On Fri, Jun 19, 2009 at 12:41 PM, peter sikking<peter@xxxxxxxxxxxx> wrote:> Chris Mohler wrote:>>>>>>> <http://www.mmiworks.net/eng/publications/2009/06/gimp-squaring-cmyk-circle.html>>>> I like this approach.>>>> I have a few questions:>>>> Will each plate have a density or opacity attribute? (some inks are>> more opaque than others)>> I guess that the complexities of ink simulation start showing here. Yes - although transparency/opacity would be enough for me to use GIMPfor professional separation work. I'm reasonably sure that PS uses avariant of the blending mode Multiply for spot channels, and thisworks fairly well. >> Will it be possible to edit an individual plate in grayscale?>> well, as pippin said: the individual plates _are_ grayscale/monochrome> drawables. they will be editable just like layer masks or selections. Excellent. >> And finally, will it be possible to perform operations on the RGB>> portion of the image that do not take (immediate) effect on the>> projection? For example, if I want to go back and add a portion of my>> RGB artwork to a plate, I might want to clone and existing RGB layer,>> perform some modifications, then apply the contents of that new layer>> to one of the plates.>>> I am curious why you want to do something like that, because you> are then going against the grain of the whole plan: freedom to develop> the artistic concept further without (much) rework on the plates. Imagine I'm designing a black t-shirt with say five spot colors,including white. After completing the artistic design, I enable the'projection screen'. This theoretically would result in my five"plates". However, the white plate will need special attention. Here's my workflow for this in PS: I would use the (badly named)'Apply Image' command to take the contents of each color plate andcombine them into the white plate using the mode 'multiply'. I wouldalso manually "choke" the white plate - this means making the whiteareas a point or two smaller than the colored areas, therebypreventing the white from poking out at the edges of the coloredareas. This process can get a bit tricky, especially if the originalartwork is very complex. Often, create temporary layers (or plates),perform selection/drawing functions, then combine the result back intoa plate in one of two ways - either making a selection on the templayer and going to the plate and filling or erasing, or using the'Apply Image' command to take the RGB channel of the current layer andcombine it with a plate using a mode such as Multiply, Screen, or Add. Now, I am quite interested in learning new workflows - so I am notbound to the "how" of the method above, but I hope I have explainedthe "why" well enough. In addition to being able to interact witheach plate as a grayscale drawable, it would be useful to createtemporary areas for doing work - be they layers, channels, plates,whatever - on which to create paths, selections, etc to in turn use tomodify the plates manually. Icing on the cake would be a mechanism tocombine/subtract plates using the available blending modes. Duringthe process, it is fairly critical to have an ink density/opacitysetting for each plate, to simulate (roughly) how the final print isgoing to look. EG, set the white plate at approx 90%, the colors atapprox 70% - and you can see which portions of the colors are fallingon the white underlay, and which portions are falling on the blackshirt. I realize that this is just one corner case, but if you visualize eachplate being printed separately, in order, you may be able to recognizesome of the many 'gotchas' inherent in separating the artistic artworkinto something suitable to send to the press. That's why (in myopinion) it is important to have as much control as possible over eachplate. Whew ;) If I explained any of this poorly, I am sorry and will happily try to do better. All in all, I am very pleased with the direction that this is takingand I would certainly like to use GIMP for even more of my productionwork. :) Thanks,Chris_______________________________________________Gimp-developer mailing listGimp-developer@xxxxxxxxxxxxxxxxxxxxxxxxxxx://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
