🚀 go-pugleaf

Hello Gernot. I hope all is well with you and that you had a good New Year.

I have ICC Profile Inspector but haven't used it much. I tried your experiment, but used ISO Coated, since I don't have the Fogra 27 profile on my system. I got similar results.

The following is speculation on my part, and is not backed up mathematically. It makes sense to me that adding yellow could result in reduced density, just like adding a little bit of white paint to a liter of black paint would give a slightly lighter color. I know...inks are more or less translucent, but I think the effect may still be similar. In fact, with the ISO Coated profile, I moved the Yellow slider to ), then I moved the Magenta slider from 15 to 14 and got a darker value, which suggests that with this profile, 100C/100M/100K doesn't give Dmax. You need to back off just a little bit on the Magenta ink to obtain the Dmax for this profile.

Also, I have built a lot of profiles in the past for B&W printing in QTR and IJC/OPM (using the Epson UC color inkset). To get a neutral profile, I would use combinations of light gray, light cyan, light magenta and sometimes yellow in the highlights and midtones. But, I never used yellow in the shadow areas. I used mostly Black (either MK or PK inks), plus sometimes a little dark cyan or dark magenta. The added dark inks sometimes increased Dmax, especially if black ink alone wouldn't do it, but I used them mainly to neutralize the warm tone of the Epson black inks. Adding too much of even the dark inks could result in a reduced Dmax by exceeding the ink limit of the paper. Adding yellow definitely reduced the Dmax. I never used any light inks at the shadow end. Perhaps this is the same thing you are seeing here.

I don't know how to obtain Dmax info from this program (or even if it is available).

Those are my thoughts after a quick look.

Lou