GIMP version history
GIMP originally stood for General Image Manipulation Program.  Its creators, Spencer Kimball and Peter Mattis, began developing GIMP as a semester-long project at the University of California, Berkeley in 1995. The name was changed to the GNU Image Manipulation Program in 1997, after Kimball and Mattis had graduated, when it became an official part of the GNU Project.
|Major version||Minor versions||Release date and significant changes|
|0.x||0.54–0.99.31||February 15, 1996: ?|
|1.0.x||1.0.0–1.0.3||June 5, 1998: ?|
|1.2.x||1.2.0–1.2.5||December 25, 2000: Improvements to the user interface, bug fixes.|
|2.0.x||2.0.0–2.0.6||March 23, 2004: Many new tool options, GIMP now using GTK+ 2.x graphical toolkit. Tabs and docks system introduced. Script-fu scripting support improved greatly. Allows text to be re-edited. CMYK color support.|
|2.2.x||2.2.0–2.2.17||December 19, 2004: plugin support, keyboard shortcut editor, previews for transform tools. New GIMP hardware controllers support. Drag/drop and copy/paste from GIMP to other applications improved.|
|2.4.x||2.4.0-2.4.7||October 24, 2007: Color management support, scalable brushes, new and rewritten selection tools and many user interface changes including a new icon theme. Increased file format support. Full screen editing, and new crop tools. Improved printing quality. Improved interface for external device input.|
|2.6.x||2.6.0||October 1, 2008: GEGL, and first iteration of UI redesign|
|2.6.1 - 2.6.5||Bugfixes, updated translations.|
|2.6.6||March 17, 2009: Bugfixes, updated translations.|
|2.8.x||2.8.0||May 3, 2012: Single-window mode, exporting, layer groups, tool improvements, and many more updates.|
GIMP 0.54 was released in January 1996.  It required X11 displays, an X-server that supported the X shared memory extension and Motif 1.2 widgets. It supported 8, 15, 16 and 24-bit color depths, dithering for 8-bit displays and could view images as RGB color, grayscale or indexed color. It could simultaneously edit multiple images, zoom and pan in real-time, and supported GIF, JPEG, PNG, TIFF and XPM images.
Even at this early stage of development GIMP functionality was extensive. It could select regions using rectangle, ellipse, free, fuzzy, bezier, and intelligent selection tools, and rotate, scale, shear and flip images. It had bucket, brush and airbrush painting tools, and could clone, convolve, and blend images. It had text tools, effects filters (such as blur and edge detect), and channel and color operations (such as add, composite, decompose). The plugin system allowed for addition of new file formats and new effect filters. It supported multiple undo and redo operations.
It ran on Linux 1.2.13, Solaris 2.4, HP-UX 9.05, and SGI IRIX operating systems. It was rapidly adopted by users,  who created tutorials, displayed artwork and shared techniques. An early success for GIMP was the Linux penguin Tux, as drawn by Larry Ewing using Gimp 0.54. By July 5, 1996 the volume of messages posted to the mailing list had risen and the mailing list was split into two lists, gimp-developer and gimp-user. Currently, user questions are directed to the gimpnet IRC channel.
GIMP 0.60 was released on June 6, 1997 using the GNU General Public License.  According to the release notes, Peter Mattis was working for Hewlett-Packard and Spencer Kimball was working as a Java programmer. 
GIMP 0.60 no longer depended on the Motif toolkit. Improvements had been made to the painting tools, airbrush, channel operations, palettes, blend tool modes, image panning and transformation tools. The editing work flow was improved by enabling rulers, cutting and pasting between all image types, cloning between all image types and ongoing development of a layers dialog.
New tools included new brushes (and a new brush file format), grayscale and RGB transparency,"Bucket fill" patterns and a pattern selection dialog, integrated paint modes, border, feather and color selectors, a pencil and eraser paint tool, gamma adjustments and a limited layer move tool.
The new widgets were managed by Peter Mattis and were called GTK for GIMP toolkit and GDK for GIMP drawing kit.
