABC color spaces respectively. Useful only on very slow systems where color accuracy is less important.

`-dNOSUBSTDEVICECOLORS`
  This switch prevents the substitution of the `ColorSpace` resources (`DefaultGray`, `DefaultRGB`, and `DefaultCMYK`) for the `DeviceGray`, `DeviceRGB`, and `DeviceCMYK` color spaces. This switch is primarily useful for PDF creation using the `pdfwrite` device when retaining the color spaces from the original document is important.

`-dNOPSICC`
  Disables the automatic loading and use of an input color space that is contained in a PostScript file as DSC comments starting with the %%BeginICCProfile: comment. ICC profiles are sometimes embedded by applications to convey the exact input color space allowing better color fidelity. Since the embedded ICC profiles often use multidimensional RenderTables, color conversion may be slower than using the Default color conversion invoked when the `-dUseCIEColor` option is specified, therefore the `-dNOPSICC` option may result in improved performance at slightly reduced color fidelity.

`-dNOINTERPOLATE`
  Turns off image interpolation, improving performance on interpolated images at the expense of image quality. `-dNOINTERPOLATE` overrides `-dDOINTERPOLATE`.

`-dNOTRANSPARENCY`
  Turns off PDF 1.4 transparency, resulting in faster (but possibly incorrect) rendering of pages containing PDF 1.4 transparency and blending.

`-dNO_TN5044`
  Turns off the TN 5044 psuedo operators. These psuedo operators are not a part of the official Postscript specification. However they are defined in Technical Note #5044 Color Separation Conventions for PostScript Language Programs. These psuedo operators are required for some files from QuarkXPress. However some files from Corel 9 and Illustrator 88 do not operate properly if these operators are present.

`-dDOPS`
  Enables processing of DoPS directives in PDF files. DoPS has in fact been deprecated for some time. Use of this option is not recommended in security-conscious applications, as it increases the scope for malicious code. `-dDOPS` has no effect on processing of PostScript source files. Note: in releases 7.30 and earlier, processing of DoPS was always enabled.

#### Page parameters

`-dFIXEDMEDIA`
  Causes the media size to be fixed after initialization, forcing pages of other sizes or orientations to be clipped. This may be useful when printing documents on a printer that can handle their requested paper size but whose default is some other size. Note that `-g` automatically sets `-dFIXEDMEDIA`, but `-sPAPERSIZE=` does not.

`-dFIXEDRESOLUTION`
  Causes the media resolution to be fixed similarly. `-r` automatically sets `-dFIXEDRESOLUTION`.

`-dORIENT1=true
-dORIENT1=false`
  Defines the meaning of the 0 and 1 orientation values for the setpage[params] compatibility operators. The default value of `ORIENT1` is true (set in `gs_init.ps`), which is the correct value for most files that use setpage[params] at all, namely, files produced by badly designed applications that "know" that the output will be printed on certain roll-media printers: these applications use 0 to mean landscape and 1 to mean portrait. `-dORIENT1=false` declares that 0 means portrait and 1 means landscape, which is the convention used by a smaller number of files produced by properly written applications.

`-dDEVICEWIDTHPOINTS=`w
`-dDEVICEHEIGHTPOINTS=`h
  Sets the initial page width to w or initial page height to h respectively, specified in 1/72" units.

`-sDEFAULTPAPERSIZE=`a4
  This value will be used to replace the device default papersize ONLY if the default papersize for the device is 'letter' or 'a4' serving to insulate users of A4 or 8.5x11 from particular device defaults (the collection of contributed drivers in Ghostscript vary as to the default size).

#### Font-related parameters

`-dDISKFONTS`
  Causes individual character outlines to be loaded from the disk the first time they are encountered. (Normally Ghostscript loads all the character outlines when it loads a font.) This may allow loading more fonts into memory at the expense of slower rendering. `DISKFONTS` is effective only if the diskfont feature was built into the executable; otherwise it is ignored.

`-dLOCALFONTS`
  Causes Type 1 fonts to be loaded into the current VM -- normally local VM -- instead of always being loaded into global VM. Useful only for compatibility with Adobe printers for loading some obsolete fonts.

`-dNOCCFONTS`
  Suppresses the use of fonts precompiled into the Ghostscript executable. See "Precompiling fonts" in the documentation on fonts for details. This is probably useful only for debugging.

`-dNOFONTMAP`
  Suppresses the normal loading of the Fontmap file. This may be useful in environments without a file system.

`-dNOFONTPATH`
  Suppresses consultation of `GS_FONTPATH`. This may be useful for debugging.

`-dNOPLATFONTS`
  Disables the use of fonts supplied by the underlying platform (X Windows or Microsoft Windows). This may be needed if the platform fonts look undesirably different from the scalable fonts.

`-sFONTMAP=`filename1`;`filename2`;`...
  Specifies alternate name or names for the Fontmap file. Note that the names are separated by "`:`" on Unix systems, by "`;`" on MS Windows systems, and by "`,`" on VMS systems, just as for search paths.

`-sFONTPATH=`dir1`;`dir2`;`...
  Specifies a list of directories that will be scanned when looking for fonts not found on the search path, overriding the environment variable `GS_FONTPATH`.

`-sSUBSTFONT=`fontname
  Causes the given font to be substituted for all unknown fonts, instead of using the normal intelligent substitution algorithm. Also, in this case, the font returned by `findfont` is the actual font named fontname, not a copy of the font with its `FontName` changed to the requested one. THIS OPTION SHOULD NOT BE USED WITH HIGH LEVEL DEVICES, such as `pdfwrite`, because it prevents such devices from providing the original font names in the output document. The font specified (fontname) will be embedded instead, limiting all future users of the document to the same approximate rendering.

