A graphics library for fast image creation

Follow this link to the latest version of this document.

UPGRADING UNIX USERS: READ THIS FIRST! Modern versions of gd install by default to /usr/local/lib and /usr/local/include. If you already have an older version of gd in /usr/lib and /usr/include, you may wish to use:

./configure --prefix=/usr

To ensure that your new installation overwrites the old.

GIF support has been restored in gd 2.0.28. The well-known patents on LZW compression held by Unisys have expired in all countries. British Telecom and IBM may hold related patents but have never chosen to require royalties for GIF applications, to the best of my knowledge. I am not a lawyer and cannot give legal advice regarding this issue. PNG remains a superior format especially if lossless truecolor images are needed.

When building from soruce, gd 2.0.28 requires that the following libraries also be installed, in order to produce the related image formats. The win32 binary release (bgd) already contains the appropriate libraries. You may skip libraries associated with formats you do not use:

libpng (see the libpng home page), if you want PNG

zlib (see the info-zip home page), if you want PNG

jpeg-6b or later, if desired (see the Independent JPEG Group home page), if you want JPEG

If you want to use the TrueType font support, you must also install the FreeType 2.x library, including the header files. See the Freetype Home Page, or SourceForge. No, I cannot explain why that site is down on a particular day, and no, I can't send you a copy.

If you want to use the Xpm color bitmap loading support, you must also have the X Window System and the Xpm library installed (Xpm is often included in modern X distributions). Most of the time you won't need Xpm.

Please read the documentation and install the required libraries. Do not send email asking why png.h is not found. Do not send email asking why libgd.so is not found, either. See the requirements section for more information. Thank you!

Table of Contents

• Credits and license terms
• What's new in version "XYZ" of GD?
• What is gd?
• What if I want to use another programming language?
• What else do I need to use gd?
• How do I get gd?
• How do I build gd?
• gd basics: using gd in your program
• webpng: a useful example
• Function and type reference by category
• About the additional .gd image file format
• Please tell us you're using gd!
• How do I get support?
• Alphabetical quick index

Up to the Boutell.Com, Inc. Home Page

Credits and license terms

In order to resolve any possible confusion regarding the authorship of gd, the following copyright statement covers all of the authors who have required such a statement. If you are aware of any oversights in this copyright notice, please contact Thomas Boutell who will be pleased to correct them.

COPYRIGHT STATEMENT FOLLOWS THIS LINE

Portions copyright 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 by Cold Spring Harbor Laboratory. Funded under Grant P41-RR02188 by the National Institutes of Health.

Portions copyright 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 by Boutell.Com, Inc.

Portions relating to GD2 format copyright 1999, 2000, 2001, 2002, 2003, 2004 Philip Warner.

Portions relating to PNG copyright 1999, 2000, 2001, 2002, 2003, 2004 Greg Roelofs.

Portions relating to gdttf.c copyright 1999, 2000, 2001, 2002, 2003, 2004 John Ellson (ellson@graphviz.org).

Portions relating to gdft.c copyright 2001, 2002, 2003, 2004 John Ellson (ellson@graphviz.org).

Portions relating to JPEG and to color quantization copyright 2000, 2001, 2002, 2003, 2004, Doug Becker and copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 Thomas G. Lane. This software is based in part on the work of the Independent JPEG Group. See the file README-JPEG.TXT for more information.

Portions relating to GIF compression copyright 1989 by Jef Poskanzer and David Rowley, with modifications for thread safety by Thomas Boutell.

Portions relating to GIF decompression copyright 1990, 1991, 1993 by David Koblas, with modifications for thread safety by Thomas Boutell.

Portions relating to WBMP copyright 2000, 2001, 2002, 2003, 2004 Maurice Szmurlo and Johan Van den Brande.

Permission has been granted to copy, distribute and modify gd in any context without fee, including a commercial application, provided that this notice is present in user-accessible supporting documentation.

This does not affect your ownership of the derived work itself, and the intent is to assure proper credit for the authors of gd, not to interfere with your productive use of gd. If you have questions, ask. "Derived works" includes all programs that utilize the library. Credit must be given in user-accessible documentation.

This software is provided "AS IS." The copyright holders disclaim all warranties, either express or implied, including but not limited to implied warranties of merchantability and fitness for a particular purpose, with respect to this code and accompanying documentation.

Although their code does not appear in the current release, the authors also wish to thank Hutchison Avenue Software Corporation for their prior contributions.