Sometime in 1998, after a few humorous suggestions of a gimp compile on Microsoft Windows, Tor Lilqvist began the effort of the initial port of GIMP for windows. At the time it was considered a code fork. It would later be merged into the main development tree. Support was, and continues to be, offered through a yahoogroups email list.
The biggest change in the GIMP 0.99 release was in the GIMP toolkit (GTK). GTK was redesigned to be object oriented and renamed from GTK to GTK+. The pace of development slowed when Spencer Kimball and Peter Mattis found employment.
GIMP 1.0.0 was released on June 2, 1998 GIMP and GTK+ split into separate projects during the GIMP 1.0 release. GIMP 1.0 included a new tile based memory management system which enabled editing of larger images and a change in the plug-in API (Application programming interface) allowed scripts to be safely called from other scripts and to be self documenting. GIMP 1.0 also introduced a native file format (xcf) with support for layers, guides and selections (active channels).
An official website was constructed for GIMP during the 1.0 series, designed by Adrian Likins and Jens Lautenbacher, now found at classic.gimp.org which provided introductory tutorials and additional resources. On April 13, 1997, GIMP News was started by Zach Beane, a site that announced plug-ins, tutorials and articles written about GIMP. May 1997, Seth Burgess started GIMP Bugs, the first 'electronic bug list'.
Marc Lehmann developed a perl programming plug-in.    Web interfaces were possible with the GIMP 1.0 series, and GIMP Net-fu  can still be used for online graphics generation. 
The GIMP 1.1 series focused on fixing bugs and improving the port to Windows. No official release occurred during this series. Following this the odd numbered series (e.g. 1.1) of GIMP releases were considered unstable development releases and even numbered releases (e.g. 1.2) were considered stable releases. By this time, GTK+ had become a significant project and many of GIMP's original developers turned to GTK+ development. These included Owen Taylor (author of GIMP ifsCompose),  Federico Mena, Tim Janik,  Shawn Amundson and others. GNOME also attracted GIMP developers. The primary GIMP developers during this period were Manish Singh, Michael Natterer  Sven Neumann and Tor Lillqvist who primarily fixed issues so that GIMP could run on Win32. 
GIMP 1.2.0 was released on December 25, 2000. GIMP 1.2 had a new development team of Manish Singh, Sven Neumann and Mitch Natterer and others. GIMP 1.2 offered internationalization options, improved installation dialogs, many bug fixes (in GIMP and GTK+), overhauled plug-ins, reduced memory leaks and reorganized menus.  New plug-ins included GIMPressionist and Sphere Designer by Vidar Madsen;  Image Map by Maurits Rijk;  GFlare by Eiichi Takamori; Warp by John P. Beale, Stephen Robert Norris and Federico Mena Quintero; and Sample Colorize and Curve Bend by Wolfgang Hofer. New tools included a new path tool, a new airbrush tool, a resizable toolbox, enhanced pressure support, a measure tool, dodge, burn and smudge tools. New functionality included image pipes, jpeg save preview, a new image navigation window, scaled brush previews, selection to path, drag'n'drop, quickmask, a help browser, tear-off menus and the waterselect plug-in was integrated into the color-selector.
The 1.2 series was the final GIMP 1 series.
GIMP 2.0.0 was released on March 23, 2004. The biggest visible change was the transition to the GTK+ 2.x toolkit.
Among the major changes in GIMP 2.2 are:
- Previews for transform tools
- Improved drag-and-drop support
- A new script interpreter, Tiny-fu, which was supposed to eventually replace Script-fu (never did).
- New plugins: neon, cartoon, photocopy, softglow, dog, retinex, glob.
Major revisions in interface and tools were made available with the GIMP 2.4.0 release on October 24, 2007. Rewritten selection tools, use of the Tango style guidelines for a polished UI on all platforms, a foreground selection tool, and support for the ABR brush filetype along with the ability to resize brushes were some of the many updates.
