yahvuu wrote: >> actually a question for peter (yahvuu): how complete is this >> overview? > > most notably, the porter-duff modes are not listed. > I'll have a look to make the overview as complete as possible.
I am interested in that. modes are like a box of chocolates, you'll never know what you gonna get. > first, I know now why our Darken section is one Shorter that our >> Lighten one: we are missing "subtractive" (that needs a name not >> soooo close to our Subtract). > > yeah, in photoshop, the names are: > 'subtractive' => 'linear burn' > 'additive' => 'linear dodge' > which is a lot better. > > It's still not perfect though, as the most prominent property of > burn/dodge > is the capability to increase the local contrast -- which is not > featured > by their 'linear' counterparts. But at least the confusion of > 'subtractive' > not actually using a subtraction term in the formula is avoided. well, we cannot rename addition (and it is a clear name at that), and linear burn is really not where I would like to go. After a look at the math (thanks for that) and a bit of brainstorming with nonsense names like "addition against all odds" or "orchestral addition in the dark" I arrived at something that does work: "Dark addition" (because it is an addition, shifted full range towards black). > Actually, i think the old 'subtract' mode should be removed, > when 'subtractive' gets added: just invert the blend layer and > you get the old 'subtract' mode back. no no no. everything stays there and keeps its name. file and user backward compatibility is needed here. that sounds very 'developer', and I fight a lot of these battles on the other side, but in this case it is true. > Along the same lines, what is the right to exist for 'divide'? > - it's just 'dogde' with an inverted blend layer. it is a straightforward mathematical mode, maybe used to prepare a mask for further use. it is part of the difference group that provides all kinds of mind-bending (inverting) stuff. after moving grain merge out I am happy to leave that group as-is. > An accepted pair of this type is grain extract/merge, for which > useful techniques exist , but also for dodge/divide?!? > If so, possibly the rest of the modes are candidates for > 'mode bloat', too, say a new mode: 'multiply with inverted blend > layer'... avoiding mode bloat is a good one. but please do not mix up the different reasons why modes are there right now. Like having a set of 'layer math' or simply results oriented (burn, lighten only). you see there are some very subtle reasons to add a new mode or not. I had some more fun with the heat maps in <http://yahvuu.files.wordpress.com/2009/09/table-brightness-1600.png> and I think I start to understand the algorithm-aesthetics better. as you pointed out, the lighten and darken groups are exclusively red or blue, which means that something like freeze/reflect do not fit there. then our overlay group modes have equal areas of red and blue in it. this makes heat/glow a better candidate then the two rows above or the one below them. then again there is no artistic value in that... --ps founder + principal interaction architect man + machine interface works http://mmiworks.net/blog : on interaction architecture _______________________________________________ Gimp-developer mailing list Gimp-developer@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer