Hello, Let me start by saying I haven't been following any development builds of GIMP or GEGL, so I may have some false presumptions and I certainly lack some information. That aside, I'd like to ask some broader questions about color spaces. Firstly, some background: the HSY color space appears to be much better than HSL, at least for some color operations. The package "PhotoPNMTools" operate in HSY mode and produce very nice output on their page of sample images. I'm not sure how the operation "Increase saturation 4x" is performed in GIMP, but when I use the Hue-Saturation tool and set Saturation to "100" four times the result is far worse than what is displayed on the sample images page (using GIMP 2.6.8). [ PhotoPNMTools: http://www.13thmonkey.org/~boris/photopnmtools/ ] [ Sample Images: http://www.13thmonkey.org/~boris/photopnmtools/saturation-test.html ] Using the PhotoPNMTools and the flower image, I've set the saturation to 4000 (on a scale of 0..1) and it still looks better than GIMP's output. I've also set the saturation to '2' four times in series. There is a difference between these two images (the saturation at 2 four times and at 4000) but the distorted parts of the image remain fairly consistent, so the algorithm appears to produce very stable results. Next, Windows Vista uses something called the Windows Color System, which uses CIECAM02 LMS space, ratified in 2008. I don't see any tools that work in this space for comparison with HSY, but it seems to be clear that there are a lot of different models of how colors can be displayed and manipulated. [ http://en.wikipedia.org/wiki/CIECAM02 ] My observations, now, are that the layer blend modes chose a color space based on some semi-abritrary criteria, and that this information isn't immediately obvious to the end user. Secondly, tools such as Hue-Saturation are fixed to the HLS color model. My thoughts are that this is too limiting, and I'd like to know what you think about the following: #1: Add additional color spaces to the color manipulation tools (HSV/HSL/HSY/RGB/Lab/LMS/CMYK/etc/etc), where appropriate. #2: Allow a tool configuration layer to appear as a node in a GEGL graph. #3: Remove the concept of explicit layer blend modes. So what we end up with is something like the following: - Image01 - + Layer Group 1 - - Layer Group 2 - - - Top Image - - : Saturation Tool in HSY-space @40% - - - Bottom Image - + Layer Group 3 ... etc. This is probably a very poor example and I'm sure I'm abusing some terminology, but I hope you get the gist of what I'm saying. "Layer Group 2" is an image-tool-image sandwich, which in current GIMP would be two images with a layer blend mode of "Saturation". But this way, instead of a fixed mode, we have something far more configurable. Unlike a layer mode it's not a fixed thing, so it should also be relatively future-proof as new modes or color spaces simply become new options for this tool layer. I expect some people will want to know what this "tool layer" looks like, and I'm thinking it would be something like a simple gray mask, but I'm more interested what people think about the concept at this time. Chris _______________________________________________ Gimp-developer mailing list Gimp-developer@xxxxxxxxxxxxxxxxxxxxxx https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