#### Resource-related parameters

`-sGenericResourceDir=path`
  Specifies a path to resource files. The value is platform dependent. It must end with a directory separator.

  Adobe specifies `GenericResourceDir` to be an absolute path to a single resource directory. Ghostscript instead maintains multiple resource directories and uses an extended method for finding resources, which is explained in "Finding PostScript Level 2 resources".

  Due to the extended search method, Ghostscript uses `GenericResourceDir` only as a default directory for resources being not installed. Therefore `GenericResourceDir` may be considered as a place where new resources to be installed. The default implementation of the function `ResourceFileName` uses `GenericResourceDir` when (1) it is an absolute path, or (2) the resource file is absent. The extended search method does not call `ResourceFileName` .

  Default value is `(./Resource/)` for Unix, and an equivalent one on other platforms.

`-sFontResourceDir=path`
  Specifies a path where font files are installed. It's meaning is similar to `GenericResourceDir`.

  Default value is `(./Font/)` for Unix, and an equivalent one on other platforms.

#### Interaction-related parameters

`-dBATCH`
  Causes Ghostscript to exit after processing all files named on the command line, rather than going into an interactive loop reading PostScript commands. Equivalent to putting -c quit at the end of the command line.

`-dNOPAGEPROMPT`
  Disables only the prompt, but not the pause, at the end of each page. This may be useful on PC displays that get confused if a program attempts to write text to the console while the display is in a graphics mode.

`-dNOPAUSE`
  Disables the prompt and pause at the end of each page. Normally one should use this (along with `-dBATCH`) when producing output on a printer or to a file; it also may be desirable for applications where another program is "driving" Ghostscript.

`-dNOPROMPT`
  Disables the prompt printed by Ghostscript when it expects interactive input, as well as the end-of-page prompt (`-dNOPAGEPROMPT`); also disables the implicit `flushpage` that normally occurs each time Ghostscript asks for more input. This allows piping input directly into Ghostscript, as long as the data doesn't refer to `currentfile`.

`-dQUIET`
  Suppresses routine information comments on standard output. This is currently necessary when redirecting device output to standard output.

`-dSHORTERRORS`
  Makes certain error and information messages more Adobe-compatible.

`-sstdout=`filename
  Redirect PostScript `%stdout` to a file or `stderr`, to avoid it being mixed with device stdout. To redirect stdout to stderr use `-sstdout=%stderr`. To cancel redirection of stdout use `-sstdout=%stdout` or `-sstdout=-`.

`-dTTYPAUSE`
  Causes Ghostscript to read a character from `/dev/tty`, rather than standard input, at the end of each page. This may be useful if input is coming from a pipe. Note that `-dTTYPAUSE` overrides `-dNOPAUSE`.

#### Device and output selection parameters

`-dNODISPLAY`
  Initializes Ghostscript with a null device (a device that discards the output image) rather than the default device or the device selected with `-sDEVICE=`. This is usually useful only when running PostScript code whose purpose is to compute something rather than to produce an output image; for instance, when converting PostScript to PDF.

`-sDEVICE=`device
  Selects an alternate initial output device.

`-sOutputFile=`filename
  Selects an alternate output file (or pipe) for the initial output device, as described above.

#### EPS parameters

`-dEPSCrop`
  Crop an EPS file to the bounding box. This is useful when converting an EPS file to a bitmap.

`-dEPSFitPage`
  Resize an EPS file to fit the page. This is useful for enlarging an EPS file to fit the paper size when printing.

`-dNOEPS`
  Prevent special processing of EPS files. This is useful when EPS files have incorrect Document Structuring Convention comments.

#### Other parameters

`-dDELAYBIND`
  Causes `bind` to remember all its invocations, but not actually execute them until the `.bindnow` procedure is called. Useful only for certain specialized packages like `pstotext` that redefine operators. See the documentation for `.bindnow` for more information on using this feature.

`-dDOPDFMARKS`
  Causes `pdfmark` to be called for bookmarks, annotations, links and cropbox when processing PDF files. Normally, `pdfmark` is only called for these types for PostScript files or when the output device requests it (e.g. pdfwrite device).

`-dJOBSERVER`
  Define `\004 (^D)` to start a new encapsulated job used for compatibility with Adobe PS Interpreters that ordinarily run under a job server. The `-dNOOUTERSAVE` switch is ignored if `-dJOBSERVER` is specified since job servers always execute the input PostScript under a save level, although the `exitserver` operator can be used to escape from the encapsulated job and execute as if the `-dNOOUTERSAVE` was specified.

  This also requires that the input be from stdin, otherwise an error will result (`Error: /invalidrestore in --restore--`).

  Example usage is:

          gs ... -dJOBSERVER - < inputfile.ps
                           -or-
          cat inputfile.ps | gs ... -dJOBSERVER -

  Note: The `^D` does not result in an end-of-file action on stdin as it may on some PostScript printers that rely on TBCP (Tagged Binary Communication Protocol) to cause an out-of-band `^D` to signal EOF in a stream input data. This means that direct file actions on stdin such as `flushfile` and `closefile` will affect processing of data beyond the `^D` in the stream.

`-dNOBIND`
  Disables the `bind` operator. Useful only for debugging.

`-dNOCACHE`
  Disables character caching. Useful only for debugging.

