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Dull text appears on one page, while same color text on other page appears correct

Oct 24, 2013 1:15 PM

Tags: #color_rendering

I have a document that I stamped with a number of text blocks using a third party toolkit (iText). When looking at the stamps on two different pages, the corresponding stamps are appearing in different colors (though their color specifications are the same). For instance the blue "10" in the upper right hand corner of the Incorrect image below is 100% blue, 0% red and green, and the "11" in the upper right hand corner of the Correct image below is ALSO 100% blue, 0% red and green; they're just on different pages.

Incorrect:

incorrect.png

 

Correct:

correct.png

 

I at first thought it might be the 3rd party toolkit, but when I opened it up in Acrobat X Pro and looked at the properties of the text block I saw the following:

 

colors_dont_match.png

 

I can upload the PDF if it helps, I just need a place to upload it.

 

Thanks for any help!

 
Replies
  • Currently Being Moderated
    Oct 25, 2013 10:16 AM   in reply to tomcruise1981

    You can post it for free on Acrobat.com and then share the link.

     
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  • Currently Being Moderated
    Oct 25, 2013 2:12 PM   in reply to tomcruise1981

    Looks like a transparency issue. Reader/Acrobat 11 will probably show it consistently, or you can change the blend space to RGB. (Haven't looked at the PDF, but it sounds like the classic symptoms).

     
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  • Currently Being Moderated
    Oct 28, 2013 7:25 AM   in reply to Test Screen Name

    Yes, I think Test Screen Name is correct. This is related to transparency/rendering/creation. You can find more details (and an explaination from lrosenth) in the iText general forum at:

    http://itext-general.2136553.n4.nabble.com/Color-shift-and-missing-Tra nsparency-Group-td2170709.html

     
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  • Currently Being Moderated
    Oct 28, 2013 12:41 PM   in reply to tomcruise1981

    Ok, try setting the blend space.

     
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  • Currently Being Moderated
    Oct 29, 2013 11:45 AM   in reply to tomcruise1981

    Seems to work as I'd expect, if not as I'd wish.

     

    I'll ignore the text "Here is some rendered..." which is dark red in DeviceRGB.

     

    The text "10" on page 1 and "11" on page 2 are both 100%-0%-0% DeviceRGB.

     

    Page 1 has transparency. Neither page has a blend space. In Acrobat 5 through X the default blend space is DeviceCMYK, so the page is converted from RGB to CMYK and back to RGB, causing darkening. Page 2 has no transparency so it is left alone.

     

    Acrobat 11 (not currently installed for me to test with) should have a default blend space of DeviceRGB.

     

    If I set the blend space as I suggested in reply #6, it works as expected. I set it to Adobe RGB and both "10" and "11" were identical reds. You mention blending mode, no idea what that means, sorry. The other stuff you mention has no impact on transparency blending.

     

    This all comes down to ambiguities in the PDF specification, which we all hope one day will be fixed.

     
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  • Currently Being Moderated
    Oct 29, 2013 4:32 PM   in reply to tomcruise1981

    You have to set the blend colour space for the page. Nothing else will do. No idea if iText does that, but there was a very long article linked earlier which suggested it didn't - did you read that? In Acrobat, use the poorly named Flattener Preview to set the blend space (be sure to choose All Pages). This is under the Print Production tools. The greens and blues become consistent. What they become depends on the colour space you choose.

     
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