Re: Gum Tri-Color Yellow

Is all these really worth it?
RGB or CMYK?
You look a t your prints and if you don't like them you blame on CYMK or
RGB?
I blame on the pigment manufacturers and I am getting there when I read
Livick website.
Probably I miss something here but what I care is about my print and how
good they are and how confortable I feel about them.
I feel strong till I get a bad pigment and it takes a while to figure out
because you start thinking is something else.
Giovanni

----- Original Message -----
From: "Katharine Thayer" <kthayer@pacifier.com>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Sunday, July 11, 2004 6:16 PM
Subject: Re: Gum Tri-Color Yellow

> Keith Gerling wrote:
> >
> > Kate,
> >
> > I routinely use RGB, CMYK, and RGBK. I actually think RGB and RGBK (the
K
> > in this case is a skeletal black only) provides more of a success ratio,
> > i.e., the color balance in the print is more "true", and requires less
> > additional-coat-tweaking than CMYK. But it is difficult for me to look
at a
> > set of RGB negs and visualize what the resultant print will be, whereas
a
> > CMYK seems more "natural". So I tend to lean more toward CMYK.
>
> Interesting.
> >
> > But, and this is a HUGE BUT - all talk of CMYK as it relates to making
gum
> > prints is totally useless unless you consider the color space used. Your
> > talk of contrast as it relates to the "K" channel is impossible to
address
> > without knowing more. In Photoshop, for instance, the variations are
> > extreme between UCR and GCR. Within either of these, you have an
seemingly
> > infinite number of variations. Dot gain is somewhat important, but
> > especially critical are the Black Generation setting under GCR and the
ink
> > percentages. These settings are critical! I change them all around all
of
> > the time in order to get the effect I want. Perfectly color-true prints
can
> > be had with any of them, but the path to get there will be quite
different.
> >
> > Keith
>
>
> Keith is right. How much changing RGB to CMYK alters the color
> information in a file depends to a large extent, as Keith said, on
> whether the separations are GCR or UCR. It's important to be aware that
> Photoshop's default is GCR, which alters the color information much more
> than UCR.
>
> I chose a pixel in an RGB file and watched the info numbers when
> converting to CMYK using both algorithms. Under GCR a pixel that reads
> R=110, G=81, B=69, 65% density, when converted to CMYK became 40% C,
> 56%M, 57%Y, and 40% K, 65% density. The same pixel, starting with the
> same RGB values, converted to CMYK under OCR, became 58% C, 69% M, 73%Y,
> and 18% K, and 66% density.
>
> I've always done my color prints using the RGB file. I get excellent
> color balance using this method, and see no reason to change.
> Katharine
>
> >
> > -----Original Message-----
> > From: Kate M [mailto:kateb@paradise.net.nz]
> > Sent: Wednesday, July 07, 2004 8:53 PM
> > To: alt-photo-process-l@sask.usask.ca
> > Subject: RE: Gum Tri-Color Yellow
> >
> > I stand corrected for sending such a muddled message :$
> >
> > What I really meant to say was if you print CMY pigments with RGB negs,
> > in other words, C with the R channel neg, M with the G and Y with the B,
> > is the result (in the opinion of others) better, worse or equal to
> > printing the CMYK set of negs (all three colours plus black)? I do this
> > regularly and it works for colour balance and appropriate tone, although
> > I'm not happy with the overall contrast. I'm not sure if this is due to
> > my curves not being right or my printing processes.
> >
> > Supposedly ( and this is what I've read) using the RGB set of negatives
> > means that the contrast appropriate to the image is carried in the
> > colour layers, and when you print with CMYK the contrast is mostly
> > carried in the K (Key) layer. So you shouldn't print with CMY negs
> > without the K. Or am I just completely wrong??????
> >
> > -----Original Message-----
> > From: wrleigh@att.net [mailto:wrleigh@att.net]
> > Sent: Thursday, 8 July 2004 8:46 a.m.
> > To: alt-photo-process-l@sask.usask.ca
> > Subject: RE: Gum Tri-Color Yellow
> >
> > A minor terminology point: RGB is used for additive coloring and CMY[K}
> > is used for subtractive. Monitors are RGB, but printed matter is CMY[K}.
> > Printed things look black becasue the printing primaries of CMY
> > "subtract" colors of the other frequencies from the reflected light by
> > absorbing the other colors. When you see red printed matter, you are
> > seeing what is left over after the printed matter has absorbed the other
> > frequencies. If you are doing tri-color printing, you are using CMY, and
> > CMYK is CMY with a optional K to give a true black over the combination
> > of CMY.
> >
> > --
> > Bill Leigh
> > wrleigh@att.net
> >
> > >
> > > How many of you gum printers use four separations? I have read that
> > the
> > > K carries much of the contrast and therefore screws up colour balance.
> > I
> > > was just wondering who prefers RGB, who prints with CMYK??????
> > >
> > > Kate
> > >
> > > -----Original Message-----
> > > From: Katharine Thayer [mailto:kthayer@pacifier.com]
> > > Sent: Monday, 5 July 2004 1:25 a.m.
> > > To: alt-photo-process-l@sask.usask.ca
> > > Subject: Re: Gum Tri-Color Yellow
> > >
> > > Katharine Thayer wrote:
> > > >
> > > > Ender100@aol.com wrote:
> > > > >
> > > > > I wonder if the muddy brown is an issue not so much of the colors
> > > used, but perhaps poor color seperation in the negatives, or too fine
> > a
> > > screen in the seperate negatives. Larger dots of each color might give
> > > better color rendition, just as it does with inkjet printing and matte
> > > papers.
> > > > >
> > > > > Mark Nelson
> > > >
> > > > Not likely in my opinion. I haven't printed tricolor from continuous
> > > > tone negatives, although Dave has (sorry, I can't think of Dave's
> > last
> > > > name at the moment, but you know, Cowboy Dave) quite successfully; I
> > > > don't remember seeing any brown tones in his tricolor gums. I've
> > > > printed tricolors from many different types and resolutions of
> > digital
> > > > negatives, and I've never seen this brown tone in my own tricolor
> > work
> > > > from beginning to end. So I'm inclined to say it has little to do
> > with
> > > > the negative and much to do with the pigment. The fact that it
> > didn't
> > > > improve for Tom with different curves but it did improve when he
> > > > switched from PV19 to PR209 should be an indication right there (I'm
> > > > assuming he was using the same negatives).
> > > >
> > >
> > > This is not to say that I don't believe it's possible for someone to
> > > make really eccentric color separations that create weird color
> > > combinations, but why would anyone do that? Even if their intent was
> > to
> > > create weird color combinations; it seems to me that weird color
> > > combinations can be better (and more cheaply both in time and money
> > for
> > > negative materials) effected by choosing pigments that would create
> > > weird colors in combination with eeach other than by trying different
> > > weird color separations to see what happens, unless it's the
> > > unpredictability that interested one.
> > >
> > > Also want to make it clear that I don't think this brownish or
> > > brownish-purply cast has anything to do with how dilute or
> > concentrated
> > > the pigment is. I've printed with pigment concentrations ranging from
> > > totally saturated color to just a whisper of color for each of the
> > > primaries, and have never seen these brownish tones with the pigments
> > I
> > > use; the color combinations are clear and not brown no matter what the
> > > pigment concentration.
> > > Katharine
> > >
> > > ---
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Received on Sun Jul 11 23:37:35 2004