`-dNOGC`
  Suppresses the initial automatic enabling of the garbage collector in Level 2 systems. (The `vmreclaim` operator is not disabled.) Useful only for debugging.

`-dNOOUTERSAVE`
  Suppresses the initial save that is used for compatibility with Adobe PS Interpreters that ordinarily run under a job server. If a job server is going to be used to set up the outermost save level, then `-dNOOUTERSAVE` should be used so that the restore between jobs will restore global VM as expected.

`-dNOSAFER` (equivalent to `-dDELAYSAFER`).
  This flag disables SAFER mode until the `.setsafe` procedure is run. This is intended for clients or scripts that cannot operate in SAFER mode. If Ghostscript is started with `-dNOSAFER` or `-dDELAYSAFER`, PostScript programs are allowed to read, write, rename or delete any files in the system that are not protected by operating system permissions.

  This mode should be used with caution, and `.setsafe` should be run prior to running any PostScript file with unknown contents.

`-dSAFER`
  Disables the `deletefile` and `renamefile` operators, and the ability to open piped commands (`%pipe%`cmd) at all. Only `%stdout` and `%stderr` can be opened for writing. Disables reading of files other than `%stdin`, those given as a command line argument, or those contained on one of the paths given by LIBPATH and FONTPATH and specified by the system params /FontResourceDir and /GenericResourceDir.

  This mode also sets the .LockSafetyParams parameter of the default device, or the device specified with the `-sDEVICE=` switch to protect against programs that attempt to write to files using the OutputFile device parameter. Note that since the device parameters specified on the command line (including OutputFile) are set prior to SAFER mode, the `-sOutputFile=...` on the command line is unrestricted.

  SAFER mode also prevents changing the /GenericResourceDir, /FontResourceDir and either the /SystemParamsPassword or the /StartJobPassword.

  Note: While SAFER mode is not the default, in a subsequent release of Ghostscript, SAFER mode will be the default thus scripts or programs that need to open files or set restricted parameters will require the `-dNOSAFER` command line option.

  When running -dNOSAFER it is possible to perform a `save`, followed by `.setsafe`, execute a file or procedure in SAFER mode, then use `restore` to return to NOSAFER mode. In order to prevent the save object from being restored by the foreign file or procedure, the .runandhide operator should be used to hide the save object from the restricted procedure.

`-dSTRICT`
  Disables as many Ghostscript extensions as feasible, to be more helpful in debugging applications that produce output for Adobe and other RIPs.

`-dWRITESYSTEMDICT`
  Leaves `systemdict` writable. This is necessary when running special utility programs such as `font2c` and `pcharstr`, which must bypass normal PostScript access protection.

## Improving performance

Ghostscript attempts to find an optimum balance between speed and memory consumption, but there are some cases in which you may get a very large speedup by telling Ghostscript to use more memory.

- If you are using X Windows, setting the `-dMaxBitmap=` parameter described above may dramatically improve performance on files that have a lot of bitmap images.
- If you are using Chinese, Japanese, or other fonts with very large character sets, adding the following sequence of switches before the first file name may dramatically improve performance at the cost of an additional 2-3 Mb of memory: `-c 3000000 setvmthreshold -f`. This can also be useful in processing large documents when using a high-level output device (like pdfwrite) that maintains significant internal state. In fact, the `.setpdfwrite` operator used by the ps2pdf script and others sets a vmthreshold value of 3 MB to account for this.

## Summary of environment variables

`GS`, `GSC` (MS Windows only)
  Specify the names of the Ghostscript executables. `GS` brings up a new typein window and possibly a graphics window; `GSC` uses the DOS console. If these are not set, `GS` defaults to `gswin32`, and `GSC` defaults to `gswin32c`.

`GS_DEVICE`
  Defines the default output device. This overrides the compiled-in default, but is overridden by any commandline setting.

`GS_FONTPATH`
  Specifies a list of directories to scan for fonts if a font requested can't be found anywhere on the search path.

`GS_LIB`
  Provides a search path for initialization files and fonts.

`GS_OPTIONS`
  Defines a list of command-line arguments to be processed before the ones actually specified on the command line. For example, setting `GS_DEVICE` to XYZ is equivalent to setting `GS_OPTIONS` to `-sDEVICE=XYZ`. The contents of `GS_OPTIONS` are not limited to switches; they may include actual file names or even "@file" arguments.

`TEMP`, `TMPDIR`
  Defines a directory name for temporary files. If both `TEMP` and `TMPDIR` are defined, `TMPDIR` takes precedence.

## Debugging

The information here describing is probably interesting only to developers.

#### Debug switches

There are several debugging switches that are detected by the interpreter. These switches are available whether or not Ghostscript was built with the DEBUG macro defined to the compiler (refer to building a debugging configuration).

Previous to 8.10, there was a single DEBUG flag, enabled with `-dDEBUG` on the command line. Now there are several debugging flags to allow more selective debugging information to be printed containing only what is needed to investigate particular areas. For backward compatibilty, the `-dDEBUG` option will set all of the subset switches.

`-dCCFONTDEBUG` |  | Compiled Fonts
`-dCFFDEBUG` |  | CFF Fonts
`-dCMAPDEBUG` |  | CMAP
`-dDOCIEDEBUG` |  | CIE color
`-dEPSDEBUG` |  | EPS handling
`-dFAPIDEBUG` |  | Font API
`-dINITDEBUG` |  | Initialization
`-dPDFDEBUG` |  | PDF Interpreter
`-dPDFOPTDEBUG` |  | PDF Optimizer (Linearizer)
`-dPDFWRDEBUG` |  | PDF Writer
`-dSETPDDEBUG` |  | setpagedevice
`-dSTRESDEBUG` |  | Static Resources
`-dTTFDEBUG` |  | TTF Fonts
`-dVGIFDEBUG` |  | ViewGIF
`-dVJPGDEBUG` |  | ViewJPEG

The `-Z` and `-T` switches apply only if the interpreter was built for a debugging configuration. In the table below, the first column is a debugging switch, the second is an equivalent switch (if any) and the third is its usage.

