вс, 6 нояб. 2022 г., 00:52 Igor Vladimirsky <[email protected]>:
> > > ср, 2 нояб. 2022 г. в 12:53, Andrew Randrianasulu <[email protected] > >: > >> So, as Igor noticed CinGG's divide and subtract modes do not behave like >> they behaved in Cin HV/CV/CVE I digged into matter a bit and found few >> confusing (for me, amateur) things...... >> > But moreover, according to documentation CinGG composites tracks a bit >> backward comparing to photo editors: >> >> > I found this in my archive. > Very cool, thanks! So, for your specific preferences does inverting S and D in overlayframe.h for subtract and divide return familiar behavior, especially with huge use of reroute/inversion? I do not think making it new default unconditionally will be good, because some modes compositing this way and some - that way add too much confusion, but a) you can use personal patch and hopefully b) I'll find some way to make this behavior configurable .... In 2016, I asked GoodGuy about the Divide blend mode. > I showed him a quote from from Changelog 2.1 > https://github.com/cinelerra-cv-team/cinelerra-cv/blob/master/cinelerra/CHANGELOG.2.1 > Quote:*" For overlaying, divide behavior is the same as the Gimp.* > New overlaying algorithm: Max takes the maximum r, g, and b values." > > *GG's answer:* > *------------------------------------* > > > > > > > > > > > > > *"This is the math form Gimp currently uses:STD_BLEND + (Sa == 0.0 || Dc / > Sc > Da / Sa ? Sa * Da : Dc * Sa * Sa / Sc)HV 4.6.1 (and CV) actually > uses:(Sc > 0 ? Dc / Sc : 1)Cin5 actually uses:(Dc > 0 ? Sc / Dc : 0)So, > none of these look like Gimp. But Divide is a bit squirrelly. It can fail > on a per pixel basis because of divide by zero. I prefer src (top track) / > dst (btm track) with divide by zero as black (not white). I think this is > the way most would like to see it work, since it is a stack of operations, > and it easier to work up from zero, than down from 1."* > *---------------------------------------* > > ---------------------------------------- > > This is from CGG'code > Cinelerra-GG > // DIVIDE [Sa + Da - Sa*Da, Sc*(1 - Da) + Dc*(1 - Sa) + Sc / Dc] > // SUBTRACT [(Sa - Da), (Sc - Dc)] > > > But in HV and CV*, the Subtract and Divide blend modes work the same way > as GIMP, Photoshop, Adobe Premiere Pro, EDIUS > > *GIMP* > Divide mode multiplies each pixel value in the lower layer by 256 and then > divides that by the corresponding pixel value of the upper layer plus one. > Subtract mode subtracts the pixel values of the upper layer from the pixel > values of the lower layer. > > *Photoshop* > https://photoblogstop.com/photoshop/photoshop-blend-modes-explained > Divide > Background layer ÷ Active layer = Quotient > Subtract > B minus A > > *Adobe Premiere Pro* > https://helpx.adobe.com/premiere-pro/using/blending-modes.html > Divide > Divides underlying color by source color. If the source color is white, > the result color is the underlying color. Result color values can be > greater than 1.0 in 32-bpc projects. > Subtract > Subtracts the source file from the underlying color. If the source color > is black, the result color is the underlying color. Result color values can > be less than 0 in 32-bpc project > > *EDIUS *(quote from its manual) > Subtract > Subtracts the overlay color values from the background. >
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