Role of sensor in color rendering?

Started 3 months ago | Discussions thread
OP lélé Contributing Member • Posts: 595
Re: Role of sensor in color rendering?

Iliah Borg wrote:

lélé wrote:

From a practical perspective, I'm struggling to create color profiles with 'pleasant skin tones' for my Sony a7R IV and my former Sony a7 III.

I have also downloaded samples taken with Canon cameras. I have created a color profile from the Canon EOS R DPReview studio scene and Lumariver. I know that their CC24 is (at least) from 2013, so it may have faded. I also don't know the exact illuminant they use. But the idea behind was to create a 'neutral' profile, with no subjective adjustment except the tone curve.
I carrefully inspected the Canon EOS R samples using the created profile and did not notice the issues with skin tones.

Have you done the same for your Sony a7R IV and Sony a7 III ?

If the results are not to your liking, have you asked Lumariver technical support to help?

Yes, but as for the Sony a7 III since I sold it recently I only have color Passport Photo target shots to work with. Not enough skin tones patches to do anything good...

I'll try to email Anders Torger (developper of Lumariver); he was very helpful on other topics. But I don't thinks Lumariver is what causes the problem.
It's the same with Lightroom built-in profiles (at least Adobe Standard, Adabe Portrait, Adobe Camera Standard and Adobe Camera Portrait, for the ones I tried).
It's the same with DxO Photo Lab built-in profiles.

Lumariver + ColorChecker Digital SG (so several skin tones patches to work with) + profile with LUT is actually what attenuates the more the issue. But it can be seen from the LUT optimization table  that light skin tones patches (especially F2 and D8, which is signficantly off compared to the others) lean toward magenta, while darker patches are okay or slightly lean towards green. So I have to allow 'sharp bends' in the LUT (playing with 'min. chromacity distance' and 'worst compresion' settings), because colors that are pretty similar have different shift. The result looks better, but not perfect and this may cause some posterization. Especially if I add some suvbjective adjustements on top...

Of course, the chart may no reflect actual skins reflective spectra. There might be some errors in some patches (I don't have a spectrophotometer to check). There might be some operator error (it's a difficult target to shoot due to glare and I struggled at the beginning). But what Lumariver tells from the target shot is in line with what I noticed before I started making profiles...

 lélé's gear list:lélé's gear list
Nikon D300 Sony a7R IV Canon TS-E 17mm f/4L Nikon AF-S DX Nikkor 17-55mm f/2.8G ED-IF Fujifilm XF 35mm F1.4 R +13 more
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