Image data may be stored raw, or optionally, a lossless RLE compression similar to PackBits can be employed.
EPICenter's first two cards, the VDA (video display adapter) and ICB (image capture board), used the first incarnations of the TGA file format.
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.
The TGA file format's simpler nature and portability between platforms is the main reason for its widespread adoption and its continued success in a wide variety of applications worldwide to this day.
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 direction from Kevin Friedly and David Spoelstra in 1989.
In contrast, BMP requires padding rows to 4-byte boundaries, while TIFF and PNG are metadata containers that do not place the image data or attributes at a fixed location within the file.
32-bit TGA images contain an alpha channel, or key signal, and are often used in character generator programs such as Avid Deko.
If a TGA decoder cannot interpret the information in the developer area, it will generally ignore it, since it is assumed to have been created by a different application.
The older version of the TGA file format specification taken from the Appendix C of the Truevision Technical Guide states that run-length encoded (RLE) packets may cross scan lines: "For the run length packet, the header is followed by a single color value, which is assumed to be repeated the number of times specified in the header.
However, page 24 of the TGA v2.0 specification states the exact opposite: "Run-length Packets should never encode pixels from more than one scan line.
Consequently TGA readers need to be able to handle RLE data packets that cross scan lines since this was part of the original specification.