Re: Images and TAC values
Re: Images and TAC values
- Subject: Re: Images and TAC values
- From: Mark Stegman <email@hidden>
- Date: Sat, 13 Dec 2014 17:04:21 +1100
Roger,
On Sat, Dec 13, 2014 at 1:12 PM, Roger Breton <email@hidden> wrote:
>
> This is an interesting conversation.
>
> First, I want to salute Martin's original suggestion to do a Profile to
> Profile conversion or Proofing Setup in order to trigger a Gamut Warning. I
> ought to try this trick but, I suspect it won't be of much help for me :(
>
>
I missed that however, as you originally said, I don't think Gamut View
addresses the problem of alerting you to exceeding TIL/TAC. As Terry points
out exceeding TAC this will have little effect on the gamut. TAC is about
the maximum ink limit for a specific printing process - the darkest shadows
where there is little or no colour. It will result in less detail and other
associated problems that result from trying to put more ink on the paper
than the printing process can tolerate. As any printer will know putting
more ink on the paper doesn't necessarily lead to more colour, darker
shadows and or higher densities. The advantage of Gamut View is in
displaying those COLOURS that will be clipped when converting to another
colour space.
Second, I agree this new "Viewing option" should be located under the View
> menu. That's a no brainer.
>
Agreed.
>
> Third, I often run in exceeding the prescribed TIL when editing images
> myself. So I can vouch to the usefulness of such a viewing option in
> Photoshop. I remember, once, using the Curves tool, to satisfy the craving
> for a client for contrast; by pulling the black point in from the right, on
> a CMYK image, all of a sudden, the darkest tones of the image, that were
> already well mapped to a max of 300%, became 310%, 320%, 340% and so on.
> And I did not pay attention to the fact that the extra contrast I was
> witnessing was achieved at the expense of overstepping the 300% boundary.
> By the time I realize my "oversight" it was too late. Needless to say I
> didn't do the same mistake twice but suffice to say that, had I had access
> to a "TIL Preview" somewhere, in Photoshop, a mode I could have turned on,
> à la Gamut Warning, I would have seen the mistake I was making. This could
> have taken the form of red pixels overlaid on the image, indicating an
> excess of a selected maximum TIL. Then, having been "warned" that way by
> Photoshop, it would have been a matter of deciding which pixels to push
> closer to the 300% boundary.
>
I believe this is a trap of working in CMYK. If you had been making your
adjustment in RGB and previewing them using the Proof Setup you would have
seen the result of the targeted conversion and known what to expect in
terms of gamut mapping. As Andrew has pointed on this forum numerous times
Gamut View is very limited in what it can show you just by the fact that it
covers everything that is OoG with a flat grey daub. It doesn't distinguish
OoG colours by the amount they go beyond the the limits of the printing
condition. For this reason Proof Setup is preferable but it only to alert
you to how mostly saturated colours will be affected. What you need to
explain to your client is that, while they may not like the result of the
conversion there is little that you can do about it other than using an
entirely different printing process. The resultant conversion will apply
the appropriate values for the targeted printing condition, including
TAC/TIL. How you optimise each image for that conversion is another
story... and a very subjective one at that.
>
> No offense, Martin, but in this case, I tend to think that, a P2P proofing
> setup is a "poor man" TIL Preview. And I fail to see this as a feature that
> could be tied to ICC workflow? I tend to see it as a straightforward,
> mechanical kind of "Device CMYK" dumb interface. Flip it on, flip in off.
> You need it? You activate it. You don't? You hide it. No mess, no fuss.
> Instant gratification. To me, it has nothing to do with Gamut Warning. But,
> again, no offense and I'll gladly give your trick a try until Adobe comes
> up with an update with that viewing option, in a future update.
>
Me too.
Mark
>
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