Re: Rel vs Abs proofs
Re: Rel vs Abs proofs
- Subject: Re: Rel vs Abs proofs
- From: Terry Wyse <email@hidden>
- Date: Thu, 12 Oct 2006 10:18:07 -0400
On Oct 12, 2006, at 4:05 AM, Rick Gordon wrote:
That being the case, might there not be a case to be made for a
hybrid colorimetric rendering that is essentially AbsCol except for
pure whites, but pure white where c0,m0,y0,k0 (or R255,G255,B255)
exists in the file? I would assume that, if you are converting
prior to printing, a blend-if layering of a AbsCol and a RelCol
rendering, where the AbsCol would be visible if the value on RelCol
layer is 0 to 254.
This is exactly what you can do with a GMG Colorproof RIP, although
this is a non-ICC option.
With GMG, by default it's an "absolute" match between Target (press)
and Current (inkjet) values. Once you've iterated the color match to
an acceptable delta e, you can then manually edit the paper
simulation in one of a couple of ways:
1) "Relative" where the paper tint is removed at pure white and them
smoothly reduced throughout the rest of the tone scale (100% of the
paper tint is removed at 0% ink, 50% is removed at 50% ink and so
on). And it doesn't have to be "all or nothing". If you have, say, 2%
c, 5%m and 10%y, you can elect to pull out just the "gray component"
value (2%c) and leave only the components that contribute to the
actual paper tint, leaving the correct paper tint color but with a
slighter higher L* (less dirty).
2) The "brute force" approach where you edit the profile/link table
directly and set paper white to 0,0,0,0 but leave the full paper tint
at any value greater than pure white. This gets you pure paper white
with absolute rendering everywhere else. This is rarely acceptable
however since at the first sign of a dot ("scum" dot), you'll get the
full effect of the paper simulation. It looks strange and unnatural
to say the least, especially if there's a rather large L* difference
between the proofing media and the press stock.
Roger, it looks to me like option #1 (assuming GMG is an option here)
would be your best bet. If you think about it, it offers the best of
both worlds. Because the paper white is smoothly reduced throughout
the "gamut", you'd get a more-or-less relative colorimetric look from
paper white throughout the quarter/mid-tones but with NO gamut
expansion at all in the solid primaries/secondaries. In practical
terms, it's much like a relative ICC rendering up to about the
quarter-tones but from there to 100%, it's basically an absolute ICC
rendering.
And also, might a case made for a range of proofing stocks targeted
specifically to various standard (or common) press stocks?
This is ALWAYS the best option. Find a proofing media that offers the
closest match to your primary or "house" press stock with perhaps a
slightly higher L* but with the same basic a*/b* values and use that.
There are several medias that I've worked with that are exactly that.
A couple that come to mind are GMG's Semimatte 250 and Satin 230 and
the ProofLine White Satin 230 medias. These all have L* values of
around 96-97 with b* values of between -2 to -3.5, perfect for #1/#2
coated/commercial proofing simulations. There's also a few medias out
there that offer a more publication type of paper white.
Regards,
Terry Wyse
_____________________________
WyseConsul
Color Management Consulting
G7 Certified Expert
email@hidden
704.843.0858
http://www.wyseconsul.com
http://www.colormanagementgroup.com
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