Switches used in debugging
Switch |  | Equivalent |  |
`-A` |  | `-Z@` |  | Fill empty storage with a distinctive bit pattern for debugging
`-A-` |  | `-Z-@` |  | Turn off `-A`
`-B` size |  |  |  | Run all subsequent files named on the command line (except for `-F`) through the run_string interface, using a buffer of size bytes
`-B-` |  |  |  | Turn off `-B`: run subsequent files (except for `-F`) directly in the normal way
`-E` |  | `-Z#` |  | Turn on tracing of error returns from operators
`-E-` |  | `-Z-#` |  | Turn off `-E`
`-F` file |  |  |  | Execute the file with `-B1` temporarily in effect
`-K` n |  |  |  | Limit the total amount of memory that the interpreter can have allocated at any one time to nK bytes. n is a positive decimal integer.
`-M` n |  |  |  | Force the interpreter's allocator to acquire additional memory in units of nK bytes, rather than the default (currently 20K on DOS systems, 50K on Unix). n is a positive decimal integer, on DOS systems no greater than 63.
`-N` n |  |  |  | Allocate space for nK names, rather than the default (normally 64K). n may be greater than 64 only if `EXTEND_NAMES` was defined when the interpreter was compiled .
`-Z` xxx `-Z-`xxx |  |  |  | Turn debugging printout on (off). Each of the xxx characters selects an option. Case is significant: "a" and "A" have different meanings. `0` garbage collector, minimal detail `1` type 1 and type 42 font interpreter `2` curve subdivider/rasterizer `3` curve subdivider/rasterizer, detail `4` garbage collector (strings) `5` garbage collector (strings, detail) `6` garbage collector (chunks, roots) `7` garbage collector (objects) `8` garbage collector (refs) `9` garbage collector (pointers) `a` allocator (large blocks only) `A` allocator (all calls) `b` bitmap image processor `B` bitmap images, detail `c` color/halftone mapper `d` dictionary put/undef `D` dictionary lookups `e` external (OS-related) calls `f` fill algorithm (summary) `F` fill algorithm (detail) `g` gsave/grestore[all] `h` halftone renderer `H` halftones, every pixel `i` interpreter, just names `I` interpreter, everything `j` (Japanese) composite fonts `k` character cache and xfonts `K` character cache, every access `l` command lists, bands `L` command lists, everything `m` makefont and font cache `n` name lookup (new names only) `o` outliner (stroke) `O` stroke detail `p` band list paths `P` all paths `q` clipping `r` arc renderer `s` streams `S` scanner `t` tiling algorithm `u` undo saver (for save/restore), finalization `U` undo saver, more detail `v` alpha/transparency `V` alpha/transparency, more detail `w` compression encoder/decoder `x` transformations `y` Type 1 hints `Y` Type 1 hints, every access `z` trapezoid fill `#` operator error returns `%` externally processed comments `*` image and RasterOp parameters `:` command list and allocator/time summary `~` math functions and Functions `'` contexts, create/destroy `"` contexts, every operation `^` reference counting `_` high-level output `|` (reserved for experimental code) The following switch affects what is printed, but does not select specific items for printing: `/` include file name and line number on all trace output These switches select debugging options other than what should be printed: `$` set unused parts of object references to identifiable garbage values `+` use minimum-size stack blocks `,` don't use path-based banding ``` don't use high-level banded images `.` use small-memory table sizes even on large-memory machines `?` validate pointers before, during and after garbage collection, also before and after save and restore; also make other allocator validity checks `@` fill newly allocated, garbage-collected, and freed storage with a marker (a1, c1, and f1 respectively)
`-T` xxx `-T-`xxx |  |  |  | Turn Visual Trace on (off). Each of the xxx characters selects an option. Case is significant: "f" and "F" have different meanings. `f` the filling algorithm with characters `F` the filling algorithm with non-character paths `h` the Type 1 hinter `s` the shading algorithm `S` the stroking algorithm

#### Visual Trace

Visual Trace allows to view internal Ghostscript data in a graphical form while execution of C code. Special instructions to be inserted into C code for generating the output. Client application rasterizes it into a window.

Currently the rasterization is implemented for Windows only, in clients gswin32.exe and gswin32c.exe. They open Visual Trace window when graphical debug output appears, `-T` switch is set, and Ghostscript was built with DEBUG option. There are two important incompletenesses of the implementation :

1. The graphical output uses a hardcoded scale. An advanced client would provide a scale option via user interface.

2. Breaks are not implemented in the client. If you need a step-by-step view, you should use an interactive C debugger to delay execution at breakpoints.