END OF COPYRIGHT STATEMENT

gd is a graphics library. It allows your code to quickly draw images complete with lines, arcs, text, multiple colors, cut and paste from other images, and flood fills, and write out the result as a PNG or JPEG file. This is particularly useful in World Wide Web applications, where PNG and JPEG are two of the formats accepted for inline images by most browsers.

gd is not a paint program. If you are looking for a paint program, you are looking in the wrong place. If you are not a programmer, you are looking in the wrong place, unless you are installing a required library in order to run an application.

gd does not provide for every possible desirable graphics operation. It is not necessary or desirable for gd to become a kitchen-sink graphics package, but version 2.0 does include most frequently requested features, including both truecolor and palette images, resampling (smooth resizing of truecolor images) and so forth.

What if I want to use another programming language?

PHP

Perl

OCaml

Tcl

Pascal

REXX

Any Language

• fly, by Martin Gleeson

What's new in version 2.0.28?

• GIF support has been restored. See gdImageGif, gdImageGifCtx, gdImageGifPtr, gdImageCreateFromGif, gdImageCreateFromGifCtx, and gdImageCreateFromGifPtr. These functions are now thread-safe, similar to the PNG and JPEG manipulation functions.
• The new gdImageCreatePaletteFromTrueColor function is identical to gdImageTrueColorToPalette, except that it returns a new image rather than permanently modifying the original.

What's new in version 2.0.27?

• In gd 2.0.26, there was potential for out of bounds fills, and therefore crashes, in the horizontalLine function used by gdImageFilledPolygon. Fixed by John Ellson.
• The order of the points returned in the bounding rectangle by gdImageStringFT was incorrect in version 2.0.26. This has been corrected in version 2.0.27. Thanks to Riccardo Cohen for pointing this out, and to John Ellson for verifying and fixing it.

What's new in version 2.0.26?

The following enhancements and fixes:

• Drastically faster, less memory-intensive antialiased drawing, thanks to Pierre-Alain Joye. This code was imported from the PHP "fork" of gd. The API for antialiased drawing has not changed, however the implementation has been completely replaced. Antialiased line drawing does not support widths other than 1, however this did not work properly with the other implementation of antialiasing either. Support has been included for the "non-blending color" option introduced by the previous implementation of antialiased drawing.
• gdlib-config, which has been installed by make install for some time now, has gained a --features option. This option produces a space-separated list of optional features with which the gd library was compiled. Typical usage looks like this:

  % gdlib-config --features
  GD_XPM GD_JPEG GD_FREETYPE GD_PNG GD_GIF
  

  Other configure scripts can conveniently define preprocessor symbols based on this list in order to conditionally compile code. For instance, if GD_PNG is not reported by --features, then gdImagePng is not included in the library.

  Thanks to Lars Hecking and Lincoln Stein for their advice on implementing this feature. Any blame for the actual implementation is entirely due to me (TBB).

• Fixes to the behavior of the bounding rectangle returned by gdImageStringFT and relatives when the string is rotated. See fontwheeltest.c. Thanks to John Ellson.
• Previously, gdImageStringFT and friends accepted either a full path to a font file, or the name of a font with no extension, in which case the GDFONTPATH environment variable and then the compiled-in DEFAULT_FONTPATH was searched. In addition, a font filename with an extension but no full path can now be automatically searched for in the same fashion. Thanks to John Ellson.
• Fixes to freetype antialiased text against a transparent background. See testtr.c. Thanks to John Ellson.
• Support for named entities like & and hex-coded entities such as 水 in text strings passed to gdImageStringFT and relatives, adding to the previous support for decimal-coded entities like Å. These were extracted from entities.html (from the W3C) via the script entities.tcl, which is included for the curious and those with other entities they need support for. Thanks to John Ellson.
• Optimization: gdImageSetPixel no longer calls gdImageAlphaBlend when either the source or the destination pixel is 100% transparent. Thanks to John Ellson.
• Optimization: gdImageLine is potentially faster now in the most common cases. Thanks to John Ellson.
• Documentation of the entities feature of gdImageStringFT.
• autoconf/configure fixes. Thanks to many who pointed out an oversight in handling libpng flags.

What's new in version 2.0.25?

Owing to an oversight while making changes to better accommodate the use of gd as a DLL, the extern qualifier was dropped from the declarations of font pointers in 2.0.24. This has been corrected. Thanks to Richard ("OpenMacNews").

What's new in version 2.0.24?

