[Award Winner] Bitmapped Images - The technical side of things explained.

[Midgardsormr]

That article does just fine up through Screen, then the details (i.e. the math) vanish. I had the same problem with the CGTextures tutorials (which I find far more enlightening than the Wikipedia article, by the way). Some of the blend modes are explained in great depth, and others just say something like
"Soft Light: Very much like Overlay, but the result is much more subtle." So what's going on in the channels that makes the effect more subtle?

[Redrobes]

Ahh, well the exact names that people give these things I cant help out with much. If its brightest, darkest, add, subtract, multiply, difference, invert (NOT), AND, OR, XOR. The other stuff like blur etc are not math functions but I can explain how to do those along with sharpen, emboss, edge enhancements or edge finding. But the more esoteric stuff like the buttonize, soft plastic, watercolor etc are all voodoo depending on what the programmer did. I don't think that these have exact specifications.

A lot of the non strict math stuff have a set of parameters - like the blur amount for example. In this regard soft light and hard light are algorithms that might consist of several so its a bit of a recipe or a vintage wine of taste to suit.