     [file macros.texi not included]

dvipng
******

This manual documents dvipng, a program to translate a DVI (DeVice Independent) file into PNG (Portable Network Graphics).

This file documents dvipng version 1.17

Corrections or perhaps rewrites of sections are very welcome.

Jan-Åke Larsson

Introduction
************

     [file readme.texi not included]

Installation
************

     [file install.texi not included]

Basic usage of dvipng
*********************

To use dvipng at its simplest, simply type

     dvipng foo

where foo.dvi is the output of TeX that you want to convert to PNG format. If there are four pages in foo.dvi, those pages will be output as foo1.png, foo2.png, foo3.png, and foo4.png, respectively.

If you have enabled the PostScript font support (via FreeType), fonts will be rendered as they are needed. Otherwise, dvipng will use bitmapped (PK) fonts, and if you use PK fonts that have not been used on your system before, they may be automatically generated; this process can take a few minutes, so progress reports appear by default. The next time the same font is used, it will have been saved on disk, so rendering will go much faster. (If dvipng tries to endlessly generate the same fonts over and over again, something is wrong. See Unable to generate fonts (Kpathsea).)

Many options are available (see the next section).  For a brief summary of available options, just type

     dvipng --help

Command-line options
********************

dvipng has a plethora of command line options.  Reading through this section will give a good idea of the capabilities of the driver.

Option summary
==============

Here is a handy summary of the options; it is printed out when you run dvipng with no arguments or with the standard --help option.

          [file dvipng.help not included]

Option details
==============

Many of the parameterless options listed here can be turned off by suffixing the option with a zero (0); for instance, to turn off page reversal, use -r0.  Such options are marked with a trailing *.

-
     Read additional options from standard input after processing the command line.

--help
     Print a usage message and exit.

--version
     Print the version number and exit.

-bd NUM

-bd COLOR_SPEC

-bd 'NUM COLOR_SPEC'
     Set the pixel width of the transparent border (default 0). Using this option will make the image edges transparent, but it only affects pixels with the background color. Giving a COLOR_SPEC will set the fallback color, to be used in viewers that cannot handle transparency (the default is the background color). The color spec should be in TeX color \special syntax, e.g., 'rgb 1.0 0.0 0.0'. Setting the fallback color makes the default border width 1 px. See Color.

--bdpi NUM
     This option only has an effect when using bitmapped (PK) fonts. The option sets the base (Metafont) resolution, both horizontal and vertical, to NUM dpi (dots per inch). This option is necessary when manually selecting Metafont mode with the --mode option (see below).

-bg COLOR_SPEC
     Choose background color for the images. This option will be ignored if there is a background color \special in the DVI. The color spec should be in TeX color \special syntax, e.g., 'rgb 1.0 0.0 0.0'. You can also specify 'Transparent' or 'transparent' which will give you a transparent background with the normal background as a fallback color. A capitalized 'Transparent' will give a full-alpha transparency, while an all-lowercase 'transparent' will give a simple fully transparent background with non-transparent antialiased pixels. The latter would be suitable for viewers who cannot cope with a true alpha channel.  GIF images do not support full alpha transparency, so in case of GIF output, both variants will use the latter behaviour.  See Color.

-d NUM
     Set the debug flags, showing what dvipng (thinks it) is doing. This will work unless dvipng has been compiled without the DEBUG option (not recommended). Set the flags as you need them, use -d -1 as the first option for maximum output. See Debug options.

-D NUM
     Set the output resolution, both horizontal and vertical, to NUM dpi (dots per inch).

     One may want to adjust this to fit a certain text font size (e.g., on a web page), and for a text font height of FONT_PX pixels (in Mozilla) the correct formula is

          DPI = FONT_PX * 72.27 / 10 [px * TeXpt/in / TeXpt]

     The last division by ten is due to the standard font height 10pt in your document, if you use 12pt, divide by 12. Unfortunately, some proprietary browsers have font height in pt (points), not pixels. You have to rescale that to pixels, using the screen resolution (default is usually 96 dpi) which means the formula is

          FONT_PX = FONT_PT * 96 / 72 [pt * px/in / (pt/in)]

     On some high-res screens, the value is instead 120 dpi. Good luck!

