On Sun, Jun 21, 2009 at 11:22 AM, peter sikking<[email protected]> wrote:
>> 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 and >> combine them into the white plate using the mode 'multiply'. > > this looks analogue to me to black generation in cmyk, but now > inverted because we are on a black background. interesting concept, > the media color (makes note). since it is going to work for black, > it can be made to wok for any other color, with reversed logic also. Yes, I think media color should be taken into account when designing this system - even though I suspect the vast majority of media will be white or very light. >> I would >> also manually "choke" the white plate - this means making the white >> areas a point or two smaller than the colored areas, thereby >> preventing the white from poking out at the edges of the colored >> areas. > > this looks like trapping to me. is there a difference? > trapping set-up for each plate would be in the projection set-up. A "choke" is a trap of negative amount. This is probably just jargon - I suspect that it should in fact be called a negative trap. Automatic trapping (and overprinting) has never lived up to my expectations - I would love to hear from anyone who has used auto-trapping software with acceptable results though. >> Now, I am quite interested in learning new workflows - so I am not >> bound to the "how" of the method above, but I hope I have explained >> the "why" well enough. In addition to being able to interact with >> each plate as a grayscale drawable, it would be useful to create >> temporary areas for doing work - be they layers, channels, plates, >> whatever - on which to create paths, selections, etc to in turn use to >> modify the plates manually. > > everything of that will work on plates like working on layers today. > I am sure that global concepts like paths and selection will be > applicable to layers and plates without limits. a selection created > on a layer and applied to a plate: sure. OK - thanks for clarifying. >> Icing on the cake would be a mechanism to >> combine/subtract plates using the available blending modes. > > to generate plates from channels/layers that is needed, but > generating plates from plates? sounds like a creative kind > of workflow to me. I remember one specific instance: printing two blue colors - one light, one medium - on very dark blue. We originally placed the light blue color behind the medium blue color (overprint). The client changed their mind, and I needed to remove the overprint. Merging the (inverted) contents of med blue into the contents of lt blue removed the overprint in one step. I basically masked one plate with another and applied the mask. While I doubt that function is necessary, it would certainly be very useful on occasion. >> During >> the process, it is fairly critical to have an ink density/opacity >> setting for each plate, to simulate (roughly) how the final print is >> going to look. EG, set the white plate at approx 90%, the colors at >> approx 70% - and you can see which portions of the colors are falling >> on the white underlay, and which portions are falling on the black >> shirt. > > hmmm, tricky that one. it is natural for the plate stack to work > sort-of like the layer stack. eye symbols to switch plates on/off. > then there is the opacity slider of the layer stack. coverage slider > for the plates? ay be does the dual purpose of previewing like you > need and absolute print balancing. Indeed - the stack of plates should function more or less like the layer stack. Yes - I envision a visibility toggle for each layer, and also an opacity slider. But here's another murky area (as if we needed more ;) - if I set a plate's opacity to 50%, does 100% black on that plate print out at 50% or 100%? I would expect 100% - but that's from past experience, and not very intuitive. Perhaps you are right that we need both a opacity and coverage control - that makes more sense to me, but I have never seen it implemented and may well prove confusing. >> After re-reading the notes on the talk, if we have a Layer->Plate >> mapping, I think that will cover most situations. I would prefer a >> way to "mix" the plates, > > "mixing" channels + layers -> plates is a starting point for the > development of the design of the plate set-up. OK - thanks. >> and to be able to add new layers that could >> later be applied to new or existing plates, but this could be worked >> around. > > add layers where, image side or press projection side? My guess is image-side. One possible scenario: 1. Design artwork in GIMP - RGB, 3 colors, 1 color per layer - 3 layers (or maybe 4 with a bg color) 2. Create print projection, map layers to plates 3. Done, hit print/export - OR 4. Go back to RGB, duplicate two layers, merge them, apply curves, etc - whatever needs adjustment 5. Manually apply the contents of the new layer to one or more of the plates in the projection 6. Done, print/export I guess to summarize: in addition to the initial layer(or color?) -> plate mapping, it should be possible to re-apply contents of one or more RGB layer to the plates without re-mapping the entire projection (if that makes sense). Things like overprints and trapping can get very complicated, esp if the colors are not solid and/or you are mixing spot colors. Often fine-tuning is required. I would love to see automatic trapping (complicated!), but not without being able to manually tune the results I'd like to thank everyone for participating in this discussion! I like the direction that this is headed... Chris _______________________________________________ Gimp-developer mailing list [email protected] https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