Windows DLL now uses __stdcall calling convention. Existing applications will require a recompile, using the new version of gd.h, in order to use this version of the DLL. However, Visual BASIC and other non-C programmers will now be able to use the DLL, which is an enormous benefit and justifies the one-time inconvenience to existing DLL users.

The elaborate #ifdef test for older versions of Freetype without FT_ENCODING_MS_SYMBOL was needed in a second place also. Thanks to David R. Morrison.

An off-by-one error in gdImageToPalette caused transparency to be applied to the wrong pixels. Thanks to "Super Pikeman."

What's new in version 2.0.23?

Output dpi specification option added to the gdFTStringExtra structure, thanks to Mark Shackelford. See gdImageStringFTEx.

What's new in version 2.0.22?

• Win32 DLL users: working with pointers exported by DLLs is difficult and causes unexpected results. gd 2.0.22 exports new functions for retrieving the basic gd fonts: gdFontGetTiny(), gdFontGetSmall(), gdFontGetMediumBold(), gdFontGetLarge(), and gdFontGetHuge(). You may safely assign the return values from these functions to a local gdFontPtr. Direct use of gdFontLarge, etc. is strongly deprecated for users of bgd.dll; use these new functions instead.
• Basic support for loading CMYK-colorspace JPEG images. They are of course converted to RGB which is a lossy process, however the results do look quite good and are certainly fine for thumbnails and web previews of DTP work.
• "make" no longer fails on circletexttest if PNG support is missing.
• Small performance improvements to gdImageCopyResampled; larger improvements are forthcoming.

What's new in version 2.0.21?

• Version 2.0.21 adds a gdImageCreateFrom*Ptr family of functions which make it convenient to load an image in any GD-supported format directly from memory.
• The new gdNewDynamicCtxEx function was added to support the easy implementation of the above functions and to correct a design problem which made life unpleasant for those passing in memory not originally allocated by gd to the gdNewDynamicCtx function by provoding a way to specify that gd should never free or reallocate a particular block of memory. The gdNewDynamicCtx function and its relatives, although still exported for ABI compatibility, are now deprecated except for internal use, in favor of gdImageCreateFromPngPtr and its relatives.
• Version 2.0.21 includes a new patch from Ethan A. Merritt to correct a bug in the conditional compilation of support for symbol fonts in gdft.c. Symbol fonts should now work correctly. Thanks to Mr. Merritt.
• Version 2.0.20 restores the gdFreeFontCache function, an undocumented function added in an earlier release which now simply calls gdFontCacheShutdown for backwards compatibility. This repairs build problems when compiling PHP against the latest gd.
• Documentation improvements.

What's new in version 2.0.20?

• Version 2.0.20 restores the gdFreeFontCache function, an undocumented function added in an earlier release which now simply calls gdFontCacheShutdown for backwards compatibility. This repairs build problems when compiling PHP against the latest gd.

What's new in version 2.0.19?

• Version 2.0.19 restored extern declarations for the gd font pointers inadvertently removed in 2.0.18.

What's new in version 2.0.18?

• A Win32 binary distribution of "bgd.dll," built with mingw32 and tested with win32 versions of the demo programs as console applications, is now available.
• Semicolon rather than space used as the default separator of alternative font file paths in gdImageStringFT, for better compatibility with Windows and other environments where spaces are common in paths.
• The circletexttest demo no longer fails to compile when JPEG support happens to be absent.

What's new in version 2.0.17?

Minor compilation and packaging problems with 2.0.16 were corrected. If 2.0.16 compiled without errors for you, then you don't need to upgrade to 2.0.17.

What's new in version 2.0.16?

• Thread safety for freetype text output. Background: all gd functions were already thread safe, as long as only one thread manipulates each image -- except for gdImageStringFT and gdImageStringFTEx. This is because of a shared freetype font cache. Sharing the cache between images is worthwhile, so "configure" now detects pthreads and uses it to wrap freetype text output in a critical section if available. There is also critical section support under WIN32. Those who wish to be strictly thread-safe should call the new function gdFontCacheSetup before allowing any thread to use freetype text calls. Otherwise this function is automatically invoked on the first use of freetype, with a very small but real chance of a race condition.
• gdImageSquareToCircle performs a "polar coordinate transform," returning a new image in which the X axis of the original has been remapped to theta (angle) and the Y axis of the original has been remapped to rho (distance from center).
• gdImageStringFTCircle wraps text in a circle around a specified center point. This function takes advantage of gdImageSquareToCircle. The result is very smooth, although it takes some time to compute. Thanks to Steve Bassi for sponsoring this work.
• gdImageSharpen, contributed by Paul Troughton. Thank you.
• Christophe Thomas corrected gdft.c to include freetype header files in the way that is now mandatory in freetype 2.1.6 and above.
• Gustavo Scotti fixed a memory leak in gdft.c.
• Clipping rectangle respected in freetype text output. Thanks to Matt McNabb.
• Paul den Dulk found a degenerate case that crashes gdImageToPalette. Fixed.
• Optimization by Ilia Chipitsine to avoid wasting time with offscreen scanlines during polygon rasterization.
• Optimized PNG saving by Phong Tran. Speeds up saves a little bit.
• Bug in gdImageCopyResized fixed by Mao Morimoto.