--depth*
     Report the depth of the image. This only works reliably when the LaTeX style preview.sty from previewlatex is used with the active option. It reports the number of pixels from the bottom of the image to the baseline of the image. This can be used for vertical positioning of the image in, e.g., web documents, where one would use (Cascading StyleSheets 1)

          <IMG SRC="FILENAME.PNG" STYLE="vertical-align: -DEPTHpx">

     The depth is a negative offset in this case, so the minus sign is necessary, and the unit is pixels (px).

--dvinum*
     Set this option to make the output page number be the TeX page numbers rather than the physical page number. See the -o switch.

-fg COLOR_SPEC
     Choose foreground color for the images. This option will be ignored if there is a foreground color \special in the DVI. The color spec should be in TeX color \special syntax, e.g., 'rgb 1.0 0.0 0.0'. See Color.

--follow*
     Wait for data at end-of-file. One of the benefits of dvipng is that it does not read the postamble, so it can be started before TeX finishes. This switch makes dvipng wait at end-of-file for further output, unless it finds the POST marker that indicates the end of the DVI. This is similar to tail -f but for DVI-to-PNG conversion.

--freetype*
     Enable/disable FreeType font rendering (default on). This option is available if the FreeType2 font library was present at compilation time. If this is the case, dvipng will have direct support for PostScript Type1 and TrueType fonts internally, rather than using gsftopk for rendering the fonts. If you have PostScript versions of Computer Modern installed, there will be no need to generate bitmapped (PK) variants on disk of these. Then, you can render images at different (and unusual) resolutions without cluttering the disk with lots of bitmapped fonts. One reason to disable FreeType font rendering would be to generate identical output on different platforms, since FreeType uses the native renderer and therefore can give slightly different output on each platform.

--gamma NUM
     Control the interpolation of colors in the greyscale anti-aliasing color palette.  Default value is 1.0.  For 0 < NUM < 1, the fonts will be lighter (more like the background), and for NUM > 1, the fonts will be darker (more like the foreground).

--gif*
     The images are output in the GIF format, if GIF support is enabled. This is the default for the dvigif binary, which only will be available when GIF support is enabled. GIF images are palette images (see the --palette option) and does not support true alpha channels (see the --bg option). See also the --png option.

--height*
     Report the height of the image. This only works reliably when the LaTeX style preview.sty from previewlatex is used with the active option. It reports the number of pixels from the top of the image to the baseline of the image. The total height of the image is obtained as the sum of the values reported from --height and --depth.

-l [=]NUM
     The last page printed will be the first one numbered NUM. Default is the last page in the document.  If NUM is prefixed by an equals sign, then it (and the argument to the -p option, if specified) is treated as a physical (absolute) page number, rather than a value to compare with the TeX \count0 values stored in the DVI file. Thus, using -l =9 will end with the ninth page of the document, no matter what the pages are actually numbered.

--mode MODE
     This option only has an effect when using bitmapped (PK) fonts. Use MODE as the Metafont device name for the PK fonts (both for path searching and font generation). This needs to be augmented with the base device resolution, given with the --bdpi option. See the file ftp://ftp.tug.org/tex/modes.mf for a list of resolutions and mode names for most devices. See Unable to generate fonts (Kpathsea).

-M*
     This option only has an effect when using bitmapped (PK) fonts. It turns off automatic PK font generation (mktexpk).

--nogs*
     This switch prohibits the internal call to GhostScript for displaying PostScript specials. --nogs0 turns the call back on.

--nogssafer*
     Normally, if GhostScript is used to render PostScript specials, the GhostScript interpreter is run with the option -dSAFER. The --nogssafer option runs GhostScript without -dSAFER. The -dSAFER option in Ghostscript disables PostScript operators such as deletefile, to prevent possibly malicious PostScript programs from having any effect.

--norawps*
     Some packages generate raw PostScript specials, even non-rendering such specials.  This switch turns off the internal call to GhostScript intended to display these raw PostScript specials. --norawps0 turns the call back on.

-o NAME
     Send output to the file NAME. A single occurrence of %d or %01d, ..., %09d will be exchanged for the physical page number (this can be changed, see the --dvinum switch). The default output filename is FILE%d.png where the input DVI file was FILE.dvi.

-O X-OFFSET,Y-OFFSET
     Move the origin by X-OFFSET,Y-OFFSET, a comma-separated pair of dimensions such as .1in,-.3cm. The origin of the page is shifted from the default position (of one inch down, one inch to the right from the upper left corner of the paper) by this amount.

