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From: marsha@acsu.buffalo.edu (john c marsha)
Newsgroups: comp.graphics
Subject: 24 bit SUN Rasterfile and Quaternions
Keywords: HELP!!!!!
Message-ID: <81735@eerie.acsu.Buffalo.EDU>
Date: 30 Jun 91 16:07:45 GMT
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ANY advice on this would be EXTREMELY helpful (i'm at the end of my rope)

I am almost finished with a program that raytraces Quaternions. I am
using an intensity function which returns the intensity values
in red, blue, and green for each pixel. I'd like to see the results
placed in a SUN Rasterfile format (RT_STANDARD,RGB_EQUAL_RGB is what i'm 
using now) but here are the problems:

1) With the ras_depth = 8, there are 256 color to choose from. Does
   anyone have a good algorithim for creating a 256 color colormap
   from the calculated intensites?

(e.g. If red[0],green[0],blue[0] intensites represent the first pixel
 on the screen, how can a colormap be created that allows red[500],
 green[500], blue[500] be the 501st  (0 to 500 is 501 numbers)
 pixel and still access 256 colors, obviously some of the 
 intensites have to be comprimised.) 


2) Is it possible for a SUN rasterfile to support 24 or higher bit depth?
   With 24 Bits:
   One could reference 16,777,215 colors.
   (this would mean a 200x200 image would have a length of
    120,000 bytes and the colormap length would be 360,000 bytes)

3) Isn't there a way to just say "here is the Red, Green and Blue
   intensites (relative to some scale i.e. 0 dark 255 bright) without
   using an actual image map? (ras_length = 0 but the maplength would
   be depth * width * height * 3 (one for each color).
   r[0],b[0],g[0] would actually be the pixel 0,0, not the 
   "reference" to the color)  

ARRRRGH!!!!!
(I have the image but I cant see it properly!!!!!!!)

If this is making no sense, i'll re-word it for a kind, helping soul.


Kevin (using a friend's account) 

BTW: If it helps, I'm running this on a SUN Sparc IPC w/ a 1024x1024 (?)
     screen.