On Sun, Jun 21, 2009 at 11:22 AM, peter sikking<pe...@mmiworks.net> 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

>> 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

I'd like to thank everyone for participating in this discussion!  I
like the direction that this is headed...
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