-p [=]NUM
     The first page printed will be the first one numbered NUM. Default is the first page in the document.  If NUM is prefixed by an equals sign, then it (and the argument to the -l option, if specified) is treated as a physical (absolute) page number, rather than a value to compare with the TeX \count0 values stored in the DVI file.  Thus, using -p =3 will start with the third page of the document, no matter what the pages are actually numbered.

--palette*
     When an external image is included, dvipng will automatically switch to truecolor mode, to avoid unnecessary delay and quality reduction, and enable the EPS translator to draw on a transparent background and outside of the boundingbox. This switch will force palette (256-color) output and make dvipng revert to opaque clipped image inclusion. This will also override the --truecolor switch if present.

--picky*
     No images are output when a warning occurs. Normally, dvipng will output an image in spite of a warning, but there may be something missing in this image. One reason to use this option would be if you have a more complete but slower fallback converter. Mainly, this is useful for failed figure inclusion and unknown \special occurrences, but warnings will also occur for missing or unknown color specs and missing PK fonts.

--png*
     The images are output in the PNG format. This is the default for the dvipng binary. See also the --gif option.

-pp FIRSTPAGE-LASTPAGE
     Print pages FIRSTPAGE through LASTPAGE; but not quite equivalent to -p FIRSTPAGE -l LASTPAGE. For example, when rendering a book, there may be several instances of a page in the DVI file (one in \frontmatter, one in \mainmatter, and one in \backmatter). In case of several pages matching, -pp FIRSTPAGE-LASTPAGE will render all pages that matches the specified range, while -p FIRSTPAGE -l LASTPAGE will render the pages from the first occurrence of FIRSTPAGE to the first occurrence of LASTPAGE. This is the (undocumented) behaviour of dvips. In dvipng you can give both kinds of options, in which case you get all pages that matches the range in -pp between the pages from -p to -l. Also multiple -pp options accumulate, unlike -p and -l. The - separator can also be :. Note that -pp -1 will be interpreted as "all pages up to and including 1", if you want a page numbered -1 (only the table of contents, say) put -pp -1--1, or more readable, -pp -1:-1.

-q*
     Run quietly.  Don't chatter about pages converted, etc. to standard output; report no warnings (only errors) to standard error.

-Q NUM
     Set the quality to NUM. That is, choose the number of antialiasing levels for bitmapped fonts (PK), to be NUM*NUM+1. The default value is 4 which gives 17 levels of antialiasing for antialiased fonts from these two. If FreeType is available, its rendering is unaffected by this option.

-r*
     Toggle output of pages in reverse/forward order. By default, the first page in the DVI is output first.

--strict*
     The program exits when a warning occurs. Normally, dvipng will output an image in spite of a warning, but there may be something missing in this image. One reason to use this option would be if you have a more complete but slower fallback converter. See the --picky option above for a list of when warnings occur.

-T IMAGE_SIZE
     Set the image size to IMAGE_SIZE which can be either of bbox, tight, or a comma-separated pair of dimensions HSIZE,VSIZE such as .1in,.3cm. The default is bbox which produces a PNG that includes all ink put on the page and in addition the DVI origin, located 1in from the top and 1in from the left edge of the paper. This usually gives whitespace above and to the left in the produced image. The value tight will make dvipng only include all ink put on the page, producing neat images.

--truecolor*
     This will make dvipng generate truecolor output. Note that truecolor output is automatic if you include an external image in your DVI, e.g., via a PostScript special (i.e., the graphics or graphicx package). This switch is overridden by the --palette switch.

-v*
     Enable verbose operation. This will currently indicate what fonts is used, in addition to the usual output.

--width*
     Report the width of the image. See also --height and --depth.

-x NUM
     This option is deprecated; it should not be used. It is much better to select the output resolution directly with the -D option. This option sets the magnification ratio to NUM/1000 and overrides the magnification specified in the DVI file.  Must be between 10 and 100000.  It is recommended that you use standard magstep values (1095, 1200, 1440, 1728, 2074, 2488, 2986, and so on) to help reduce the total number of PK files generated.  NUM may be a real number, not an integer, for increased precision.

-z NUM
     Set the PNG compression level to NUM. This option is enabled if your libgd is new enough. The default compression level is 1, which selects maximum speed at the price of slightly larger PNGs. For an older libgd, the hard-soldered value 5 is used. The include file png.h says

          Currently, valid values range from 0 - 9, corresponding directly to the zlib compression levels 0 - 9 (0 - no compression, 9 - "maximal" compression). Note that tests have shown that zlib compression levels 3-6 usually perform as well as level 9 for PNG images, and do considerably fewer calculations. In the future, these values may not correspond directly to the zlib compression levels.

