


Think about what you are saying here. The 24 bit image is quantised down to 8
bits so many 'similar' colours are mapped onto a single palette colour. This
colour gets modified in fairly arbitrary ways. You then want to apply these
modifications back to the 24 bit file, so you have to find which colours mapped
to this one palette colour. Ok you could do this by copying the 24 bit file to a
32 bit file and using the extra 8 bits to hold the index entry. 
Having done this, you need to do something to them ... what, exactly?

Apply the difference in RGB between the original and modified palette entry to
each colour in the group? This could generate colours with RGB outside the range
0...255. It would also lead to discontinuities when different parts of a smooth
colour gradient mapped to several different palette entries.

You could interpolate from full modification to no modification depending how
far each colour was from the palette entry. However I suspect this would look
rather odd.

So in summary, what I said in my previous posting still holds:



In other words, to edit a 24 bit file you need software built for the job.
Tacking mods onto xv is going to create more problems than it solves.

As to the other bits - you seemed to be claiming that there were bugs in XV. If
that was not what you meant, then:


Yes, I probably did. I found that the collected digest format of your posting
made it a little difficult to understand precisely what your point was. Sorry
if I misunderstood.


Yes again. What *is* (was?) wrong with xv?

--
Chris Lilley
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Technical Author, ITTI Computer Graphics and Visualisation Training Project
Computer Graphics Unit, Manchester Computing Centre, Oxford Road, 
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