DrDre said:
The simple white balancing algorithm is almost an exact copy of the algorithm used in GIMP …Well, it looks like I’ve re-invented the wheel! This is my general approach to manual color (& fade) correction. (Never attempted to automate it, but the approach is simple enough to work up something.)
My approach differs from GIMP’s:
I never discard picture information as GIMP does by cutting off pixels
pic2 – What should be black-ish and white-sh R-G-B’s are set by end-cut-offs of blank area to achieve those values (looks very close to your pic)
pic3 – What should be middle-grey-ish R-G-B’s are set by gamma to achieve those values
pic4 – Contrast is then adjusted (scene specific – can’t see this being automated as yet) and …
pic4 – Spectrum ends are under-max’ed by 16 pixels for foot-room & head-room
And thanks for the reference leads. Didn’t know Google was a Scholar, too!
I actually don’t cut-off pixels either, but I do us the 0.05% percentile to define the neutral “white” point, for the “simple” white balance.