Graphics
********

dvipng attempts to handle graphics as included by the graphicx and graphics packages, without the need of specifying a driver to these packages. This means that it recognizes the encapsulated postscript inclusion meant for dvips, but is also able (from version 1.8) to include bitmapped graphics. It also tries to handle some of the raw PostScript that is output from various packages. Some of the possibilities and problems are mentioned below.

Encapsulated PostScript
=======================

When an EPS file is included, a call to GhostScript is performed to produce a bitmapped image that can be included. The default is to produce an image with transparent background, at the same size as the DVI page currently being converted to PNG, and include that as foreground on the PNG. Of course, if the image is to be cropped, that is done. The included image will be a truecolor image, so for maximum performance the output PNG will be in truecolor mode as well.

This conversion needs the pngalpha output device to be present in your copy of GhostScript. If that device is not present, or you use the --palette switch or request GIF output, the fallback is to use the png16m device to produce a cropped opaque image for inclusion. Other relevant switches are --noghostscript and --nogssafer. See Option details.

The most common problem with including graphics is an incorrect bounding box. Complain to whoever wrote the software that generated the file if the bounding box is indeed incorrect. An adjusted boundingbox can be specified in the \includegraphics call, as in this example (using graphicx):

     \includegraphics[bb=10 20 100 200]{imagename.eps}

Bitmapped graphics
==================

dvipng can include PNG, JPEG and GIF graphics. When including such images via \includegraphics you need to specify the bounding box since TeX itself cannot read them from the files in question. The bounding box size should be given as 0 0 w h in pixels, e.g., if the file imagename.png is 300x400 pixels, the inclusion would read

     \includegraphics[bb=0 0 300 400]{imagename.png}

The default size is the image size in bp (``big points'' in TeX nomenclature or PostScript points as other people have it, 72 per inch). That is, default resolution will be 72 dpi for included bitmaps, which is the default size in the few other bitmap-capable drivers that are known to me (dvipdfm and PDFLaTeX).

If you want 100 dpi you need to specify the width accordingly. You just divide your image width by 100: a 135 pixel wide image at 100 dpi will take up 1.35 inches. If you want 200 dpi you divide by 200, and so on. Simple, eh? The example above at 200 dpi would be 1.5 inches wide:

     \includegraphics[bb=0 0 300 400,witdh=1.5in]{imagename.png}

Raw PostScript
==============

dvipng attempts to handle raw PostScript. Rendering raw PostScript specials is done on top of the page by including a transparent image generated by the pngalpha device in GhostScript (automatically selecting truecolor mode in dvipng).

Included PostScript headers are respected, and if the header tex.pro is included, dvipng also throws in color.pro and special.pro. The package xcolor includes its own headers with color names, and this is not only kept as a PostScript header, but is also read and interpreted by dvipng itself. An attempt is also made to respect the PGF header. The non-rendering specials from hyperref are handled via some heuristics and do not give an error.

Really rendering and moving things with raw PostScript specials is more troublesome. The \rotatebox macro serves as a good example. The dvips driver of the graphicx package surrounds DVI glyphs with PostScript code so that after conversion by dvips, the glyphs (now themselves in PostScript) will be rotated in the desired way. dvipng does not handle this, at present. An attempt has been made to handle the rendering specials output by PGF (tikz), and also PSTricks. Some things work, but others do not.  This is especially clear when mixing PostScript and DVI rendering commands such as glyphs. dvipng cannot at present detect if PostScript code moves currentpoint or rotates the frame since GhostScript does not return such information. A recommendation would be to produce images from these packages as EPS files and include them into your document in the standard manner.

Another way to handle this would be to use a slower fallback (with dvips and gs, for example). If you want to disable raw PostScript handling in dvipng, use the switch --norawps.  This switch turns off the internal call to GhostScript intended to display these raw PostScript specials. Further, when dvipng encounters raw PostScript and the gs call is turned off, it gives a warning. It is now possible to use the switch --picky to disable page rendering of pages with warnings, and use the slower fallback for these pages.

Color
*****

To support color, dvipng recognizes a certain set of specials as generated by the color and xcolor style files. These specials start with the keyword color or the keyword background, followed by a color specification.