What's new in version 2.0.15?

• gd.c in 2.0.14 contained an instance of declaring variables after the first line of executable code appears. This is of course not allowed by ANSI C, although many compilers accept it. My apologies. Thanks to Jeff Vendetti for reporting this quickly.

What's new in version 2.0.14?

• 2.0.13 was available for mere minutes due to a typo in the new bounds-checking code for antialiased line drawing. Fixed.
• Not all platforms -- notably msys/mingw -- have an ssize_t type. We now call an int an int in gd_jpeg.c, with good results. (Note: ssize_t is signed, unlike size_t, and it needs to be here.)

What's new in version 2.0.13?

• The main() function of one of the test programs was accidentally included in the gd shared library, causing problems on some platforms. This has been corrected. Thanks to many people who pointed this out.
• The antialiased drawing functions now have proper bounds checking. Thanks to Arne Jorgensen.
• A void function returned a value in gd_png.c, causing warnings and, on some platforms, compilation errors but no reported runtime problems. Thanks to Kevin Smith, among others.
• Autohinting was being forced ON for freetype text output. This is apparently meant only for testing freetype and does not look as good as the default behavior (FT_LOAD_DEFAULT). Thanks to Bob Ostermann.
• penf.x is properly reset when newlines are encountered in freetype text output. Thanks to Christopher J. Grayce.

What's new in version 2.0.12?

• Small but numerous code cleanups by Dr. Martin Zinser.
• gdImageSetClip and gdImageGetClip have been added. All drawing routines now stay within the specified clipping rectangle. Note that the gdImageBoundsSafe function now returns true only if the specified location is within the clipping rectangle. Of course, the default clipping area is the entire image. The behavior of existing gd applications does not change.
• Support for fast drawing of antialiased lines and polygons, by Bright Fulton and Frank Faubert. To learn more about this feature, read about the gdImageSetAntiAliased function, which is used to set the foreground color for antialiasing, as well as the gdAntiAliased constant, which is passed to line- and polygon-drawing functions in place of a color. This code does not currently support an alpha channel component in the specified foreground color, or in the existing background image, but does perform alpha blending against an opaque background. Also see the gdImageSetAntiAliasedDontBlend function, which allows the specification of a special background color that should never be blended with the foreground.
• Fixes to color mapping in gdImageCopyMergeGray. Thanks to Philip Warner.
• gdImageStringFTEx now supports explicit specification of the desired character mapping. This is useful when a font offers more than one of Unicode, Shift_JIS, and Big5.
• The PNG compression level can now be specified when writing PNG images. See the new gdImagePngEx, gdImagePngEx, gdImagePngCtxEx, and gdImagePngPtrEx functions.
• The annotate utility builds without error in the absence of freetype, although of course it is not useful without freetype.
• Thorben Kundinger fixed a bug relating to the use of palette-based images as brushes when drawing on truecolor images.
• Michael Schwartz corrected a problem with his code for drawing thick lines.
• Prior to 2.0.12, any alpha channel component in the destination image was ignored when drawing with alpha blending in effect (see gdImageAlphaBlending). 2.0.12 correctly preserves an appropriate proportion of the alpha component of the destination, just as it preserves an appropriate proportion of the red, green and blue components, depending on the opacity of the foreground. Thanks to Frank Warmerdam for pointing out the issue.
• Memory leaks on failed attempts to load fonts in gdImageStringFTEx were corrected. Thanks to Frank Faubert.
• The impact of kerning is now correctly included in the calculation of the bounding box returned by the freetype text routines. This issue was pointed out by several individuals.
• Color problems with the gd2 file format routines were fixed by Steven Brown. These problems were due to the incorrect use of a signed integer.
• Version 2.0.12 supports the gd file format correctly for truecolor images. Truecolor gd files created with earlier releases in the 2.0 series must be written again. The gd file format is used to quickly load an entire uncompressed image, typically an existing background to which additional material will be added; it is not a general purpose file format. More advanced capabilities are also available via the gd2 format. Thanks to Andreas Pfaller for reporting the problem.
• Signed vs. unsigned problem caused misbehavior when attempting to load a bad JPEG image. Thanks to Geert Jansen.
• Existing truecolor PNG images with simple single-color transparency are now loaded properly, thanks to Slaven Rezic.
• The gdImageTrueColorToPalette function no longer attempts to preserve an alpha channel in the original. My attempt to do so resulted in significantly inferior output even if no alpha channel was present in the original. Thanks to Barend Gehrels for submitting a new adaptation of Tom Lane's jquant2.c which does a very high-quality job of palette conversion. Thanks also to Steven Brown, who submitted patches allowing a single 100% transparent color in the original truecolor image to be preserved. In practice, more complex alpha channels in palettes are ill-supported and difficult to allocate skillfully.

