Re: color printing for dummies
Then, which color to print with which separation: cyan (blue) with
the red separation, magenta (red) with the green separation, and
yellow with the blue separation. That's if you create the RGB>CMY
separations by inverting the channels individually. If you use the
"multichannel" method described in James, the separations come out
named CMY and you use them straightforwardly. With CMYK it's
straightforward, use the separations as named.
perfect, thanks. that was the answer i was looking for. using one
straightford and the other one not, was what put my brain into a big
knot. i was really starting to wonder, why no one spent even a small
paragraph on it,,,,i looked and looked and didn't find anything.
thanks too to chris nze. the christopher james book is very informative.
i didn't know that one before. i definitely saved a copy to my harddisk.
the description of the tony gonzales workflow is very interesting.
and i already went and bought some phthaloblue and scarlet red. it was a
pretty sudden decision to try a full-color gum on the week end and i
just used what i had at home.
thanks a million for helping me out here
phritz
Katharine Thayer schrieb:
Hi phritz,
First, I'd say your blue (payne's grey) is too weak to balance your
red and yellow; I'd recommend a more definite blue (pthalo, prussian,
ultramarine or indanthrone) or a less definite red and yellow (that
would give you a softer, more unsaturated color palette with the
payne's grey. Yellow ochre and burnt umber can work well with payne's
grey for that purpose).
Then, which color to print with which separation: cyan (blue) with
the red separation, magenta (red) with the green separation, and
yellow with the blue separation. That's if you create the RGB>CMY
separations by inverting the channels individually. If you use the
"multichannel" method described in James, the separations come out
named CMY and you use them straightforwardly. With CMYK it's
straightforward, use the separations as named.
For more detailed information:
http://www.pacifier.com/~kthayer/html/RGBseps.html
http://www.pacifier.com/~kthayer/html/CMYK.html
http://www.pacifier.com/~kthayer/html/tricolor.html
Katharine
On Feb 10, 2009, at 7:51 AM, phritz phantom wrote:
i really need some help here. i searched the internet for hours
yesterday, to no avail. could someone recommend me a good tutorial
for color printing for alternative processes (esp. gum printing)?
i dabbled in color gum printing for the first time some days ago. i
tried rgb-separations from photoshop and exposed three layers: one
for cadmium-yellow, cadmium red and payne's grey each (i know not the
best choice).
i think the outcome was somewhat successful. at least the green on
the chest looks pretty much like in the original. so i can't be that
far off...
http://i31.photobucket.com/albums/c367/phritz/01-1.jpg?t=1234279590
ok, since i really have no idea about color printing, at first i
thought, i could just invert the image, split channels (getting three
images.one labelled r, one g, one b), and use the r-one for the red
layer etc....
looking at the negs, i managed to find out (of course the red parts
in the original images have to be the thinnest areas in the neg for
the red emulsion layer) that i have to use the opposite colours: the
r-channel for the yellow emulsion....
now i wanted to play around a little with other pics, curves and cmyk
separations... now cmyk separations is really where my knowledge
comes to an end. do i have to use the opposite colours with cmyk too
after inverting and splitting channels?
the k-negative looks like it should be used with the black pigment
emulsion... and the others?
i know this is very basic stuff and i'm a little embarrassed that i
can't find it out by myself. but i really wasn't able to find a
suitable tutorial for that. all that negative, opposite colours and
inverting makes me dizzy.
how do i find out which separation is the suitable negative for which
pigment emulsion?
thanks for the help,
phritz
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