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Author Topic: ColorChecker Passport doesn't do what I expect  (Read 3929 times)

Dynszis

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ColorChecker Passport doesn't do what I expect
« on: March 13, 2014, 11:40:55 am »

Hello all  :)

I recently began experimenting with Imatest Studio, and now purchased an X-Rite ColorChecker. It doesn't work as I expected, and probably my expectations are wrong.

I expected that Imatest Colorcheck would show an error of zero for a picture of the X-Rite ColorChecker if it is color corrected using a profile generated from that very same picture.

It doesn't work that way, apparently. But shouldn't that be the case? What am I missing?

Thanks for any insight, as always.
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digitaldog

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Re: ColorChecker Passport doesn't do what I expect
« Reply #1 on: March 13, 2014, 12:06:46 pm »

It doesn't work as I expected, and probably my expectations are wrong.
I expected that Imatest Colorcheck would show an error of zero for a picture of the X-Rite ColorChecker...
Your expectations are incorrect, IF I saw zero error's I'd suspect the report were pure BS. The question is, what is the worst dE patch, the average, std Dev etc? Are 24 patches enough to tell you anything useful? How does the profile actually work on images when you apply it?
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ErikKaffehr

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Re: ColorChecker Passport doesn't do what I expect
« Reply #2 on: March 13, 2014, 02:00:47 pm »

Hi,

You are missing two things, in my humble opinion:

1) Imatest indicates that your processing is oversaturated. You can reduce saturation in LR or ACD say -20% and you will get much better values

2) The deviations you have are not terribly bad

Personally I prefer Adobe DNG Profile Editor over ColorChecker Passport.

I don't have a good explanation for the oversaturation issue, but some excess saturation is often beneficial for proper viewing on screen and print.

Best regards
Erik


Hello all  :)

I recently began experimenting with Imatest Studio, and now purchased an X-Rite ColorChecker. It doesn't work as I expected, and probably my expectations are wrong.

I expected that Imatest Colorcheck would show an error of zero for a picture of the X-Rite ColorChecker if it is color corrected using a profile generated from that very same picture.

It doesn't work that way, apparently. But shouldn't that be the case? What am I missing?

Thanks for any insight, as always.

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Erik Kaffehr
 

Rhossydd

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Re: ColorChecker Passport doesn't do what I expect
« Reply #3 on: March 13, 2014, 07:06:37 pm »

Maybe an interesting test would be to compare the rendering of files made using Adobe's standard profile, Adobe's custom DNG profile software and X-Rite's Passport.

That the Passport profiles deliver greater saturation is no surprise and has been well reported by visual assessment ever since the software was first released.
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Dynszis

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Re: ColorChecker Passport doesn't do what I expect
« Reply #4 on: March 14, 2014, 01:59:11 pm »

Hello again,

thank you all for the replies.

Erik, I have already presented the best results I could achieve. I may be wrong, but it looks to me like the mean error gets bigger, not smaller, if I dial back the saturation.

Thanks for the recommendation of Adobe DNG Editor. Brilliant!

Rhossydd, I'm sure to try out what you suggest.

At first I understood you as saying that the Passport chart itself is more saturated than other X-Rite charts, but I think (and hope!) you're not saying that :)
« Last Edit: June 22, 2015, 05:40:53 pm by Dynszis »
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Rhossydd

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Re: ColorChecker Passport doesn't do what I expect
« Reply #5 on: March 14, 2014, 02:13:04 pm »

At first I understood you as saying that the Passport chart itself is more saturated than other X-Rite charts, but I think (and hope!) you're not saying that :)
No, all the color checker 24 charts should be the same (they're not exactly the same in reality, but that's a minor issue and a distraction here).

I think the point is that X-Rite have chosen that profiles from their Passport software will deliver more saturated colours than the Adobe standard profiles or the ones created by Adobe DNG editor.

I tried Passport and didn't use it for this reason. Overall I prefer the rendering of profiles generated from the QP card software, but there's not a huge difference between them and the Adobe generated profiles.
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Dynszis

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Re: ColorChecker Passport doesn't do what I expect
« Reply #6 on: March 15, 2014, 09:14:02 am »

Hello Rhossydd,

thanks for the confirmation.

I pilfered Nikon D4 test files off dpreview, after suspecting that Sony's NEX7 is probably not the most ideal reference camera to test the quality of color correction tools.

[Edit: Probably not the most ideal camera, but definitely capable. I just found out that Adobe's DNG Editor gets the NEX's chroma errors lower than Passport under any circumstances.]

I think you are 100% right: Imatest shows the smallest errors for Adobe's DNG Editor, next best is the Adobe standard profile, and the Passport profile is the worst with 117.7% saturation and the highest mean errors.

Cheers :)

« Last Edit: March 15, 2014, 11:34:55 am by Dynszis »
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