What's new in version 2.0.11?

• Support for the "gd2" file format, which allows fast loading of all or only part of an existing image, has been properly debugged for use with truecolor images. (Palette images already worked properly, except for a bug when loading from a regular file with gdImageCreateFromGd2Part, which has also been fixed.) .gd2 files can be either compressed or uncompressed, and they allow useful tricks such as fast loading of a 500x500 pixel region of a 6000x3000 pixel image, without uncompressing all of the image. .gd2 is NOT a general purpose file format and should only be used where quick loading of a background image or subset of a larger image is required. For more information, see gdImageGd2, gdImageCreateFromGd2, and gdImageCreateFromGd2Part.
• The gd2topng utility has been extended to support extraction of only part of an image from a .gd2 file. This is both a demonstration and a practical tool.
• Additional configure improvements by Lars Hecking.

What's new in version 2.0.10?

• gdImageLine now clips to the edges of the image before drawing lines, which greatly improves performance when many lines extend outside or are entirely outside the actual image. Thanks to Nick Atty for this code.
• gdImageBoundsSafe is replaced with a macro when called internally; this improves the performance of gdImageSetPixel and gdImageGetPixel a little bit, and therefore everything else as well. Thanks to Nicky Atty for the idea.
• Transparent indexes are handled properly with non-truecolor source images in gdImageCopy. Thanks to Frank Warmerdam.
• floor() replaced with a cast to long in gdImageCopyResampled, for a roughly 35% performance boost. Thanks to John Buckman.
• gdft.c builds correctly on WIN32 without patches.
• Much faster gdImageCreateFromJpeg routines, thanks to Christian Aberger for more efficient pointer arithmetic.
• gdtestft correctly builds without PNG tests if PNG support is not present. Thanks to Gabriele Verzeletti.

What's new in version 2.0.9?

• Version 2.0.9 contains a fix to gdImageCopyResized which allows correct results when copying a palette-based image with a single transparent index into a truecolor image. Thanks to Thorben Kundinger.
• More configure fixes from Lars Hecking. Thanks, Lars.

What's new in version 2.0.8?

• Version 2.0.8 contains additional fixes to the 'configure' script, allowing a clean out-of-the-box build on more systems.
• Version 2.0.8 adds the new gdImageCopyRotated function, which can rotate any rectangular image region by an arbitrary number of degrees.

What's new in version 2.0.7?

Version 2.0.7 corrects a problem which caused 'configure' to complain that the directory NONE was not found, in various places, causing the configuration process to stop. There are no code changes.

What's new in version 2.0.6?

• Fixed a compilation problem with gdft.c. A declaration appeared after executable code, and gcc let it slide by, so it made it out the door. My apologies!
• As penance, I have seen to it that the entire library now compiles cleanly with the -Wall, -ansi and -pedantic options enabled.

What's new in version 2.0.5?

• libgd 2.0.5 INSTALLS IN /usr/local/lib BY DEFAULT. IF YOU WANT IT TO INSTALL IN /usr/lib, YOU MUST SPECIFY THIS at configure time using this syntax:

  ./configure --prefix=/usr

• gd now uses GNU autoconf. This means that the provided configure script should be compatible with all standard GNU configure options and will figure out the correct settings for a much wider range of operating systems. Many, many thanks to Lars Hecking for taking care of this.
• The gdImageStringFTEx function is now included, thanks to Wez Furlong. My apologies to Wez for the unreasonable amount of time this patch has sat in my queue.
• Additional fixes from Wez Furlong.
• Arithmetic cleanup by Doug Claar.
• Corrections to loading and saving of alpha channel information in PNG files, by Andrew Hull.
• gdImageTrueColorToPalette does not contain unneeded test code.
• gdImageCopyResized works properly again when copying from a non-truecolor source.

