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Author Topic: Camera Calibration for Copy Work  (Read 9636 times)

RogerEle

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Re: Camera Calibration for Copy Work
« Reply #40 on: July 23, 2013, 02:46:18 PM »

Roger, it looks like those files are not publicly accessible.

Works now, Thanks!
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Iliah

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Re: Camera Calibration for Copy Work
« Reply #41 on: July 23, 2013, 03:11:52 PM »

The shot at your http://www.luminous-landscape.com/forum/index.php?topic=80491.msg649791#msg649791 is more suitable for profiling as the neutrality curve on it is the least bumpy. However it is really necessary to keep target sterile clean.
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Ellis Vener

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Re: Camera Calibration for Copy Work
« Reply #42 on: August 01, 2013, 11:18:30 AM »

Are you using Lightroom or Adobe Camera Raw? try the attached ColorPassport generated  profile: even if you do not use DNG as your archiving format for raw files the profile should work in Lightroom 4 and 5 and ACR.
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Ellis Vener
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Creating photographs for advertising, corporate and industrial clients since 1984.

bjanes

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Re: Camera Calibration for Copy Work
« Reply #43 on: August 01, 2013, 12:45:23 PM »

The idea is to profile for light. My setup includes Rosco #1991 or #1995, CTB, pola filter, and a 50% magenta filter on the halogen lights. This way I have full spectrum and equal exposure for all raw channels.

I seriously suggest looking at ColorChecker SG target for profiling, setting the exposure from SpyderCUBE or similar self-made, and having a flat grey surface for both profiling and repro work.

Iliah has made some excellent suggestions. Placing the CTB (and magenta filter, if used) over the light source rather than the lens makes sense since one does not need optical grade filters, and composing and focusing would be easier since the light loss from the filters does not occur in the camera optical pathway. Using ICC profiles made with the ColorChecker SG would obviate the use of LR/ACR for rendering, but one could use Capture One or Rawtherapee.

Bill
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Iliah

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Re: Camera Calibration for Copy Work
« Reply #44 on: August 03, 2013, 11:13:42 AM »

Dear Bill,

SG contains a set of patches that are very close to CC24 ("24 patches from original ColorChecker", "the corresponding patches are laid out on the SG chart in the same configuration as in the standard ColorChecker"). If one wants to be very accurate he can replace the Passport spectral measurements contained in X-Rite profiler for ACR/LR with the respective values from SG.

Now, if "classic" part of SG is used in X-Rite profiler, and the error is computed using all other SG patches one can evaluate the accuracy of profile in a more reasonable way.
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BartvanderWolf

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Re: Camera Calibration for Copy Work
« Reply #45 on: August 03, 2013, 11:44:05 AM »

SG contains a set of patches that are very close to CC24 ("24 patches from original ColorChecker", "the corresponding patches are laid out on the SG chart in the same configuration as in the standard ColorChecker").

Hi Iliah,

Yes, but they are different enough to not mix the different chart patches in an evaluation.

Cheers,
Bart
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== If you do what you did, you'll get what you got. ==

Iliah

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Re: Camera Calibration for Copy Work
« Reply #46 on: August 03, 2013, 12:39:14 PM »

Hi Iliah,

Yes, but they are different enough to not mix the different chart patches in an evaluation.

Cheers,
Bart

Dear Bart,

Can you please explain?
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BartvanderWolf

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Re: Camera Calibration for Copy Work
« Reply #47 on: August 03, 2013, 02:16:48 PM »

Dear Bart,

Can you please explain?

Hi Iliah,

See ColorChecker charts formats where it is explained.

ColorChecker Digital SG (NOT COMPATIBLE)
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24 of the chart patches have colors similar to the original ColorChecker and are laid out in the same configuration.
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However, because of its Semi-Gloss finish, the SG in the chart name, the chart colors are not the same as in the other ColorCheckers (see more info below); thus, you should NOT USE the data in this page for the ColorChecker patches of this chart

Hope that helps to explain.

Cheers,
Bart
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Iliah

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Re: Camera Calibration for Copy Work
« Reply #48 on: August 03, 2013, 02:45:23 PM »

Dear Bart,

But I specifically mentioned "If one wants to be very accurate he can replace the Passport spectral measurements contained in X-Rite profiler for ACR/LR with the respective values from SG."
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BartvanderWolf

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Re: Camera Calibration for Copy Work
« Reply #49 on: August 03, 2013, 03:42:23 PM »

Dear Bart,

But I specifically mentioned "If one wants to be very accurate he can replace the Passport spectral measurements contained in X-Rite profiler for ACR/LR with the respective values from SG."

Hi Iliah,

Then I misunderstood. Good to have it clarified, they have to be replaced. The CC24/Passport and CCSG patches have different specific values, not simply to be used at will.

Cheers,
Bart
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