## Appendix: Paper sizes known to Ghostscript

The paper sizes known to Ghostscript are defined at the beginning of the initialization file `gs_statd.ps`; see the comments there for more details about the definitions. The table here lists them by name and size. `gs_statd.ps` defines their sizes exactly in points, and the dimensions in inches (at 72 points per inch) and centimeters shown in the table are derived from those, rounded to the nearest 0.1 unit. A guide to international paper sizes can be found at

> http://www.twics.com/~eds/paper/

Paper sizes known to Ghostscript
U.S. standard
|  | Inches |  | mm |  | Points |  |
Name |  | W | × | H |  | W | × | H |  | W | × | H |  |
11x17 |  | 11.0 |  | 17.0 |  | 279 |  | 432 |  | 792 |  | 1224 |  | 11×17in portrait
ledger |  | 17.0 |  | 11.0 |  | 432 |  | 279 |  | 1224 |  | 792 |  | 11×17in landscape
legal |  | 8.5 |  | 14.0 |  | 216 |  | 356 |  | 612 |  | 1008 |  |
letter |  | 8.5 |  | 11.0 |  | 216 |  | 279 |  | 612 |  | 792 |  |
lettersmall |  | 8.5 |  | 11.0 |  | 216 |  | 279 |  | 612 |  | 792 |  |
archE |  | 36.0 |  | 48.0 |  | 914 |  | 1219 |  | 2592 |  | 3456 |  |
archD |  | 24.0 |  | 36.0 |  | 610 |  | 914 |  | 1728 |  | 2592 |  |
archC |  | 18.0 |  | 24.0 |  | 457 |  | 610 |  | 1296 |  | 1728 |  |
archB |  | 12.0 |  | 18.0 |  | 305 |  | 457 |  | 864 |  | 1296 |  |
archA |  | 9.0 |  | 12.0 |  | 229 |  | 305 |  | 648 |  | 864 |  |
ISO standard
a0 |  | 33.1 |  | 46.8 |  | 841 |  | 1189 |  | 2384 |  | 3370 |  |
a1 |  | 23.4 |  | 33.1 |  | 594 |  | 841 |  | 1684 |  | 2384 |  |
a2 |  | 16.5 |  | 23.4 |  | 420 |  | 594 |  | 1191 |  | 1684 |  |
a3 |  | 11.7 |  | 16.5 |  | 297 |  | 420 |  | 842 |  | 1191 |  |
a4 |  | 8.3 |  | 11.7 |  | 210 |  | 297 |  | 595 |  | 842 |  |
a4small |  | 8.3 |  | 11.7 |  | 210 |  | 297 |  | 595 |  | 842 |  |
a5 |  | 5.8 |  | 8.3 |  | 148 |  | 210 |  | 420 |  | 595 |  |
a6 |  | 4.1 |  | 5.8 |  | 105 |  | 148 |  | 297 |  | 420 |  |
a7 |  | 2.9 |  | 4.1 |  | 74 |  | 105 |  | 210 |  | 297 |  |
a8 |  | 2.1 |  | 2.9 |  | 52 |  | 74 |  | 148 |  | 210 |  |
a9 |  | 1.5 |  | 2.1 |  | 37 |  | 52 |  | 105 |  | 148 |  |
a10 |  | 1.0 |  | 1.5 |  | 26 |  | 37 |  | 73 |  | 105 |  |
isob0 |  | 39.4 |  | 55.7 |  | 1000 |  | 1414 |  | 2835 |  | 4008 |  |
isob1 |  | 27.8 |  | 39.4 |  | 707 |  | 1000 |  | 2004 |  | 2835 |  |
isob2 |  | 19.7 |  | 27.8 |  | 500 |  | 707 |  | 1417 |  | 2004 |  |
isob3 |  | 13.9 |  | 19.7 |  | 353 |  | 500 |  | 1001 |  | 1417 |  |
isob4 |  | 9.8 |  | 13.9 |  | 250 |  | 353 |  | 709 |  | 1001 |  |
isob5 |  | 6.9 |  | 9.8 |  | 176 |  | 250 |  | 499 |  | 709 |  |
isob6 |  | 4.9 |  | 6.9 |  | 125 |  | 176 |  | 354 |  | 499 |  |
c0 |  | 36.1 |  | 51.1 |  | 917 |  | 1297 |  | 2599 |  | 3677 |  |
c1 |  | 25.5 |  | 36.1 |  | 648 |  | 917 |  | 1837 |  | 2599 |  |
c2 |  | 18.0 |  | 25.5 |  | 458 |  | 648 |  | 1298 |  | 1837 |  |
c3 |  | 12.8 |  | 18.0 |  | 324 |  | 458 |  | 918 |  | 1298 |  |
c4 |  | 9.0 |  | 12.8 |  | 229 |  | 324 |  | 649 |  | 918 |  |
c5 |  | 6.4 |  | 9.0 |  | 162 |  | 229 |  | 459 |  | 649 |  |
c6 |  | 4.5 |  | 6.4 |  | 114 |  | 162 |  | 323 |  | 459 |  |
JIS standard
jisb0 |  |  |  |  |  | 1030 |  | 1456 |  |  |  |  |  |
jisb1 |  |  |  |  |  | 728 |  | 1030 |  |  |  |  |  |
jisb2 |  |  |  |  |  | 515 |  | 728 |  |  |  |  |  |
jisb3 |  |  |  |  |  | 364 |  | 515 |  |  |  |  |  |
jisb4 |  |  |  |  |  | 257 |  | 364 |  |  |  |  |  |
jisb5 |  |  |  |  |  | 182 |  | 257 |  |  |  |  |  |
jisb6 |  |  |  |  |  | 128 |  | 182 |  |  |  |  |  |
ISO/JIS switchable
b0 (see * below)
b1 (see * below)
b2 (see * below)
b3 (see * below)
b4 (see * below)
b5 (see * below)
Other
flsa |  | 8.5 |  | 13.0 |  | 216 |  | 330 |  | 612 |  | 936 |  | U.S. foolscap
flse |  | 8.5 |  | 13.0 |  | 216 |  | 330 |  | 612 |  | 936 |  | European foolscap
halfletter |  | 5.5 |  | 8.5 |  | 140 |  | 216 |  | 396 |  | 612 |  |

*Note: Initially the B paper sizes are the ISO sizes, e.g., `b0` is the same as `isob0`. Running the file `lib/jispaper.ps` makes the B paper sizes be the JIS sizes, e.g., `b0` becomes the same as `jisb0`.

