View source for Atari ST color palette

== Format details ==
In a number of Atari graphics formats, the palette is stored in a format with 16 bits per palette entry, only 9 of which are significant:
 xx xx xx xx xx R2 R1 R0  xx G2 G1 G0 xx B2 B1 B0

=== Atari STE palettes ===
The Atari "STE" models increased the color depth from 3 to 4 bits per color channel, thus supporting (2^4)^3 = 4096 different colors. For compatibility reasons, its palettes have the least significant bit in the position one might otherwise expect to be used for the ''most'' significant bit:
 xx xx xx xx R0 R3 R2 R1  G0 G3 G2 G1 B0 B3 B2 B1

Some Atari image files use these Atari STE 12-bit palettes, usually with no external indication that they do so. Trying to detect and interpret such palettes is a good idea, as grayscale (and grayscale-ish) images can be significantly improved by the extra color depth. (Unfortunately, it seems that some non-STE files contain garbage (or private data) in the unused bits, instead of zeroes. So, autodetecting STE palettes may not be possible to do in a completely reliable way.)

=== Spectrum 512 Enhanced palettes ===
For completeness, we mention the obscure [[Spectrum 512 formats|Spectrum 512]] "Enhanced" format, which extends the palette even further, to 5 bits per color channel:
 R0 G0 B0 xx R1 R4 R3 R2  G1 G4 G3 G2 B1 B4 B3 B2

=== Bi-level images ===
''[TODO: Explain how palettes for bi-level "high resolution" modes should be interpreted (if they should be interpreted at all). In practice, many such palettes contain white and black as expected, but others contain improbable colors such as dark blue and black, or red and white.]''