-Divide (brightens photos)
-Addition (too many whites)
-Subtract (too many blacks)
-Difference (subtract with scaling)
-Darken fblend(a,b)=min(a,b) for RGB
-Lighten fblend(a,b)=max(a,b) for RGB
multiply fblend(a,b)=ab
darker
Screen fblend(a,b)=1-(1-a)(1-b)
brighter
Dodge and burn
-dodge and burn change the lightness of the pictures
-dodging lightens an image, while burning darkens it
-dodge builds on screen mode
-burn build on multiply mode
-there are numerous variations of each!
Darken