## Appendix: X default font mappings

### Standard X servers

#### Regular fonts

        AvantGarde-Book:              -Adobe-ITC Avant Garde Gothic-Book-R-Normal--\n\
        AvantGarde-BookOblique:       -Adobe-ITC Avant Garde Gothic-Book-O-Normal--\n\
        AvantGarde-Demi:              -Adobe-ITC Avant Garde Gothic-Demi-R-Normal--\n\
        AvantGarde-DemiOblique:       -Adobe-ITC Avant Garde Gothic-Demi-O-Normal--\n\
        Bookman-Demi:                 -Adobe-ITC Bookman-Demi-R-Normal--\n\
        Bookman-DemiItalic:           -Adobe-ITC Bookman-Demi-I-Normal--\n\
        Bookman-Light:                -Adobe-ITC Bookman-Light-R-Normal--\n\
        Bookman-LightItalic:          -Adobe-ITC Bookman-Light-I-Normal--\n\
        Courier:                      -Adobe-Courier-Medium-R-Normal--\n\
        Courier-Bold:                 -Adobe-Courier-Bold-R-Normal--\n\
        Courier-BoldOblique:          -Adobe-Courier-Bold-O-Normal--\n\
        Courier-Oblique:              -Adobe-Courier-Medium-O-Normal--\n\
        Helvetica:                    -Adobe-Helvetica-Medium-R-Normal--\n\
        Helvetica-Bold:               -Adobe-Helvetica-Bold-R-Normal--\n\
        Helvetica-BoldOblique:        -Adobe-Helvetica-Bold-O-Normal--\n\
        Helvetica-Narrow:             -Adobe-Helvetica-Medium-R-Narrow--\n\
        Helvetica-Narrow-Bold:        -Adobe-Helvetica-Bold-R-Narrow--\n\
        Helvetica-Narrow-BoldOblique: -Adobe-Helvetica-Bold-O-Narrow--\n\
        Helvetica-Narrow-Oblique:     -Adobe-Helvetica-Medium-O-Narrow--\n\
        Helvetica-Oblique:            -Adobe-Helvetica-Medium-O-Normal--\n\
        NewCenturySchlbk-Bold:        -Adobe-New Century Schoolbook-Bold-R-Normal--\n\
        NewCenturySchlbk-BoldItalic:  -Adobe-New Century Schoolbook-Bold-I-Normal--\n\
        NewCenturySchlbk-Italic:      -Adobe-New Century Schoolbook-Medium-I-Normal--\n\
        NewCenturySchlbk-Roman:       -Adobe-New Century Schoolbook-Medium-R-Normal--\n\
        Palatino-Bold:                -Adobe-Palatino-Bold-R-Normal--\n\
        Palatino-BoldItalic:          -Adobe-Palatino-Bold-I-Normal--\n\
        Palatino-Italic:              -Adobe-Palatino-Medium-I-Normal--\n\
        Palatino-Roman:               -Adobe-Palatino-Medium-R-Normal--\n\
        Times-Bold:                   -Adobe-Times-Bold-R-Normal--\n\
        Times-BoldItalic:             -Adobe-Times-Bold-I-Normal--\n\
        Times-Italic:                 -Adobe-Times-Medium-I-Normal--\n\
        Times-Roman:                  -Adobe-Times-Medium-R-Normal--\n\
        ZapfChancery-MediumItalic:    -Adobe-ITC Zapf Chancery-Medium-I-Normal--

#### Symbol fonts

        Symbol:                       -Adobe-Symbol-Medium-R-Normal--

#### Dingbat fonts

        ZapfDingbats:                 -Adobe-ITC Zapf Dingbats-Medium-R-Normal--

### Sun OpenWindows

For Sun's X11/NeWS one can use the OpenWindows scalable fonts instead, which gives good output for any point size. In this environment, the relevant section of the resource file should look like this:

