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Timur Born
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Bug? Working Space color conversion hardcoded in images

Wed Mar 15, 2017 9:38 am

I noticed this behavior before in the Xchange printer driver, but since it's more complex there I post my easier to reproduce/follow observations on extracted images here.

When PDF Tools extracts images from a PDF file it seems to hardcode the Working Space color conversion into the output image files. What this means is that when I set up a large gamut display color profile for my Dell U3014 in Windows color management settings then the output image is converted to supposedly "sRGB" by PDF Tools (decreased saturation and slight green-shift). This is not just inserted as a profile into the image file, but is hardcoded into its colors (aka colors are converted and output as different values).

Once I switch my display profile in Windows' color management to sRGB (or just delete it, which does the same) PDF Tools outputs the image file with original color values.

Extracted with wide gamut display profile in Windows' color management:

Image

Extracted with no display profile (=sRGB) in Windows' color management:

Image
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PDF Tools Color Profile.7z
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Tracker Supp-Stefan
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Re: Bug? Working Space color conversion hardcoded in images

Wed Mar 15, 2017 4:34 pm

Hello Timur,

Thanks for the report. Passing it along to the people working on PDF Tools for investigation.

Regards,
Stefan
 
Timur Born
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Re: Bug? Working Space color conversion hardcoded in images

Wed Mar 15, 2017 6:43 pm

It's worth mentioning again that this sort of also happens with the XChange printer driver. So if you find the culprit, you might also want to take a look at how XChange handles this.
 
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Re: Bug? Working Space color conversion hardcoded in images

Wed Mar 15, 2017 6:46 pm

Hi Timur.

We will investigate your case, there might be some problem. In most cases images must be converted when extracted from pdf because in pdf images can be stored in different color-spaces(most of them are special for pdf/postscript format only), not only in simple rgb. In new version of PDF-Tools you will be able to use one workaround - in the Preferences we will add the "Color Management" tab and there would be possible to choose WorkingSpace=sRGB to avoid unwanted color transformations in your case.

Best
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Vasyl Yaremyn
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Vasyl-Tracker Dev Team
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Re: Bug? Working Space color conversion hardcoded in images

Wed Mar 15, 2017 7:43 pm

It's worth mentioning again that this sort of also happens with the XChange printer driver. So if you find the culprit, you might also want to take a look at how XChange handles this.

Please details - how to reproduce the issue?
Vasyl Yaremyn
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Please archive any files posted to a ZIP, 7z or RAR file or they will be removed and not posted.
 
Timur Born
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Re: Bug? Working Space color conversion hardcoded in images

Thu Mar 16, 2017 10:21 am

The XChange printer driver thing is more complex and likely not an issue of hardcoded colors but of "wrong" color profiles being embedded. I will open another thread for that later, but suffice to say that Editor displays XChange created files in different colors than the original file. One reason being that I also need to wait for Editor to fix its own color management first for better comparisons (transparency/non Cleartype pages vs. non-transparency/Cleartype pages).

I might also have to pay for a month of Acrobat just for comparison of the printer stuff. I will also have another look at how Acrobat extracts images, but from earlier tests I mean to remember that only PDF Tools hardcoded different colors into the extracted images, while Acrobat did not.

So for this thread just forget about my XChange remark and just concentrate on colors for extracted images. ;)
 
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Re: Bug? Working Space color conversion hardcoded in images

Thu Mar 16, 2017 10:36 am

Hi Timur,

We will get Extraction through tools sorted for the next build as Vasyl said, and yes please do start a separate thread for the drivers.

Regards,
Stefan

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