I accept that the wording is technically incorrect. I was describing what I saw happen in a color wheel, and that was how it appeared to me. I will fix it.
Yes correct. I thought it obvious that if the idea applied to yellow it also applied to the others, and didn’t want to type it all out. But it is tricky and Bill looks to have a sound understanding of it.
I should note also that that if you increase red in green, you might not see the shift from yellow > orange unless the yellow is desaturated. You won’t see it if yellow is fully saturated, as a full saturated yellow is 255 R 255 G, and R can’t be increased beyond that. Playing with channel mixer and a hue wheel that features only 100% saturated colours won’t show this, but a desaturated hue wheel, and real world photographs, will.
Yep, but adding a ‘sine-like’ curve to compress the dynamic range will lead to loss of local contrast (a bright pixel next to a dark one will become less bright, with the dark pixel becoming less dark at the same time), whereas with the guided filter (‘preserve details’), a different exposure setting is applied to each area in the image (depending on its average brightness), so local contrast is preserved (in a dark area, the bright pixel next to a dark one will become even brighter, and the dark pixel will become less dark). Of course, both modes have their uses.
There is also the “averaged guided filter” option, which is a useful mid way approach
I have put together a pdf, complete with coloured tables, to demonstrate how the channel mixer works. Hopefully it makes things a bit clearer. If you spot any errors let me know.
Edit: I’ve worked out the exact formula for predicting how colours will change, and am updating tables accordingly. It will add more colours than I have names for, but since its available I might as well get precise accuracy.
Edit 2: Here is the updated pdf.
Edit 3: Fixed a few small errors, and improved analysis.
The Channel Mixer.pdf (68.9 KB)
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Very nice chart!
“Now to really make your head spin, try increasing and decreasing in multiple directions, in multiple channels!”
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