    Ghostscript.regularFonts: \
        AvantGarde-Book:              -itc-avantgarde-book-r-normal-- \n\
        AvantGarde-BookOblique:       -itc-avantgarde-book-o-normal-- \n\
        AvantGarde-Demi:              -itc-avantgarde-demi-r-normal-- \n\
        AvantGarde-DemiOblique:       -itc-avantgarde-demi-o-normal-- \n\
        Bembo:                        -monotype-bembo-medium-r-normal-- \n\
        Bembo-Bold:                   -monotype-bembo-bold-r-normal-- \n\
        Bembo-BoldItalic:             -monotype-bembo-bold-i-normal-- \n\
        Bembo-Italic:                 -monotype-bembo-medium-i-normal-- \n\
        Bookman-Demi:                 -itc-bookman-demi-r-normal-- \n\
        Bookman-DemiItalic:           -itc-bookman-demi-i-normal-- \n\
        Bookman-Light:                -itc-bookman-light-r-normal-- \n\
        Bookman-LightItalic:          -itc-bookman-light-i-normal-- \n\
        Courier:                      -itc-courier-medium-r-normal-- \n\
        Courier-Bold:                 -itc-courier-bold-r-normal-- \n\
        Courier-BoldOblique:          -itc-courier-bold-o-normal-- \n\
        Courier-Oblique:              -itc-courier-medium-o-normal-- \n\
        GillSans:                     -monotype-gill-medium-r-normal-sans- \n\
        GillSans-Bold:                -monotype-gill-bold-r-normal-sans- \n\
        GillSans-BoldItalic:          -monotype-gill-bold-i-normal-sans- \n\
        GillSans-Italic:              -monotype-gill-normal-i-normal-sans- \n\
        Helvetica:                    -linotype-helvetica-medium-r-normal-- \n\
        Helvetica-Bold:               -linotype-helvetica-bold-r-normal-- \n\
        Helvetica-BoldOblique:        -linotype-helvetica-bold-o-normal-- \n\
        Helvetica-Narrow:             -linotype-helvetica-medium-r-narrow-- \n\
        Helvetica-Narrow-Bold:        -linotype-helvetica-bold-r-narrow-- \n\
        Helvetica-Narrow-BoldOblique: -linotype-helvetica-bold-o-narrow-- \n\
        Helvetica-Narrow-Oblique:     -linotype-helvetica-medium-o-narrow-- \n\
        Helvetica-Oblique:            -linotype-helvetica-medium-o-normal-- \n\
        LucidaBright:                 -b&h-lucidabright-medium-r-normal-- \n\
        LucidaBright-Demi:            -b&h-lucidabright-demibold-r-normal-- \n\
        LucidaBright-DemiItalic:      -b&h-lucidabright-demibold-i-normal-- \n\
        LucidaBright-Italic:          -b&h-lucidabright-medium-i-normal-- \n\
        LucidaSans:                   -b&h-lucida-medium-r-normal-sans- \n\
        LucidaSans-Bold:              -b&h-lucida-bold-r-normal-sans- \n\
        LucidaSans-BoldItalic:        -b&h-lucida-bold-i-normal-sans- \n\
        LucidaSans-Italic:            -b&h-lucida-medium-i-normal-sans- \n\
        LucidaSans-Typewriter:        -b&h-lucidatypewriter-medium-r-normal-sans- \n\
        LucidaSans-TypewriterBold:    -b&h-lucidatypewriter-bold-r-normal-sans- \n\
        NewCenturySchlbk-BoldItalic:  -linotype-new century schoolbook-bold-i-normal-- \n\
        NewCenturySchlbk-Bold:        -linotype-new century schoolbook-bold-r-normal-- \n\
        NewCenturySchlbk-Italic:      -linotype-new century schoolbook-medium-i-normal-- \n\
        NewCenturySchlbk-Roman:       -linotype-new century schoolbook-medium-r-normal-- \n\
        Palatino-Bold:                -linotype-palatino-bold-r-normal-- \n\
        Palatino-BoldItalic:          -linotype-palatino-bold-i-normal-- \n\
        Palatino-Italic:              -linotype-palatino-medium-i-normal-- \n\
        Palatino-Roman:               -linotype-palatino-medium-r-normal-- \n\
        Rockwell:                     -monotype-rockwell-medium-r-normal-- \n\
        Rockwell-Bold:                -monotype-rockwell-bold-r-normal-- \n\
        Rockwell-BoldItalic:          -monotype-rockwell-bold-i-normal-- \n\
        Rockwell-Italic:              -monotype-rockwell-medium-i-normal-- \n\
        Times-Bold:                   -linotype-times-bold-r-normal-- \n\
        Times-BoldItalic:             -linotype-times-bold-i-normal-- \n\
        Times-Italic:                 -linotype-times-medium-i-normal-- \n\
        Times-Roman:                  -linotype-times-medium-r-normal-- \n\
        Utopia-Bold:                  -adobe-utopia-bold-r-normal-- \n\
        Utopia-BoldItalic:            -adobe-utopia-bold-i-normal-- \n\
        Utopia-Italic:                -adobe-utopia-regular-i-normal-- \n\
        Utopia-Regular:               -adobe-utopia-regular-r-normal-- \n\
        ZapfChancery-MediumItalic:    -itc-zapfchancery-medium-i-normal-- \n
    Ghostscript.dingbatFonts: \
        ZapfDingbats:                 -itc-zapfdingbats-medium-r-normal--
    Ghostscript.symbolFonts: \
        Symbol:                       --symbol-medium-r-normal--

## Running Ghostscript with 3d party font renderers

Font API (FAPI) is a new feature which allows to attach 3d party font renderers to Ghostscript. This section explains how to run Ghostscript with 3d party font renderers, such as Agfa UFST or Free Type.

Note: To run Ghostscript with Agfa UFST you need a license from Agfa. Please ignore issues about UFST if you haven't got it.

Important note: Third-party font renderers are incompatible with devices that can embed fonts in their output (such as pdfwrite), because such renderers store fonts in a form from which Ghostscript cannot get the necessary information for embedding. Ghostscript disables such renderers when such device is being used. In particular, UFST and Free Type are disabled while running Ghostscript with the `pdfwrite` device.

To run Ghostscript with Free Type, you first need to build Ghostscript with the Free Type bridge. Refer How to build Ghostscript with Free Type.

To run Ghostscript with UFST, you first need to build Ghostscript with the UFST bridge. Refer How to build Ghostscript with UFST. Both bridges may run together.

Then you need to obtain the Decoding resources from Artifex Software Inc. and install them with Ghostscript. Just copy the files to the `Resource/Decoding` directory (or to the subdirectory `Decoding` of a directory, which is specified in `GenericResourcePath`).

