I'm using a Floyd-Steinburg dither to reduce the number of colors in

an image. To find the colors I need quickly, I'm using an inverse table-

a three-dimensional array indexed by color value yielding the color index

to put into the image.

Right now, I'm comparing each color position in the inverse table to

each color in the color lookup table to find the index I want. Since I'm

using the Pythagorean Theorem to find the distance, I'm executing thousands

of multiplications and it takes a long time (Macintosh Plus; 68000 at 8Mhz).

I must be missing something obvious, since I know that there are fast

implementations out there; such as in Apple's color QuickDraw software.

Please reply if you have any comments on:

o Fast ways of stuffing inverse color tables.

o Better ways of converting colors to color indices.

Thanks.

--

Kevin A. Mitchell (312) 266-4485

441 W. Huron UUCP: ..!uunet!dlogics!kam

Chicago, IL 60610 FAX: (312) 266-4473