I am aware that this issue was raised in a previous thread about a year ago, but the need was not satisfied at that time, to the best of my knowledge. At best, a plugin was offered that only met one of the three features I describe below (arguably the least important of the three, no less). And worse, the solution at the time, a plugin, is no longer available for download. I was told that a newer plugin by the same developer reproduced that behavior, but I have not found any such functionality in the plugin. I think there was confusion in that recommendation – and anyway, as I said, that feature is the least critical of the three I recommend below anyway. The other two are far more important for satisfying the described need and use case.
PROBLEM:
Preparing images for inclusion in printed books requires satisfying a common CMYK restriction from the book-printers (e.g. IngramSpark): all images must not contain CMYK values above a total threshold (e.g. 240%) because the ink otherwise smears during printing. It would be great to enable the user to meet this requirement.
RECOMMENDED SOLUTION:
I believe the program would benefit from the following three tools or features:
- The CMYK selector should show the percentage sum of the CMYK components, some value between 0% and 400%.
- There should be a out-of-“gamut”-like overlay on the soft-proof view that reveals not “gamut” errors but locations where the CMYK value exceeds some user-specified limit (e.g. 240%, IngramSpark’s currently documented restriction at the time of this writing). This feature would go beyond mere eyedropper point-selections to enable the user to get a global overview of which regions of the image are out-of-spec with regard to various book printers’ restrictions.
- Most importantly, there need to be tools to actually enable the user to fix the problem. The two previous items merely help the user find such problems. There should be a way to paint or fill or level-limit or truncate (choose your favorite term) any over-limit values to some limiting value, the sum of which does not exceed the limit in question. In most cases, this will probably be black, since that is the most common way to accidentally exceed a book printer’s restriction, so simply remapping all illegal values to 0%,0%,0%,100% might work – but that is an oversimplification. I can imagine someone producing a color book who is still subject to a total ink limit. In such cases, there needs to be a way to remap over-limit pixels (or regions) to some other within-limit value (it could be any conceivable color of course). I’m not exactly sure how to do that, perhaps just linearly pull all four components down until the sum is within the limit. That would probably impose color shifts, it’s a hard problem to solve, but something has to be done in these cases. Otherwise book publishers will reject the images and the documents that contain them.