Re: The group's techniques, 2

Dan Margulis

On May 19, 2020, at 10:11 AM, Roberto Tartaglione <roberto@...> wrote:

Dear Dan,
I've applied your method on more images of the same kind
and I can confirm from my point of view that is a very reliable workflow, it can easily 
be automated too. Of course, it can not solve all multiple problems of 
a conversion in CMYK, but there are many ways to finish the job.

Correct. Usually this method is a good one for brightly colored RGB files that can’t be matched in CMYK. We see, however, that it is not the best way to handle this particular job. Also, Rick’s method of using ProPhoto RGB as a channel-blending source happens to work well in an exceptionally brilliant image like this one. In more normal work it wouldn’t make a difference, and if it did sRGB would likely be a better choice than ProPhoto.

You also offered me an important food for thought:
"A CMYK fact of life: the lighter the desired color, the worse the possible gamut mismatch. If we were doing pink flowers the problem would be much more severe, and we’d see a lot more variation in the quality of our corrections.”
In my professional life one of the harder (or perhaps The Harder) object to photographers has been Wine Rosè (although I was not involved in the Pre-press), but this is another story...

If you worked in France, where the rosés tend to be a paler pink, you wouldn’t have the problem. Italian winemakers prefer their rosatos to have a distinct hue, which can indeed be tricky to portray in CMYK. Worse, when they see your CMYK result, they say “you didn’t seem to have any difficulty with our reds and our whites, qual è il tuo cazzo problema?”

Which brings up a second question, the answer to which brings up a third. The author of #209, stung by the criticism that he had made the red robe too orange, submitted a new version to prove he knew how to make it rosier if that’s what the client wanted. Granted that the original saturation can’t be matched, I don’t see why it’s such a big deal to change hue as well. Personally, I think that the orange version seems a bit more violent than the others and therefore preferable.

But, as one of you remarked, this is exactly the kind of image where you show the client multiple versions. Not just because they might or might not like the orange-red, but because they probably won’t believe you when you say you can’t match the RGB red, just as they say that when Roberto’s reproduction of rosé wine is no good. Seeing multiple versions might convince them.

That brings up a third question, posted to me offline. How can we force more detail into the yellow purse? It isn’t difficult, but there’s one catch.

It may or may not be necessary to select the purse, but one way or another you need to find the current channel with the most detail (which will certainly be the blue, in this case), make a copy of it, increase contrast so that its lightest parts are blank, and then paste into the purse in Luminosity mode at some low opacity, possibly with an MMM action later.

If this were a red purse and the robe some other color, this method would work well. But yellow offers a particular trap. If you make the red robe slightly orange, as in #209, it isn’t necessarily bad. Nor would it necessarily be bad to make it a bit more purple. With yellow, it isn’t true. Make the purse slightly warmer and nobody will object. But make any part of it seem to have a greenish feel and the job gets rejected.

It happens that as yellow gets darker, people start to perceive greenness. So here, understanding that the blend has to be subtle, I would not use Luminosity mode. Instead I would make the blend twice as strong into the green channel as into the red.


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