TGA (Truevision Targa, .tga, .tpic)

Truevision's (now Pinnacle Systems) TGA File Format, often referred to as TARGA File Format, is a raster graphics file format. It was the native format of Truevision Inc.'s TARGA and VISTA boards, which were the first graphic cards for IBM-compatible PCs to support Highcolor/truecolor display. This family of graphic cards was intended for professional computer image synthesis and video editing with PCs; for this reason, usual resolutions of TGA image files match those of the NTSC and PAL video formats.

TARGA is an acronym for Truevision Advanced Raster Graphics Adapter; TGA is an initialism for Truevision Graphics Adapter. Today, most people refer to the format as the "TARGA File Format".

TGA files commonly have the extension ".tga" on PC DOS/Windows systems and Mac OS X (older Macintosh systems use the ".tpic" extension). The format can store image data with 1 - 32 bits of precision per pixel, - the maximum 24 bits of RGB and an extra 8-bit alpha channel. Color data can be color-mapped, or in directcolor or truecolor format; optionally, a lossless RLE compression can be employed.

The TGA file format was originally defined by AT&T EPICenter in 1984. AT&T EPICenter was an internal spin-off of AT&T created to market new technologies AT&T had developed for color frame buffers. What later became Truevision was the result of a leveraged employee buyout from AT&T in 1987.

EPICenter's first two cards, the VDA (video display adapter) and ICB (image capture board), used the first incarnations of the TGA file format. The file extensions ".vda" and ".icb" implied information about the board specific data contained. It was later determined by Alan Wlasuk (then head of EPICenter) and Brad Pillow that a more codified file format was needed. A very simple extension was made to what was already in use, and contained information on width, height, pixel depth, an associated color map and image origin. At the time, another technically superior file format called TIFF also appeared, but its use for true color imaging was initially more limited, as implementation of the TIFF specification was rather involved. The TGA file format's simplistic nature was what lead to its widespread adoption at the time.

Initially the TGA file format was used in the ICB-PAINT and TARGA-PAINT programs (what later became known as TIPS) and for several projects in online real estate browsing and still-frame video teleconferencing.

The current version (2.0) includes several enhancements such as "postage stamps" (better known as thumbnails), an alpha channel, gamma value, and textual metadata, and was authored by Truevision Inc.'s Shawn Steiner with help from Kevin Friedly and David Spoelstra in 1989.

At the time of its launching, it represented the state-of-the-art in digital image processing. Even today, though its maximum color depth is not well suited for high-end pre-press, intensive image processing systems, TGA is still used extensively throughout the animation and video industry because its primary intended outputs are standard TV screens, not color printed pages.

Uncompressed 24-bit TGA images are relatively simple compared to several other prominent 24-bit storage formats: A 24-bit TGA contains only an 18-byte header followed by the image data as packed RGB data. In contrast, BMP requires padding rows to 4-byte boundaries, TIFF and PNG are metadata containers that do not place the image data or attributes at a fixed location within the file.

Many games create screenshot files in TGA format.

• Star Wars Galaxies offers options for screenshots in TGA format, as well as JPG and BMP formats.
• Warcraft III creates screenshot files in TGA format.
• World of Warcraft creates screenshot files in the TGA format. [before 2.0 (i.e The Burning Crusade) when it switched to jpg format ]
• BeOS creates screenshot files in TGA format.
• POV-Ray engines natively use TGA for textures and height maps.
• Blender uses TGA as default for exporting UV-textures.
• The Unreal Editor uses TGA as an importing format for textures.
• Star Wars: Knights of the Old Republic II - The Sith Lords creates screenshot files in TGA format.
• World In Conflict creates screenshot files in TGA format.
• F/A-18 Hornet Operation Iraqi Freedom (OIF) uses TGA files for textures and bitmap graphics.
• Messiah from Shiny Entertainment has a screenshot feature; when F12 is pressed, a screenshot is saved in game directory. Additionally, TGA files are used as textures but are renamed with .001, .002, .003 etc extension. This can be discovered using Irfanview on these files, and it will respond saying about "This is a TGA file with wrong file extension."
• Team Fortress 2 creates screenshots with the TGA extension.
• Call of Duty 4 creates screenshots with the TGA extension.
• Second Life allows textures to be uploaded/imported as TARGA (.tga) format files.
• Glest uses textures in TGS format.
• Half-Life and Half-Life 2 uses TGAs for their skybox images
• Midtown Madness 2 uses TGA images to texture its landscape.
• Additionally, Nintendo Gamecube games store their files in .tga format.
  
  Source: en.wikipedia.org