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Author Topic: Color Management commentary invited...  (Read 125 times)

RTS

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Color Management commentary invited...
« on: April 06, 2019, 05:30:03 pm »
Hello,
I am now well into the layout phase of a large project — a book containing upwards of 300-400 photographs, and looking for profile setups to control colour output for print. Using many sources, I noticed that certain photos were being over clipped when converting to sRGB where the blues were suffering horribly, gaining a red hue inside the blue.

Stepping back, I decided to reprocess some of the worst-Color-clipped images using this series of steps: This was copied from photo.stackexchange.com:

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It is very likely that your monitor cannot support the full AdobeRGB gamut. The best way to convert an image from one color space to another with minimum changes in color reproduction is by following the below process:

Having set your workflow's color management to AdobeRGB (Photoshop, Lightroom, etc)
Having your monitor profile set in AdobeRGB as well (for premium monitors with good coverage of AdobeRGB color space)

Process the photo
Convert to sRGB
Change monitor profile to sRGB
Assign Profile to AdobeRGB (that's odd but I explain below why)
Convert again to sRGB

That process may look strange at first but it's the best method I found out -the hard way by myself after a lot of efforts!-. Explanation: When you convert from AdobeRGB to sRGB in Photoshop (or other software) the image may still look the same inside the program but you will have the wrong profile loaded in your monitor; if you change the profile of the monitor (to the converted one) is similar like assigning profile in photoshop so you will need to "offset" that shift with reverse "Assign Profile" (these are steps 5 & 6). If you do the above process you will have (almost) the same image: sRGB image with the monitor profile set in sRGB AND AdobeRGB image with the monitor profile set in AdobeRGB.
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It works. It restores the colours, especially the blues to a more natural state, in Scribus. There seems to be some discussion that this image processsing method may not be properly processing the images for print output.

Please, I am looking for color management experts to weigh in on the process described above.

Thanks from Montreal
RT Simon

utnik

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Re: Color Management commentary invited...
« Reply #1 on: April 07, 2019, 02:17:58 am »
hi simon

your procedure sounds a bit strange.
  • how do you convert your images? (if you just clip the color space from adobeRGB to sRGB you'll lose something on the green side and a little bit in the yellow-orange-red range. but just clipping (absolute colorimetric conversion) is almost never a good idea for images.
  • for a reliable color management you need a calibrated (or at least optically adjusted) monitor – not just a profile of your choice.
  • the printer you chose for your book will tell you what output profile you should use. for a simulation of the printed book on screen, you need to select the same profile.
utnik