Custom profile analysis . . .

[Joe_Marques]

I am new to making my own profiles and have some questions. I'm using X-rite Pulse Colorelite(Shoot 5D RAW - C1/Magne profile RAW process - print Epson 4800). I have profiled a few papers and will use my Hahnemuhle Photo Rag 308 (Matte Paper) profile as an example for my questions. When comparing this profile to the generic that I can download from the Hahnemuhle site I do see gamut differences in 3D view of both using Monaco GamutWorks. The primary difference is not in gamut size (they are both very close with probably 95% overlap). The difference is color coverage that varies depending on lightness (L).

The custom profile is noticeably larger in the darker tones (under L=50). At L=50 and above they are much closer but never identical.

So here are my questions:

1) My intuitive expectation was that a custom profile would provide a larger gamut overall - entirely encompassing the gamut of a generic profile. This is not the case in practice. The custom profile has a different gamut that substantially overlaps the generic profile. Is this typical?

2) How should I evaluate a custom profile in print? What am I looking for beyond accurate color - since they both produce very similar prints (I do see color differences)? My inclination is to infer that the larger gamut of the custom profile below L=50 means superior shadow detail and tonality - is that right? What else should I gain from a custom profile?

I just want some expert insight into this so I can calibrate my EXPECTATIONS and understand what custom profiling does and does not do vs. generic.

[Jamie_Roberts]

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1) My intuitive expectation was that a custom profile would provide a larger gamut overall - entirely encompassing the gamut of a generic profile. This is not the case in practice. The custom profile has a different gamut that substantially overlaps the generic profile. Is this typical?

2) How should I evaluate a custom profile in print? What am I looking for beyond accurate color - since they both produce very similar prints (I do see color differences)? My inclination is to infer that the larger gamut of the custom profile below L=50 means superior shadow detail and tonality - is that right? What else should I gain from a custom profile?

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Joe--you have it substantially correct. The first thing I look for in a custom profile is better midtone and shadow detail, as well as smoother tonality and dithering.

But you also see better (more accurate) color rendition, or better rendering intents implementation with a custom profile.

Case in point: on the non-K3 Ultrachrome Epson inks, the generic profiles (even Bill Atkinson's old profiles) all shift deep orange / red / browns into magenta. Quite badly, actually. My custom profiles (made with different software) do not do this.

Another case in point: small gamut differences are quite telling in final results... I use ImagePrint, which comes with a number of "generic" profiles for my 4000. As generic profiles, they're very, very good. If you print from a small gamut space like sRGB and don't have areas where the custom profile will excel, then you may never see a difference.

However, saturated greens and dark blues--typical of aRGB (or ChromeSpace, which I use preferably)--were not being accurately reproduced; the generic profiles just didn't push the printer where it could go in those areas. Again, the custom profile I made for ImagePrint prints those colors wonderfully and predictably.

So while the overall gamut is only marginally larger, perhaps, it is more accurate. And when those colours make a difference, boy do they make a difference!

[Joe_Marques]

Thanks Jamie, appreciate the info.