What's new in version 2.0.4?

• Various test programs now compile in the absence of PNG support
• gdIOCtx correctly calls gdFree rather than free
• Various cleanups to pass -Wall without warnings
• Support for Adobe-style Type 1 fonts (.pfa and .pfb files) via freetype
• gdImageColorResolve and gdImageColorResolveAlpha will not attempt to resolve a color request to the transparent color index (for palette-based images)
• Improved font search path support
• Antialiased freetype text on palette images works properly when more than one image is created in a single program lifetime with different color indexes
• Better threshold for two-color "mono" images
• Memory leak fixes
• Text rotation fix
• More extensive default font path
• fontwheeltest and fontsizetest test programs for freetype

• configure now correctly detects and provides support for the Xpm library and its dependencies (Len Makin)

• The configure script has been extensively modified to work properly in tests with both Solaris and Linux. Other platforms should also work based on feedback received and integrated to date.
• The --prefix option to configure works properly.
• The annotate utility has been added. This is a very handy tool for adding freetype text to existing JPEGs. After make install, type annotate -h for more information. Thanks to Joel Dubiner.

What's new in version 2.0.2?

• A "configure" script has been added. After wrestling with GNU autoconf for a while, I got tired of trying to make it detect libraries but accept their absence gracefully, and so on. Instead, I wrote a short Perl script which does the job and builds a reasonable Makefile. Those who find it doesn't detect their system's needs properly are welcome to contribute patches or the necessary commands.
• Antialiased freetype text output now works properly in both truecolor and non-truecolor contexts! Hurrah! On a truecolor image it is possible, for instance, to draw antialiased text on an arbitrarily complex background with 50% alpha blending (transparency), and get the expected pretty results. Thanks to Joel Dubiner for his support of this work.
• By default, alpha blending is now done within the library. Also, by default, alpha channel is not saved with PNG images. This means that programmers who try loading a JPEG, scribbling some pretty antialiased text on it, and saving the JPEG again will now get the results they expected. It also means that, by default, users will not run afoul of the fact that many web browsers don't properly support full PNG alpha channel.
• Various submitted bug fixes have been incorporated.
• Various other submitted changes have not been incorporated. Sorry. The interval between 2.0.1 and 2.0.2 was simply too long, and changes accumulated which were not mutually compatible. I'll do better in the future, especially with bug fixes.

What's new in version 2.0.1?

• Workaround for a bug in gcc, apparently found in gcc 2.7.2 and up. I reproduced and fixed it while using gcc 2.9.5.2. The bug occurred only when the -g option was in use. This problem caused gcc to spew internal error messages unrelated to the correctness of the code in gd_gd2.c. Howard Jones was first to report it.
• gdImageFilledEllipse documented and altered; no longer requires a superfluous style argument. Thanks to Francis James Franklin.
• The Makefile now offers the correct syntax for optionally creating a static library. Thanks to Jean-Lous Regez, among others.
• A nested comment, an attempt to return the value of a void function, and a potentially significant error in gdImageCopyResampled were fixed thanks to Joseph Shirley.
• A bug preventing proper truecolor text rendering was fixed, thanks to Jason Gallagher.
• gdImageStringFT (FreeType) should now work better against a transparent or semitransparent background, and should act in a manner consistent with the most recent gdImageAlphaBlending setting. Antialiasing is now done via the alpha channel mechanism if the image is a truecolor image.
• Bugs in the output of gdImageArc and gdImageFilledArc were reported by Bruce Verderaime. A simple and correct but inefficient implementation has been substituted until fixes are contributed for the faster code, which is in gd_arc_f_buggy.c along with the test program that reproduces the bug(s).
• gdImageFilledArc now offers additional style options, which can be combined to produce various effects.
• Masahito Yamaga (ma@yama-ga.com) sent a patch to improve support for Japanese output via gdImageStringFT. He also added a new readme.jpn file.
• Zillions of documentation fixes.

What's new in version 2.0?