Color specifications
====================

The color specification supported by dvipng is by-value or by-name. The by-value spec starts with the name of a color model (one of rgb, hsb, cmy, cmyk, or gray) followed by the appropriate number of parameters. Thus, the color specification rgb 0.3 0.4 0.5 would correspond to the color that is 0.3 0.4 0.5 in its red, blue and green values. The color model used internally in dvipng is RGB (discretized to 256 levels), for details on the formulas used in conversion, see the xcolor documentation.

By-name color specifications are single (case-dependent) words and are compared with color names defined in dvipsnam.def (from the graphics bundle), svgnam.def and xcolor.sty (from the xcolor bundle). See the xcolor documentation for a list of names and the corresponding colors.

On the command-line, the name Transparent can also be used as an argument to --bg to choose transparent background. See Option details.

Color specials
==============

We will describe background first, since it is the simplest. The background keyword must be followed by a color specification. That color specification is used as a fill color for the background. The last background special on a page is the one that gets used, and is used for the whole of the page image. (This is possible because the prescan phase of dvipng notices all of the color specials so that the appropriate information can be written out during the second phase.)

The color special itself has three forms. The first is just color followed by a color specification. In this case, the current global color is set to that color; the color stack must be empty when such a command is executed.

The second form is color push followed by a color specification. This saves the current color on the color stack and sets the color to be that given by the color specification.  This is the most common way to set a color.

The final form of the color special is just color pop, with no color specification; this says to pop the color last pushed on the color stack from the color stack and set the current color to be that color.

dvipng correctly handles these color specials across pages, even when the pages are rendered repeatedly or in reverse order.

Diagnosing problems
*******************

You've gone through all the trouble of installing dvipng, carefully read all the instructions in this manual, and still can't get something to work. The following sections provide some helpful hints if you find yourself in such a situation.

Contact information
===================

Bug reports should be sent to dvipng@nongnu.org.

Questions, suggestions for new features, pleas for help, and/or praise should go to dvipng@nongnu.org. For more information on this mailing list, send a message with just the word `help' as subject or body to dvipng-request@nongnu.org or look at http://lists.nongnu.org/mailman/listinfo/dvipng.

Offers to support further development will be appreciated. For developer access, ask on dvipng@nongnu.org.

For details on the TeX path-searching library, and mktexpk problems, see Common problems (Kpathsea).

Debug options
=============

The -d flag to dvipng helps in tracking down certain errors.  The parameter to this flag is an integer that tells what errors are currently being tracked.  To track a certain class of debug messages, simply provide the appropriate number given below; if you wish to track multiple classes, sum the numbers of the classes you wish to track.  To track all classes, you can use -1.

Some of these debugging options are actually provided by Kpathsea (see Debugging (Kpathsea)).

The classes are:

1
     Normal dvi op-codes

2
     Virtual fonts

4
     PK fonts

8
     TFM files

16
     Glyph rendering

32
     FreeType calls

64
     Encoding loads

128
     Color specials

256
     GhostScript specials

512
     Kpathsea stat calls

1024
     Kpathsea hash table lookups

2048
     Kpathsea path element expansion

4096
     Kpathsea path searches

Credits
*******

A number of persons have contributed, if I forget to mention someone, I apologize. First and foremost we have David Kastrup whose previewlatex project provided the incentive to write this program. There is also a number of people who have contributed by reporting bugs and suggesting improvements as the thing has evolved. These include but is perhaps not limited to (in semi-random order): Thomas Esser (teTeX), Christian Schenk (MIKTeX), Brian R Furry (debian package), Angus Leeming (LyX), Thomas Boutell (libgd), John Jones (first user report), Uwe Kern (xcolor), Karl Berry and Peter Breitenlohner (TeX Live), David Harvey (hinting in Freetype), Neal Harmon, Alan Shutko, Reiner Stieb, Nick Alcock, Adam Buchbinder, Svend Tollak Munkejord, James Longstreet, Bernhard Simon, Bob McElrath, Georg Schwarz, Jason Farmer, Brian V. Smith, Samuel Hathaway, Thomas R. Shemanske, Stephen Gibson, Christian Ridderström, Ezra Peisach, William H Wheeler, Thomas Klausner, Harald Koenig, Adrian Bunk, Kevin Smith, Jason Riedy, Wolfram Krause, Reinhard Kotucha, Takeshi Abe, Waldeck Schutzer, Ahzo, and Andy Nguyen.

Copying
*******

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this program. If not, see <http://www.gnu.org/licenses/>.

Copyright © 2002-2015, 2019 Jan-Åke Larsson