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Author Topic: Xrite Color Checker values in Pro Photo RGB  (Read 2512 times)
Ellis Vener
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« on: January 20, 2012, 12:33:23 PM »
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I understand that there will be some, presumably slight, variations between individual batches of 24 patch ColorCheckers, ColorChecker Passports (or similar from other companies) that is the nature of printed materials and inks. But are there ideal reference values I should be looking for the various standard RGB working spaces like sRGB, Adobe RGB (1998), and Pro Photo RGB with a brand new ColorChecker target?
I am trying to technically "perfect" my artwork copying results.

The workflow I use, so far:
I.) Photographing artwork (and full size 24patch CC) in tightly controlled illumination with Canon EOS 1Ds Mark III using the .cr2 format or higher resolution camera (As needed).

II) Importing the raw files into Lightroom 4vBeta and converting to DNG
IIa) Creating a camera calibration profile for the setup using Adobe DNG profile editor, closing Lightroom and then restarting it
IIb) Apply the profile to the photos from the session, and applying the appropriate lens aberration correction.
IIc) using the WB tool on the second or third lightest gray patches.
IId) Exporting in 16 BPC Pro Photo RGB and opening in Photoshop CS5.

III) Edit document in PsCS5 as needed. Mostly this is checking for dust on artwork and/or sensor; applying a Midtone Contrast Enhancement (thank you Mac Holbert!) as a layer*; and then use the subject appropriate PhotoKit Sharpener 2 "Creative Sharpener" and then saving as a layered master file
IIIa) Reimport document into Lightroom 4 and soft-proof for sRGB and Adobe RGB (1998) and if need make a virtual copy and deliver as an 8 BPC TIFF or JPEG in the color Space requested or required by client's needs.

However I know there have to be some target values for the squares in the color Checker, particularly with the gray scale squares. I am not trying to get every square to a specific number as I think that is a fool's errand. My goal is to get the grays neutral as once the middle grays are neutral the mind does a pretty good job of perceiving the other color relationships pretty well, and also if the photos will be mass reproduced I want to make the press operators life as simple as possible.  


*I use Holbert's MTCE instead of Clarity in Lightroom so I can adjust how strongly the effect is applied through opacity adjustments and if needed, masks, based on the content of the image.
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Ellis Vener
http://www.ellisvener.com
Creating photographs for advertising, corporate and industrial clients since 1984.
bjanes
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« Reply #1 on: January 20, 2012, 12:55:01 PM »
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I understand that there will be some, presumably slight, variations between individual batches of 24 patch ColorCheckers, ColorChecker Passports (or similar from other companies) that is the nature of printed materials and inks. But are there ideal reference values I should be looking for the various standard RGB working spaces like sRGB, Adobe RGB (1998), and Pro Photo RGB with a brand new ColorChecker target?
I am trying to technically "perfect" my artwork copying results.

You might take a look at this thread, which covers many of the topics.

Regards,

Bill
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Ellis Vener
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« Reply #2 on: January 20, 2012, 01:12:46 PM »
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Thanks Bill.
Lindbloom's values are from about 6 years ago. I don't know if Xtrite has changed them since then, and Xrite's RGB values are for sRGB only but the LAB values should be useful.

Thank you for that link. 
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Ellis Vener
http://www.ellisvener.com
Creating photographs for advertising, corporate and industrial clients since 1984.
deejjjaaaa
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« Reply #3 on: January 20, 2012, 06:17:59 PM »
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IIc) using the WB tool on the second or third lightest gray patches.
for xrite passport those patches are not neutral - that is why a dedicated WB patch was supplied, may be old pre passport CC is better - but for passport read this for example : http://www.rmimaging.com/information/ColorChecker_Passport_Technical_Report.pdf and it is recommended to overexpose WB patch (but no clipping), just to get better signal to noise.
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Ellis Vener
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« Reply #4 on: January 20, 2012, 06:32:40 PM »
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Although I was skeptical read your post I did find a great deal of useful information in the link to Robin's site that you posted so thank you.
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Ellis Vener
http://www.ellisvener.com
Creating photographs for advertising, corporate and industrial clients since 1984.
deejjjaaaa
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« Reply #5 on: January 20, 2012, 06:55:29 PM »
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Although I was skeptical read your post
why ? that grey patches are not neutral ? or that for WB measurement it is nice to have as much signal to noise ratio and overexpose the WB patch (by 1-2 stops vs spot meter) - not meter off it AS IS ?
« Last Edit: January 20, 2012, 06:59:13 PM by deejjjaaaa » Logged
Ellis Vener
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« Reply #6 on: January 20, 2012, 07:24:03 PM »
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The former- that the gray patches are not neutral. That surprises me.
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Ellis Vener
http://www.ellisvener.com
Creating photographs for advertising, corporate and industrial clients since 1984.
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