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Lloyd Seymour
Currently Being Moderated

Adjust ink limit specifically for Indesign objects

Nov 26, 2012 11:48 PM

Tags: #ink #indesign #coverage #ink_density

Hi

 

With regards to adjusting maximum ink limit / density for print such as Newspaper, there's a lot of info out there advising how to do this in Photoshop, or even how to identify the problem in Indesign or Acrobat, but what if the object being flagged as having too much ink coverage is not a placed item from photoshop but instead objects or text created in Indesign?  How do you correct those, baring in mind there could many of them? It's as if Indesigns export pdf function needs an ink coverage limit like photoshop.

 

Thanks

 
Replies
  • Currently Being Moderated
    Nov 27, 2012 12:17 AM   in reply to Lloyd Seymour

    @Lloyd – that could be done with special PDF workflow software using special "DeviceLink Color Profiles" for color conversion on a case by case basis (e.g. reducing the ink limit on CMY only and preserving the black generation).

     

    For example in the following product:

    http://www.callassoftware.com/callas/doku.php/en:support:knowledge:dlp

     

    http://www.callassoftware.com/callas/doku.php/en:products:pdftoolboxse rver:dladdon:devicelinkprofiles

     

    There is a lot of work in generating a good DeviceLink Profile, so you have to pay a considerable amount of money for that technology. Even if Adobe (sometime in the future) would implement DeviceLink technology for InDesign PDF export, you'd have to pay for the profiles.

     

    And usualy using DeviceLink technology is part of the PDF workflow of a printing company.

     

    Uwe

     
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  • Rob Day
    3,139 posts
    Oct 16, 2007
    Currently Being Moderated
    Nov 27, 2012 8:12 AM   in reply to Lloyd Seymour

    It's as if Indesigns export pdf function needs an ink coverage limit like photoshop.

    There has to be a color conversion for the total ink limit to be enforced—there's nothing stopping you from forcing the black point of a CMYK Photoshop file to 400% and unless there is a conversion to another CMYK space it will stay that way.

     

    I think it would be relatively easy to build a script that would check for CMYK colors that exceed a given limit and convert them to Lab then back to document CMYK, which would enforce the limit.

     
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  • Rob Day
    3,139 posts
    Oct 16, 2007
    Currently Being Moderated
    Nov 27, 2012 9:58 AM   in reply to Lloyd Seymour

    This AppleScript converts any CMYK color that exceeds the document's CMYK profile's total ink limit to Lab than back to CMYK. The conversion enforces the limit.

     

    http://www.zenodesign.com/forum/CheckInk.zip

     

     

    tell application "Adobe InDesign CS6"

        tell document 1

            --get the total ink allowed by the document's CMYK profile

            try

                set k to make new color with properties {name:"MAXBLACKLAB", space:LAB, color value:{0, 0, 0}}

            end try

            set space of k to CMYK

            set {a, b, c, d} to color value of k

            set inkmax to a + b + c + d as integer

            delete k

           

            --check the total ink of all document colors

            repeat with x from 1 to count of every color

                if space of color x is CMYK then

                    set {a, b, c, d} to color value of color x

                    set ti to a + b + c + d as real

                    if ti is greater than inkmax then

                        try

                            --convert the color to lab and back to CMYK

                            set space of color x to LAB

                            set space of color x to CMYK

                        end try

                    end if

                end if

            end repeat

            display dialog "Total Ink: " & inkmax

        end tell

    end tell

     
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  • Rob Day
    3,139 posts
    Oct 16, 2007
    Currently Being Moderated
    Nov 27, 2012 5:10 PM   in reply to Lloyd Seymour

    There has to be a conversion for total ink to be enforced. Assuming the document has the correct CMYK press profile assigned I can get the profile's total ink max by converting Lab 0|0|0 (absolute black) to CMYK. So US SWOP Coated Lab black converts to 75|68|67|90 (300%), while US Sheetfed Coated allows 350% and black converts to 95|85|85|85. Once I have the document profile's total ink, I can test for colors that exceed it.

     

    When I convert to Lab the appearance of the color doesn't change and when I convert back to CMYK the Lab color is forced into the profile's ink limit.

     

    My script skips the registration color, which can't be altered.

     
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  • Rob Day
    3,139 posts
    Oct 16, 2007
    Currently Being Moderated
    Nov 27, 2012 5:17 PM   in reply to Lloyd Seymour

    One other note, you can test the conversions in Photoshop—fill a CMYK doc with 100|100|100|100, change its mode to Lab and then back to CMYK and the resulting values will depend on the assigned profile.

     

    If you try it on a swatch in ID it doesn't work, at least for me the swatch remembers its original 100|100|100|100 CMYK numbers. I think that's a bug with the ID GUI. Making the conversions via scripting works correctly.

     
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