I am using Profilemaker 5 to make ICC profiles for RA4 papers printed on a Lightjet printer. The most saturated yellows available with the RA4 process are quite reddish compared to process yellow or the yellows of inkjet printers (and the Yellow primary of RGB working colour spaces such as Adobe RGB 1998).
When an RGB image (in Adobe RGB 1998) with very saturated yellows is printed (around 250 to 255R, 250-255G, 0-20B) the saturated yellows need to be mapped back into the printer’s available gamut. Unfortunately the result is a dull greenish yellow that is much less saturated than the most saturated yellow available in the RA4 process.
In essence the problem is that the Yellow primary of the RA4 paper has a different hue (more reddish) than the Yellow primary of the image (in Adobe RGB 1998).
Has anyone experienced this problem and are there any known solutions. I have tried editing the profiles to shift the saturated yellows towards the paper’s gamut but it tends to lead to banding.
Here is a screen grab from Colorthink that illustrates the problem.
Cool! An RA-4 question! I was thinking about the RA-4 process when I wrote the article on Profile Editing a few years ago.
When I was creating profiles for the RA-4 process using PM5, I found the opposite problem: The yellows were turning green. I had to edit the profile to move the yellows away from green and toward red. I imagine it depends on what kind of paper you are using [and whether you’ve changed the stabilizer lately 
] [that’s supposed to be a joke]
The gamut of your printer is what it is, so there’s not much you can do there. The only option is to wrestle your images into the gamut of your printer as well as you can. While PM5 is very good, I find others do a better job with extreme out of gamut shifts - like Monaco Profiler or the new i1Profiler. Maybe you could get your hands on one of those, at least for a test.
How are you doing the edits? If it were me, I’d use the Selective color tool, use an eye dropper to select the exact yellow primary of the image, and then move the “h” of LCH away from red. Perceptual rendering intent will tend to give you smoother transitions (less banding.)
Hi Patrick, Thanks for the reply. I may not have expressed it clearly but my experience is the same as yours. The yellows in the print become greenish. (not reddish) while the paper has the capacity to produce more saturated yellows if the hue is shifted towards red. I have tried the global editing procedure you suggest but have found it hard to achieve a result that works consistently without banding across many images.
If I introduce too strong a shift or too large a range, the yellow primary colours become more acceptable but the details in saturated yellows tend to flatten out.
I have generally used the Classic or Chroma Plus gamut mapping setting when creating the profiles but have just experimented with the Colorful setting and this does shift the yellow primary to a much redder value but also has the effect of losing detail in saturated yellows. It looks like a reasonable compromise for some situations.
I have been thinking of upgrading my Profilemaker to iProfiler so perhaps I will try that before investing too much time editing profiles in Profilemaker.
