Manipulating Raw Picture Data

[Mark Greenberg]

I have an image where different regions consist of known colors. I  
would like to fill a region with color at runtime as a sort of  
highlight. The situation does not lend itself to using separate  
transparent png images. I have been using the floodfill bucket tool  
to achieve this, but it is slow and doesn't work right when I compile  
to standalone.

I've read various threads on manipulating the raw picture data and  
seen a couple of stacks like that. It seems a bit beyond my skills as  
a casual programmer, but I may need to give it a try. Two questions:  
would sampling every pixel in a 600x400 image and possibly changing  
the pixel's color be fast enough to seem like a highlight to the  
user? and how would I go about doing that?

Thanks in Advance,

	Mark Greenberg