There are 2 ways to handle fonts with a 3d party font renderer (FAPI). First, you can substitute any FAPI-handled font to a PostScript font, using special map files. Second, you can redirect PostScript fonts to FAPI, setting entries in `lib/FAPIconfig` file.

The file `lib/FAPIfontmap` defines a map table for FAPI-handled fonts. The format of `lib/FAPIfontmap` is explained below.

Font files being handled with FAPI may reside in any directory in your hard disk. Paths to them to be specified in `lib/FAPIfontmap`. The path may be either absolute or relative. Relative ones are being resolved from the path, which is specified in `lib/FAPIconfig` file.

The file `lib/FAPIfontmap` is actually special PostScript code. It contains records for each font being rendered with FAPI. Records must end with semicolon. Each record is a pair. The first element of the pair is the font name (the name that PostScript documents use to access the font, which may differ from real name of the font which the font file defines). The second element is a dictionary with entries :

Key | Type | Description
--- | --- | ---
Path | string | Absolute path to font file, or relative path to font file from the FontPath value, being specified in `lib/FAPIconfig`.
FontType | interger | PostScript type for this font. Only 1 and 42 are currently allowed. Note that this is unrelated to the real type of the font file - the bridge will perform a format conversion.
FAPI | name | Name of the renderer to be used with the font. Only `/AgfaUFST` and `/FreeType` are now allowed.
SubfontId | integer | (optional) Index of the font in font collection, such as FCO or TTC. It is being ignored if Path doesn't specify a collection. Note that Free Type can't handle FCO. Default value is 0.
Decoding | name | (optional) The name of a Decoding resource to be used with the font. If specified, `lib/xlatmap` (see below) doesn't work for this font.

Example of FAPI font map record :

> `/FCO1 << /Path (/AFPL/Agfa/fontdata/MTFONTS/PCLPS3/MT1/PCLP3__F.fco) /FontType 1 /FAPI /AgfaUFST >> ;`

Note that `lib/FAPIfontmap` specifies only instances of Font category. CID fonts to be listed in another map file.

The file `lib/FAPIcidfmap` defines a mapping table for CIDFont resources. It contains records for each CID font being rendered with FAPI. The format is similar to `lib/FAPIfontmap`, but dictionaries must contain few different entries :

Key | Type | Description
--- | --- | ---
Path | string | Absolute path to font file, or relative path to font file from the CIDFontPath value, being specified in `lib/FAPIconfig`.
CIDFontType | interger | PostScript type for this CID font. Only 0, 1 and 2 are currently allowed. Note that this is unrelated to the real type of the font file - the bridge will perform format conversion.
FAPI | name | Name of the renderer to be used with the font. Only `/AgfaUFST` and `/FreeType` are now allowed.
SubfontId | integer | (optional) Index of the font in font collection, such as FCO or TTC. It is being ignored if Path doesn't specify a collection. Default value is 0.
CSI | array of 2 elements | (required) Information for building `CIDSystemInfo`. The first element is a string, which specifies `Ordering`. The second element is a number, which specifies `Supplement`.

Example of FAPI CID font map record :

> `/HeiseiKakuGo-W5 << /Path (/WIN2000/Fonts/PMINGLIU.TTF) /CIDFontType 0 /FAPI /AgfaUFST /CSI [(Japan1) 2] >> ;`

The control file `lib/FAPIconfig` defines 4 entries :

Key | Type | Description
--- | --- | ---
FontPath | string | Absolute path to a directory, which contains fonts. Used to resolve relative paths in `lib/FAPIfontmap`.
CIDFontPath | string | Absolute path to a directory, which contains fonts to substitute to CID fonts. Used to resolve relative paths in `lib/FAPIcidfmap`. It may be same or different than FontPath.
HookDiskFonts | array of integers. | List of PS font types to be handled with FAPI. This controls other fonts that ones listed in `lib/FAPIfontmap` and `lib/FAPIcidfmap` - such ones are PS fonts installed to Ghostscript with `lib/fontmap` or with `GS_FONTPATH`, or regular CID font resources. Unlisted font types will be rendered with the native Ghostscript font renderer. Only allowed values now are 1,9,11,42. Note that 9 and 11 correspond to CIDFontType 0 and 2.
HookEmbeddedFonts | array of integers. | List of PS font types to be handled with FAPI. This controls fonts being embedded into a document - either fonts or CID font resources. Unlisted font types will be rendered with the native Ghostscript font renderer. Only allowed values now are 1,9,11,42. Note that 9 and 11 correspond to CIDFontType 0 and 2.

You may need to customize the file `lib/xlatmap`. Follow instructions in it.

Note that UFST and Free Type cannot handle some Ghostscript fonts because they does not include a PostScript interpreter and therefore has stronger restrictions on font formats than Ghostscript itself does. If their font types are listed in HookDiskFonts or in HookEmbeddedFonts, Ghostscript interpret them as PS files, then serializes font data into a RAM buffer and passes it to FAPI as PCLEOs.

Copyright © 2000-2006 artofcode LLC. All rights reserved.

This software is provided AS-IS with no warranty, either express or implied. This software is distributed under license and may not be copied, modified or distributed except as expressly authorized under the terms of that license. Refer to licensing information at http://www.artifex.com/ or contact Artifex Software, Inc., 7 Mt. Lassen Drive - Suite A-134, San Rafael, CA 94903, U.S.A., +1(415)492-9861, for further information.

Ghostscript version 8.54, 17 May 2006