Imagine a 24 bit bitmap (true color). And suppose you want to make a specific area of the bitmap darker, e.g. a pixel with RGB value (x,y,z) should become (x/2, y/2, z/2). By dividing each pixel by a certain amount, the effect of darkening is achieved.
Iterating through the entire bitmap by manipulating each pixel seperately is one possibility (a relatively slow one). On the other hand a tried a lot of BitBlt's, but unfortunately with no success....
Is there anyone who know an efficient algorithm??
Thanks!!