• Support for truecolor images! Version 2.0 can load truecolor PNGs with no loss of color information, and almost no loss of alpha channel information. Version 2.0 can also load truecolor JPEGs with as little loss as possible; however, bear in mind that JPEG is a lossy format, so repeated load/save cycles always reduce image quality. This is not a bug. To create a truecolor image from scratch, call the new gdImageCreateTrueColor function. The gdImageCreate function is still available to create palette images, and may also be referred to as gdImageCreatePalette.
• Support for alpha channels! In addition to 24 bits of color information for each pixel (eight bits of red, green, and blue respectively), version 2.0 supports 7 bits of "alpha channel" information. This is used to determine exactly how transparent the pixel should be. There is also support for a full 7 bits of transparency for each individual palette index in a palette-based image. Please note that, as of this writing, only Macintosh Internet Explorer 5.x and Mozilla/Netscape 6.x display partial transparency properly.
• The new gdImageAlphaBlending function allows for two different modes of drawing. In blending mode, the alpha channel component of the color supplied to all drawing functions, such as gdImageSetPixel, determines how much of the underlying color should be allowed to shine through. The resulting image is not transparent. In non-blending mode, drawing color is copied literally with the alpha channel information, resulting in a transparent image. Blending mode is not available when drawing on palette images.
• The gdImageCopyResampled function provides "smooth" copying from a large image to a smaller one, using a weighted average of the pixels of the source area rather than selecting one representative pixel. This function is identical to gdImageCopyResized when the destination image is a palette image.
• The gdImageTrueColorToPalette function converts a truecolor image to a palette image. The code for this function was originally drawn from the Independent JPEG Group library code, which is excellent. The code has been modified to preserve as much alpha channel information as possible in the resulting palette, in addition to preserving colors as well as possible. This does not work as well as might be hoped. It is usually best to simply produce a truecolor output image instead, which guarantees the highest output quality.
• A very high degree of backwards compatibility with existing gd 1.x code has been maintained, at both the source code and binary level. Code which directly accesses the pixels array will fail only if it encounters an existing truecolor image, which may happen if the code attempts to open and modify an existing JPEG or truecolor PNG. Such code should be modified to check the trueColor flag of the gdImage structure, and refer to the tpixels array instead when it is set.
• gd is now compiled and installed as a shared library. However, gd still does not use autoconf, because I (TBB) have very limited patience with autoconf. These days, most Unix systems provide a fairly POSIX-standard environment, and the provided Makefile is likely to work well if users read it and follow the instructions at the top.
• Support for line thickness was added by Michael Schwartz. My apologies to him for sitting on his patches for so long. See the new gdImageSetThickness function, which affects all standard gd functions that draw lines and curves. In addition, Michael added a convenient gdImageEllipse function.
• The new gdImageFilledArc function provides a straightforward way to draw filled arcs. Also, gdImageFilledEllipse is a convenient way to fill an ellipse without specifying starting and ending angles. Thanks go out to F J Franklin.
• To put an end to the confusion, TrueType 1.x support has been removed in favor of TrueType 2.x support. The old gdImageStringTTF function simply invokes gdImageStringFT.
• The specialized .gd and .gd2 file formats have been upgraded to support truecolor. New images written by the versions of these functions found in 2.0 will be rejected, with varying degrees of grace, by older versions of gd. THIS AFFECTS THE .GD and .GD2 FORMATS ONLY. IF YOU ARE CONFUSED BY THIS PARAGRAPH, IT PROBABLY DOESN'T APPLY TO ANYTHING YOU WILL EVER ENCOUNTER. Since these file formats are absolutely, positively *not* designed for distributing images, just for preprocessing them, this should not be a big problem. gd 2.0 should read old .gd and .gd2 files correctly.

What's new in version 1.8.4?

• Add support for FreeType2 (John Ellson ellson@graphviz.org)
• Add support for finding in fonts in a builtin DEFAULT_FONTPATH, or in a path from the GDFONTPATH environment variable.
• remove some unused symbols to reduce compiler warnings
• bugfix in size comparisons in gdImageCompare
• REXX now mentioned
• All memory allocation functions are now wrapped within the library; gdFree is exported and recommended for freeing memory returned by the gdImage(Something)Ptr family of functions.

What's new in version 1.8.3?

• WBMP output memory leak fixed
• #include <gd.h> corrected to #include "gd.h" in gd_wbmp.c
• Documented the fact that the source and output images shouldn't match in the WBMP test except for black and white source images

What's new in version 1.8.2?

