Here’s the first (and still the best!) VB-based example that demonstrates how to correctly adjust an image’s contrast. I use DIB sections to maximize speed; it’s also worth mentioning that to perfectly determine contrast, you would have to first find the average brightness of the image – I use the shortcut method and assume that the average is 127 (close enough for our purposes).

Many people have used this code in various open-source VB projects, but rest assured: this is the original, most complete, most correct copy.