Re: TAC and "Total Ink Limit"
Re: TAC and "Total Ink Limit"
- Subject: Re: TAC and "Total Ink Limit"
- From: Terry Wyse <email@hidden>
- Date: Thu, 03 Jul 2003 10:42:27 -0400
on 7/3/03 9:27 AM, CS Carl Stawicki (4211) wrote:
>
If I convert a 0rgb to US Web Coated (SWOP)v2, I get 75c 68m 67y 90k, which
>
equals exactly 300% total ink (Perc., BPC on). Now, I have 2 questions: What
>
are the values of this color that ends up on plate, and what are the values
>
that end up on press? (this is a computer-to-plate process)
In theory, you'll get the same values on plate that's in your file. In
practice, the printer may have compensation curves being applied to the
plate. That's OK as they are probably applying plate curves to achieve a
more-or-less standard amount of dot gain on press. The main thing to
consider is that your press profile targets roughly the same dot gain (TVI)
values that they expect to get on press. It's only when you
>
>
All the values output the same on plate, and gain on press. If this is
>
correct, then I will end up with higher values on press. If you account for
>
a 20% dot gain (just to keep it simple), the original 75c 68m 67y 90k in my
>
Photoshop file would end up gaining to 89c 84m 84y 96k, equaling 353%, which
>
exceeds the TAC of Swop (300%). Is my reasoning correct?
Incorrect. The TAC is only considered for the actual values in your image.
While 20-22% dot gain is the EXPECTED amount on press, the TAC value is not
part of this. Another way to look at is the TAC only refers to the physical
values on plate and press and not the final dot area values as measured by a
densitometer. Remember, nearly HALF the "dot gain" on press is purely
optical gain (about 10-12%) where the physical dot hasn't changed at all.
The rest of the measured dot gain is physical gain. At any rate, all the TAC
values, etc., already take into account the expected dot gain on press.
Hope this helps,
Terry
--
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