Hello Martin, On Mon, Nov 10, 2008 at 8:18 AM, Martin Nordholts <enselic@xxxxxxxxx> wrote: > Hi David > > David Gowers wrote: >> Ah, so if I want to make the result preserve the alpha of the >> underlying layer, I'll need to do that via layer mask? >> > > Exactly, masking should generally be performed *after* blending with the > new layer mode compositing model. Cool, I like this, it certainly is more consistent :) > >> FWIW, since you changed the meaning of the layer modes, is this a good >> time to make compositing gamma-correct? > > Yes definitely. In fact, layer mode compositing with GEGL _does_ work on > data with gamma = 1.0. That is, the layer mode blending occurs on color > data in the babl format "RaGaBaA float", i.e pre-multiplied, linear > light 32 bit per channel RGBA. > > The reason you don't see a difference when toggling Use GEGL is that now > during development the source data, namely the data from the tiles of > the TileManagers of the GimpDrawables, are treated as if containing > color data in the babl format "RGBA u8", i.e. linear light 8 bit per > channel RGBA. A more correct assumption would be "R'G'B'A u8", i.e. Thank you for explaining that, it was just what I suspected :) I'll see what happens when I make that change :) (apparently just one line, app/core/gimpprojection.c:391, is needed to be changed to implement this now :D) > gamma corrected RGBA. > > The long term goal is of course to make sure color space conversions are > correct throughout the whole image processing pipeline, taking into > account the current color profile of the image etc. So eventually we need to be able to construct on-demand babl_formats which utilize arbitrary profiles, and have babl depend on lcms to get a acceptably quick transform between those and the standard spaces? And recognize the use of standard colorspace profiles (eg sRGB, linear-light RGB) so we can get faster processing for them? David -- Reticience and self-censorship is a farce. The deceiver does not himself know the truth, anything that he holds back he holds back not only from others but from himself. Fuck censorship. "I yam what I yam." _______________________________________________ Gimp-developer mailing list Gimp-developer@xxxxxxxxxxxxxxxxxxxxxx https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
