On Sun, Jun 21, 2009 at 11:22 AM, peter sikking<peter@xxxxxxxxxxxx> 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 designingthis system - even though I suspect the vast majority of media will bewhite 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 myexpectations - I would love to hear from anyone who has usedauto-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 - onelight, one medium - on very dark blue. We originally placed the lightblue color behind the medium blue color (overprint). The clientchanged their mind, and I needed to remove the overprint. Mergingthe (inverted) contents of med blue into the contents of lt blueremoved the overprint in one step. I basically masked one plate withanother and applied the mask. While I doubt that function is necessary, it would certainly be veryuseful 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 thelayer stack. Yes - I envision a visibility toggle for each layer, andalso an opacity slider. But here's another murky area (as if weneeded more ;) - if I set a plate's opacity to 50%, does 100% black onthat plate print out at 50% or 100%? I would expect 100% - but that'sfrom past experience, and not very intuitive. Perhaps you are rightthat we need both a opacity and coverage control - that makes moresense to me, but I have never seen it implemented and may well proveconfusing. >> 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 - 3layers (or maybe 4 with a bg color)2. Create print projection, map layers to plates3. Done, hit print/export - OR4. Go back to RGB, duplicate two layers, merge them, apply curves, etc- whatever needs adjustment5. Manually apply the contents of the new layer to one or more of theplates in the projection6. 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 ormore 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 ifthe colors are not solid and/or you are mixing spot colors. Oftenfine-tuning is required. I would love to see automatic trapping(complicated!), but not without being able to manually tune theresults I'd like to thank everyone for participating in this discussion! Ilike the direction that this is headed...Chris_______________________________________________Gimp-developer mailing listGimp-developer@xxxxxxxxxxxxxxxxxxxxxxxxxxx://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
