SHADTEX V1.06 is a FREEWARE program for helping prepare "TexPolyShading" 
texture files. A "TexPolyShading" texture file consists of eight 32 pixel 
wide bands, placed beside each other in a standard r8 texture file. Each 
successive 'band' represents a different shading condition, and each is 
therefore darker than the one before it. The program takes a 32 pixel (or 
less) wide texture (saved as a PNG file) as its input, and then sets about 
dimming the colours for each successive band, copying the bands to their 
correct locations at the same time. The resultant texture file can be saved 
as either a flight-sim compatible r8 file, or a PNG file ready for further 
editing.

by Andrew Roach <aroach@geocities.com>