CHROMiX

Profile plots

Not only do I want good printer profiles, I want to understand what’s going on. There is an admittedly steep learning curve on this and I freely admit that I am on the early and steep part. I’m trying to use ColorThink to gain insight. I’ve made some print profiles for my Epson 3800 and have been graphing them. Learned some interesting things like, Epson Hot Press Natural, a fine art matte paper shows greater high luminance gamut (not sure if that’s a proper term, feel free to correct me…)in the yellows than my favorite Baryta paper, the Ilford Galerie Gold Fiber silk.

All that aside, my question regards the plots. The 2d plot shows some jagged edges, while the 3d plot is smoother in all areas, more of what I expected.

Why the jagged edges? Does this suggest that the profile can be easily improved or operator error on my part?

Thanks,

Fred

Hi Fred,

Most of the time the 2D outline matches the 3D shape pretty closely. If it does not, it could be because your gamut has some unusual projections or twists. And this is often due to a bad profile or bad measurement data used to make the profile. In a few rare cases, it might be due to a problem in ColorThink. For example I know that the 2D projection of ProPhotoRGB does not graph correctly in Yxy space.

Email your profile to me and I’ll take a look at it. We should be able to figure out what’s going on.

BTW, getting ColorThink is a great way to shorten your learning curve. You’re doing the right thing!

Pat,

Thanks for the offer to look at my profile. I’ve compared my profile to the canned Ilford profile (this is for Ilford Galerie Gold Fibre Silk) and the Ilford profile shows even greater “jagged edges” than the one I generated using i1 profiler. My i1 profile even shows a markedly greater gamut in the greens. I’ll send it along if you don’t mind giving it a quick look, I suspect though that I’m just a bit unfamiliar with what to look for and all is well.

While I have you on the line though… Your message on the forum regarding the 3.03 release indicated that there are “support of new profiling tools (i1Profiler),” can’t really figure out how colorthink is supporting i1 profiler differently

Like a lot of the changes that we rolled into CT recently, it is fixing a pretty minor thing, that you might not notice. This one was actually brought up in these forums. This thread talks about the curves using the perceptual rendering intent for i1Profiler profiles. They were wacky, and now the curves are presented correctly.

Concerning your profile, the 3D graph looks very smooth so I doubt there is anything wrong with your profile. If you’re looking at the little magenta bump in the 2D projection, I don’t think that’s anything to worry about. Send me anything more you’d like me to check out.

I would be very surprised and even perhaps a little worried if most any gloss or luster paper profile showed a larger gamut in the area you mention, in the brightest highlight tones in the yellows (and other similar colours).
Just FYI, it isn’t high luminance in the areas of the gamut you mention as paper is not (and cannot be) luminescant, it’s reflective. Easiest terminology to use is shadow [tones], 3/4 tones, midtones, 1/4 tones and highlights - this way the specific part of the gamut you’re talking about is self-explanatory. And that’s what the rest of the industry and photographers use.

Getting back to your profile and the greater gamut in the yellow highlight tones, most, if not all matte papers wil show what you are seeing, when compared with a gloss or semigloss/luster paper. The shadow tones will greatly favour the gloss/luster papers and show a larger gamut in those regions just as at the opposite end of the gamut, in the highlights, matte papers have the greater gamut area. This is inherant to the paper type, not printer, inks, etc.

So what you’re seeing is perfectly normal and in fact it is the expected result. Just thought I would let you know so you’re not thinking that something is going wrong.