The Targa File Format (TGA)

The success of the Targa (TGA) file format for storing color images can be attributed to its ease of use, the small amount of program memory needed to parse the file, and the fact that it was the first true-color file format widely available. Truevision defined the TGA file format in 1984 for use with its first videographics products. Since then, it has been estimated that today over 80 percent of the color images stored on hard drives employ some variation of the TGA file format. Many government offices, corporations, service bureaus, productions shops and nearly all Truevision developers have standardized on the TGA format as a means of allowing cross-product and cross-application compatibility.

The original Truevision TGA file format has been widely accepted by the graphics industry. However, newer technology and techniques have created the need for additional image information to be recorded in the file. In 1989, Truevision introduced extensions to the TGA file format to satisfy requests made by the graphics industry and to ensure that the standard will meet future needs of the color imaging marketplace. The extensions are optional and will have no impact on existing packages (assuming the packages followed the original TGA file format guidelines). In particular, the new TGA file format addresses the following needs:

          Thumbnail copy of the stored image

          Date and time of file creation

          Author name

          Author comments

          Job name

          Job accumulated time

          Gamma value

          Correct color LUT

          Pixel aspect ratio

          Scan line offset table

          Key color

          Software package name and version number

          Developer definable areas

          Attribute (alpha) channel type

          The ability for simple expansion