COLORMAP

COLORMAP is a WAD lump which contains 34 maps that map colors down in brightness within a palette. Its main purpose is to allow Doom to show sectors with different light levels.

Each colormap is a table 256 bytes long. It is indexed using a pixel value (from 0 to 255) and yields a new, brightness-adjusted pixel value.

The first 32 colormaps (0-31) are used for sector brightness. Colormap 0 is the brightest and 31 is the darkest. Divide the sector brightness value (which ranges from 0 to 255) by 8, rounding down, and subtract from 31 to get the colormap to use. For example, a sector brightness of 7 uses map 31 while a brightness of 8 uses map 30.

The light amplification visor is implemented by ignoring brightness values and using colormap 0 for all sectors.

Colormap 32 is used when the player has the invulnerability powerup. Sector brightness is disregarded.

Colormap 33 is all black and its purpose is not known.