Profile Verification & Optimization

Two of the new features of i1 Profiler are the ColorChecker Proof profile verification option and Printer Profile Optimization. We’ll start with ColorChecker Proof. The software comes with a new version of the classic 24 patch Munsell ColorChecker but this one has a twist, it has holes in it.

The idea is that you click on the ColorChecker Proof workflow in the software and then drag and drop one of the profiles you’ve made onto the ColorChecker page icon. There is a check box to show which patches are out of gamut and so not expected to be matched on the printer. You then print the ColorChecker image and then get your ColorChecker Proof target and lay it over the print out. You’ll see the printed colours through the holes in the target and be able to evaluate the accuracy of the profile.

The main problems I have with this approach is that it obviously depends a lot on the light source you are viewing the print and the target under but also assessing areas of flat colour often tells you less about the accuracy of a profile than viewing a photographic image, with a wider range of tones and real world imagery we are familiar with such as faces, that our visual system has evolved to evaluate. So whilst I think the ColorChecker Proof is a useful tool I wouldn’t use it in isolation from conventional test images.

Once you have tested a profile you may choose to access the other new feature we’re talking about today, Profile Optimization. The Profile Optimization workflow takes an existing profile and analyses which areas might need a bit of improvement and generates a new set of patches to output and measure. Patches can be generated from images or spot colour libraries as well.

The technology is based on that in the ColorMunki software. The ColorMunki software only produces an initial 50 patch set so I can see the need for generating an additional second set. However, if you start by building an i1 Profiler profile with maybe 1000 or more patches there are unlikely to be many gaps that need filling. When I’ve tested Profile Optimization with RGB printer profiles I’ve never been able to see a visible difference in the final prints between and an optimized and un-optimized profile. There may well be small measurable differences in some colours but if the differences are not visible to the naked eye then it’s debatable if the procedure is worthwhile.

With CMYK printer profile you do sometimes get a small visual improvement and a larger measured improvement in Delta E values, but the improvement isn’t large in either case. I’ll need more time to assess this feature as I begin to use the software more in the field on a wider range of printers and technologies. However, I also find it curious that you can generate up to 6000 new patches and it will always generate the number you set. It never gives any feedback saying the profile is OK and can’t be improved or that only X number of patches are needed to make some improvement. It just generates the number of patches you ask it to. The level of improvement achieved is never quantified in any way either, so I’ve yet to be convinced but time will tell.

The other related feature to the ColorChecker Proof and Profile Optimization workflows is the Printer QA workflow, but we’ll tackle that next time when we talk about CMYK printer profiling.