How do I normalize an image?

Question

If I have a series of pixels, which range from say -500 to +1000, how would I normalize all the pixels on the same gradient so that they fall between a specific range, say 0

Answer 1

Some pseudocode like this would scale values linearly from one range to another

oldmin=-500
oldmax=1000
oldrange=oldmax-oldmin;

newmin=0
newmax=255;
newrange=newmax-newmin;

foreach(oldvalue)
{
    //where in the old scale is this value (0...1)
    scale=(oldvalue-oldmin)/oldrange;

    //place this scale in the new range
    newvalue=(newrange*scale)+newmin
}