More major revisions in interface and tools were made available with the 2.6.0 release on October 1, 2008. There were large changes in the UI, free select tool and brush tools, and lesser changes in the code base. Also, partial tool level integration of GEGL was enacted that is supposed to lead to higher color depths as well as non-destructive editing in future versions.  Starting from the first bugfix version, GIMP 2.6.1, the "The Utility Window Hint", that enforced MDI behavior on Microsoft Windows, as opposed to only being supported in GNOME.
2.8 was released on May 3, 2012 with several revisions to the user interface including a redesigned save/export menu that aims to reinforce the idea information is lost when exporting. The text tool was also redesigned so that a user edits text on canvas instead of in a separate dialog window, this was one of the Google Summer of Code (GSoC) projects from 2006.
2.8 also features layer groups, simple math in size entry fields, JPEG2000 support, PDF export, a webpage screenshot utility, and a single-window mode.
GEGL has also received its first stable release (0.1), where the Application Programming Interface is considered mostly stable; GEGL has continued to be integrated into GIMP, now handling layer projection, this is a major step forward into full integration of GEGL that will allow GIMP to have better non-destructive work-flows in future releases.
- Spencer Kimball & Peter Mattis (1996-02-11). "Readme" (txt). Retrieved 2008-03-23.
- GIMP - Prehistory - Before GIMP 0.54
- GIMP - Documentation
- Seth Burgess. "A Brief History of GIMP". Retrieved 2008-03-24.
- Seth Burgess. "A Brief History of GIMP". Retrieved 2008-03-24.[dead link]
- Zach Beane (2001-12-24). "Tips, Tricks, and other Stuff". Retrieved 2008-03-24.
- Tuomas Kuosmanen. "Gimp stuff". Retrieved 2008-03-24.
- Larry Ewing (1998-03-09). "Penguin Tutorial". Retrieved 2008-03-24.
- Federico Mena-Quintero (1997-10-23). "The GIMP's color gradient editor". Everyone loves The GIMP. Archived from the original on 2008-03-01. Retrieved 2008-03-24.
- Richard Stallman (1989-02-01). "GNU General Public License". Free Software Foundation. Retrieved 2008-03-23. "Because the program is licensed free of charge, there is no warranty for the program, to the extent permitted by applicable law."
- Spencer Kimball & Peter Mattis (1996-07-17). "Relnotes" (txt). Retrieved 2008-03-24.
- "Readme" (txt). 1996-07-17. Retrieved 2008-03-24.
- Adrian Likins and Jens Lautenbacher. "classic.gimp.org". Retrieved 2008-03-24.
- Marc Lehmann. "Gimp". Retrieved 2008-03-04.
- Seth Burgess (2002-06-05). "Seth's Perl-Fu". Retrieved 2008-03-24.[dead link]
- Seth Burgess (2002-09-18). "Debugging gimp-perl scripts; a how-to". Retrieved 2008-03-24.[dead link]
- Dov Grobgeld. "A Tutorial for Perl Gimp Users". Retrieved 2008-03-04.
- "Readme" (tgz). 1997-10-22. Retrieved 2008-03-24.
- "An online graphics generator powered by GIMP". Retrieved 2008-03-24.
- "Owen Taylors GTK Stuff". 1998-05-29. Retrieved 2008-03-24.
- "Boring news about Federico". Retrieved 2008-03-24.
- "Technical ramblings by Tim Janik". Retrieved 2012-11-06.
- "Mitchs blog". Retrieved 2008-03-24.
- "svenfoo". Retrieved 2008-03-24.
- "Changelog" (txt). 2000-12-24. Retrieved 2008-03-24.
- "News" (TXT). 2000-12-25. Retrieved 2008-03-24.
- "The GIMPressionist". Retrieved 2008-03-24.
- "Maurits thinks aloud". Retrieved 2008-03-24.
- What's New in The GIMP 2.2?
- "GIMP 2.6 Release Notes". Gimp.org. Retrieved 2009-01-24.
- 2.8 release notes