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Thank you, I got really confused when the linked page started to discuss Photoshop blending modes and I had never considered they could be mapped directly to Porter-Duff ops.

As a graphics programmer I always want to point out that it's good to remember NONE of these are scientifically foundational. These are more or less just hacks that looks nice - pure heuristics that is. They are really pragmatic heuristics that produce nice outcomes.



I mean add and multiply pretty much work as expected (and I would say except for overlay, color, saturation and lumiosity they are the only ones you will ever need).


I would add to that list color dodge. Used in the right way, it produces results that mimic natural highlights. A highlight will impact all values except black (I.e. deep shadow) which it will ignore.

My teaching notes on color dodge here: https://rmit.instructure.com/courses/87565/modules/items/421...

On overlay (a very difficult blend mode to use) here: https://rmit.instructure.com/courses/87565/modules/items/408...

And on blnd modes in general here: https://rmit.instructure.com/courses/87565/modules/items/322...

Good to hear about porter/duff. Was news to me. The furthest back I go is 'Photoshop Channel Chops' Biedny, D., Monroy, B., & Moody, N. (1996). New Riders Publishing.




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