am42+@andrew.cmu.edu (Alexander Paul Morris) (01/31/91)
I have some 24-bit true color images that I'd like to display on a 256
color vga adapter. But I can't seem to translate the appropriate
colors. First
of all, the vga palette is on 18 bits, so color resolution is already
lost there. But if all I were doing was going from 24-bit to 18-bit
rgb, it would not really be a problem. But going to 256 colors (8-bit),
I don't know which of the 18-bit palette to place into the 256 color
positions. Has anyone done any work with this? Does anyone have any
idea on how to get a good palette from this? I know it can be done
because PicLab 1.82 did it (though it took some time), and I used Piclab
to convert the 3 raw color palettes into a 24-bit Targa file and
displayed it with VPIC and instantly the picture came up with the
correct palette. As far as I know, targa files don't hold a palette, so
VPIC must have some great formula or instant transform to do the
conversion. Please help me figure this out, or find that formula, or
something! Thanks in advance.
Alexander Morris "People die, things change...
Carnegie Mellon It's sad."
Alexander Morris "People die, things change...
Carnegie Mellon It's sad."dsmith@hplabsb.HP.COM (David Smith) (02/02/91)
In article <8bduSJW00WBMQ4js58@andrew.cmu.edu> am42+@andrew.cmu.edu (Alexander Paul Morris) writes: >I have some 24-bit true color images that I'd like to display on a 256 >color vga adapter. >I don't know which of the 18-bit palette to place into the 256 color >positions. One way is to use 3 bits each of red and green, and 2 bits of blue. Another is to use 7 levels of green, 6 of red, and 5 of blue. Then you halftone the colors onto the screen using error diffusion or dither. -- David R. Smith, HP Labs | "There are two kinds of truth. dsmith@hplabs.hp.com | There are real truths, (415) 857-7898 | and there are made-up truths." | - Marion Barry (USN&WR 12/31/90 p18)