i1Profiler Profile Settings Sliders Investigation

[digitaldog]

There has been some research that when using the relative colormetric intent, with Adobe's black point compensation turned on, colors are shifted in hue and saturation more than they would, compared to the perceptual rendering intent.

I don't really care. When I say I prefer RelCol 9 times out of ten, this is soft proofing images and doing so with lots of profiles even before Photoshop could even soft proof. IOW, I pick this rendering intent a lot time with lots of actual images and lots of differing profiles (RGB, CMYK and for lots of output devices).

What's important to understand is that profiles are kind of dumb. They only see images as huge piles of solid colors. They don't understand colors in context and treat a super colorful scene just like a black dog on a pile of coal. I could care less about dE values here, I care about how my images look in context when I toggle not only RelCol vs. Perceptual but Saturation too (it can work quite well).

My take is to always leave BPC on. If off, and the profile needs it, it helps tremulously and when the profile doesn't need BPC, it plays no significant role PLUS when BPC is on, I prefer the rendering.

Here's what an ICC profile "see's" if you well. One is RelCol, one is Perceptual. I'm sure one has a closer dE value to something I don't care about in this discussion. Which is better? Until you zoom out and view the entire image and then toggle the intents to select one, it's not too easy to pick a rendering intent correctly for your needs.



Having dE values IS useful, but not as useful as just printing a lot of images with the profile after at least picking a preferred rendering of your image. And if you're going to run images through profiles to evaluate the color quality, the test images are kind of important. If you only want to deal with 16 or less, you need something like the Roman 16's which pile a lot of really useful visual image info into a small group of high quality test images. Print two sets with both rendering intents, or just LOOK at a good soft proof. You'll get a lot of good information this way that no dE report can provide.

[digitaldog]

The optimization process came from ColorMunki technology where one would build a profile with a tiny set of patches (50 initially). I'm stunned at this technology. For Munki profiles it works really well! I recently built a profile for a friend using all the usual i1P tactics: 1789 custom patches, an iSis in dual scan mode, the 2500 patch optimization. This fellow built a profile for the same printer using ColorMunki and 100 patches. Mine was better. But the differences were pretty small and while the dE values might be interesting to us geeks, when the various prints made using both profiles were examined, the differences were small enough that I suspect a pretty significant segment of people viewing the two wouldn't notice the differences.

Optimization on the i1P profile above made tiny but visual (if you looked) differences. As I've said in the past, it's great if you have an iSis or you have a lot of time to scan targets and you are super picky and have a good eye. Otherwise I'll offer it but tell people not to expect big differences.

I'd rather NOT have to resort to this process. I'd rather just measure all the patches, build a profile and be done. I suspect that if a subset of the 2500 gray's were incorporated into the original target, this secondary optimization, even for the ultra picky might be moot. I'm very impressed X-rite has this technology. It wasn't aimed for and doesn't really help the advanced i1P user anywhere like it does the ColorMunki user (or someone with i1P who would do something like build a profile with an initially small set of patches).

As for a Perceptual intent, yes, i1P's are better then the legacy app's. This illustrates what was talked about earlier where such differences in all profile making software product in terms of "do anything you want that you think looks good" with a perceptual intent. Think of it a lot like film stocks from various companies. Is Velvia better, more accurate than Kodachrome or Agfachrome (OK that was an ugly film stock <g>)? They all had their own unique 'looks' which is similar to what we see with Perceptual rendering intents.

[samueljohnchia]

I don't really care. When I say I prefer RelCol 9 times out of ten, this is soft proofing images and doing so with lots of profiles even before Photoshop could even soft proof. IOW, I pick this rendering intent a lot time with lots of actual images and lots of differing profiles (RGB, CMYK and for lots of output devices).

...

Andrew, thank you for your valuable advise. I fully agree that testing on good quality and useful targets as well as real world images would tell a more realistic story than simply looking at the numbers alone.

I also think that BPC is useful, and it renders photographic imagery in a more pleasing manner in the deep shadows.

In my own testing, I noticed that relative colormetric introduces banding into the yellows where perceptual does not. This is irregardless of having BPC on or off. This is only for profiles made by i1Profiler. Have you seen this issue?

[samueljohnchia]

Ah, I figured it out. I don't think anyone else should have this problem. Please ignore my question.

[digitaldog]

This is only for profiles made by i1Profiler. Have you seen this issue?

Only on synthetically created images like a Granger Rainbow. There's areas of banding in many area's, I don't expect to see perfect smoothness.