• WBMP support debugged and improved by Johann Van den Brande
• WBMP tests added to gdtest.c by Thomas Boutell
• Use of platform-dependent 'install' command removed by Thomas Boutell
• Comments added to Makefile warning users to juggle the order of the libraries if the linker complains; is there any portable way to do this automatically, short of using autoconf?
• Documentation of gdImageCreateFromXpm corrected
• Updated links to fast-moving, always dodging libpng and zlib websites

What's new in version 1.8.1?

• Optional components no longer built by default (following the documentation)
• JPEG code no longer requires inappropriate header files
• Win32 patches from Joe Gregorio
• 16-bit font support for bdftogd, from Honza Pazdziora

What's new in version 1.8?

• Support for JPEG output, courtesy of Doug Becker
• A link to Michael Bradbery's Pascal wrapper
• Support for WBMP output, courtesy of Maurice Szmurlo
• gdImageColorClosestHWB function based on hue, whiteness, blackness, superior to the regular gdImageColorClosest function, courtesy of Philip Warner
• License clarification: yes, you can modify gd

Additional JPEG Information

What's new in version 1.7.3?

What's new in version 1.7.2?

Documentation fixes. Thanks to Dohn Arms.

Makefile fixes to permit linking with all libraries required on platforms with order- dependent linkers.

What's new in version 1.7.1?

What's new in version 1.7?

• Japanese language support for the TrueType functions. Thanks to Masahito Yamaga.
• autoconf and configure have been removed, in favor of a carefully designed Makefile which produces and properly installs the library and the binaries. System-dependent variables are at the top of the Makefile for easy modification. I'm sorry, folks, but autoconf generated many, many confused email messages from people who didn't have things where autoconf expected to find them. I am not an autoconf/automake wizard, and gd is a simple, very compact library which does not need to be a shared library. I did make many improvements over the old gd 1.3 Makefile, which were directly inspired by the autoconf version found in the 1.6 series (thanks to John Ellson).
• Completely ANSI C compliant, according to the -pedantic-errors flag of gcc. Several pieces of not-quite-ANSI-C code were causing problems for those with non-gcc compilers.
• gdttf.c patched to allow the use of Windows symbol fonts, when present (thanks to Joseph Peppin).
• extern "C" wrappers added to gd.h and the font header files for the convenience of C++ programmers. bdftogd was also modified to automatically insert these wrappers into future font header files. Thanks to John Lindal.
• Compiles correctly on platforms that don't define SEEK_SET. Thanks to Robert Bonomi.
• Loads Xpm images via the gdImageCreateFromXpm function, if the Xpm library is available. Thanks to Caolan McNamara.

What's new in version 1.6.3?

What's new in version 1.6.2?

-lgd -lpng -lz -ljpeg -lfreetype -lm

/* Bring in gd library functions */
#include "gd.h"

/* Bring in standard I/O so we can output the PNG to a file */
#include <stdio.h>

int main() {
  /* Declare the image */
  gdImagePtr im;
  /* Declare output files */
  FILE *pngout, *jpegout;
  /* Declare color indexes */
  int black;
  int white;

  /* Allocate the image: 64 pixels across by 64 pixels tall */
  im = gdImageCreate(64, 64);

  /* Allocate the color black (red, green and blue all minimum).
    Since this is the first color in a new image, it will
    be the background color. */
  black = gdImageColorAllocate(im, 0, 0, 0);  

  /* Allocate the color white (red, green and blue all maximum). */
  white = gdImageColorAllocate(im, 255, 255, 255);  
  
  /* Draw a line from the upper left to the lower right,
    using white color index. */
  gdImageLine(im, 0, 0, 63, 63, white);  

  /* Open a file for writing. "wb" means "write binary", important
    under MSDOS, harmless under Unix. */
  pngout = fopen("test.png", "wb");

  /* Do the same for a JPEG-format file. */
  jpegout = fopen("test.jpg", "wb");

  /* Output the image to the disk file in PNG format. */
  gdImagePng(im, pngout);

  /* Output the same image in JPEG format, using the default
    JPEG quality setting. */
  gdImageJpeg(im, jpegout, -1);

  /* Close the files. */
  fclose(pngout);
  fclose(jpegout);

  /* Destroy the image in memory. */
  gdImageDestroy(im);
}

typedef struct {
        int (*source) (void *context, char *buffer, int len);
        void *context;
} gdSource, *gdSourcePtr;

typedef struct {
        int (*sink) (void *context, char *buffer, int len);
        void *context;
} gdSink, *gdSinkPtr;