How far can I trust Photoshop's Gamut Warnings?

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just Tony
just Tony Veteran Member • Posts: 3,143
How far can I trust Photoshop's Gamut Warnings?

I would like to believe that a well crafted icc profile ought to have a reasonably accurate definition of the location of the gamut boundary. One requirement would be that the profile would have included a rich set of test samplings near the boundary. I'd want there to be small incremental steps between the color patches in order to narrow that band of uncertainty. Somebody will need to do careful work, the sort of commitment that a manufacturer of a printer and/or a paper has a strong vested interest in.

So I took a small look at what Photoshop has to say about a tiny range of printers on a microscopic range of papers (mostly Red River's Ultra Pro Satin 4). Is there good predictive value here?

I took screenshots of Photoshop which is internally using the Prophoto space. The image was tagged as Adobe RGB 1998 at the capture. The monitor is a wide gamut NEC.

Profiles for the Red River paper were downloaded from their web site. The Canon paper profiles were downloaded from their web site.

The comparison image, with no soft proofing or gamut warnings in use:

The Epson P800 has been my main printer for the last handful of years. I can report that I did have challenges getting the darker parts of the cherries - the same places where we see warnings below - to look the way I wanted in the prints. In this case I would say that I have reasonable faith in the locations of the warning:

The Canon Pro-1000 obtains an advantage by adding Red to the ink set, as expected:

Canon Pro-1000 with Red River Ultra Pro Satin 4

The Epson P5000 appears to generally go even further (for this particular image anyway) with thanks partly due to its added Orange ink I suppose:

Epson P5000 with Red River Ultra Pro Satin 4

Does being "wrong" = "not looking as nice"? Maybe it's not that simple.

I should say something about the result of the predicted color errors at the out of gamut locations for the Pro-1000 in places where the P5000 was declared to be more inclusive, for example the lower left rims of the cherries. The Canon profile was displaying those locations darker than the Epson would. In fact I like the appearance slightly better in the Canon soft proofing because it displays slightly higher tonal separations in those dark regions. So, an error can be a good thing sometimes.

I fully expect that it should be possible to obtain better dark red tonal separation with the P5000, but I'm not going to predict that the end result might look exactly the same as with the Pro-1000. Could they both be able to produce great prints of this image? I'm certain of it. Will either one be exactly the same as the monitor image? I'm certain that they would not.

The P900 is being predicted by PS to be a very slight backtrack from the P800 it replaces. i wouldn't draw general conclusions though without looking at a wider variety of paper profiles, particularly those from Epson itself. There's always a chance that Red River makes small errors in it's profiles. The predicted errors here are for dark tones that print slightly lighter.

Epson P900 with Red River Ultra Pro Satin 4

Now here's a gamut warning that I frankly don't trust - because there are no warnings at all! All of the blame might rest on Canon. This is their profile for their own "Lightweight Photo Paper" on their own Pro-1000. Note the small blocky reds that lack detail on the brightest portions of the foreground cherries at the "4 and 7 o'clock" positions at the rim of the bowl. Those aren't right. The lack of any warnings is also the case for their "Heavyweight" and "Extra Heavyweight" Photo Papers. The profiles of every other Canon paper have warnings.

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Wag more; bark less.

Nikon Coolpix P5000 Nikon Coolpix P900
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