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How to extract Lab color values from a PDF file

New Here ,
Jun 04, 2025 Jun 04, 2025

Hello I need to compare two Lab values in order to be able to calculate the ∂E between the print and the 'original' color value in the PDF.

The first Lab comes from the spectrophotometer but I'd like to be sure that I calculate the Lab value in the PDF correctly. At the moment and in my opin ion the best way to do it - knowing that Acrobat can give you only RGB or CMYK values - I checked the ICC profile or the output intent in the PDF, then I create a file in Photoshop but first in the color settings I set the ICC profile as the working color space and the rendering intent in the Absolute colorimetric. When I have created the file in Photoshop I just insert the CMYK values read from the PDF into the color picker in Photoshop and it gives me the Lab values.

I know that this procedure works fine but I'd like to know if there is a shortest way to get the Lab values froma a PDF.

Thanks.

TOPICS
General troubleshooting , How to , PDF , Print and prepress
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Community Expert ,
Jun 04, 2025 Jun 04, 2025

@Color Specialist your Photoshop method is pretty effective.  For a truly automated approach, you would need to utilize a PDF library (like Adobe PDF Library, Apache PDFBox, or various commercial SDKs) within a script or application. These libraries allow you to parse the PDF's content streams, identify color definitions (CMYK, RGB, Spot Colors), extract the associated ICC profiles (if embedded or referenced), and then perform the color space conversion to Lab programmatically. This would eliminate the need for manual Photoshop intervention but requires coding knowledge.

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New Here ,
Jun 11, 2025 Jun 11, 2025
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Thank you for your reply, I do not have any coding knowledge and fortunately it is not a daily operation so I can keep on doing it manually. I tested the procedure with some 'standard' color profile and it seems to work perfectly. I think that this should be a kind of requested feature fo Acrobat Pro! Just an eyedropper that can show Lab color and can also allow the choice between rendering intents.

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