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sd5e8a
Inspiring
September 8, 2022
Question

Proper conversion and simulation?

  • September 8, 2022
  • 1 reply
  • 240 views

In the document that I'm planning to print in offset there are some color pages (sRGB), but the rest is in grayscale (sGray).

 

The printer told me that the colors must be converted to Fogra52.

 

When I asked about the gray content, they told me to convert it to Dot Gain 15%. But it sounded more like a recommendation than a rule. I wonder is this a normal practise?

 

I have an impression that they know more about working with colors than with grayscale content.

 

They also told me that I can do the gray-to-gray conversion in Acrobat with the "Preserve Black" option checked.

 

I also don't understand which simulation profile should I rely on when evaluating the gray content: Fogra52 or Dot Gain 15%?

 

I guess that the K channel of Fogra52 will be used, cause that's what this printery is profiled for.

 

Subjectively speaking, the Fogra simulation seems a bit dark to me, but when I switch to the Dot Gain 15% simulation, it looks fine. Now I'm not sure which one of these should I rely on.

 

I'm so confused by all this that I even considered leaving the sGray content as it is. It looks a bit washed out when viewed in CMYK simulation, but maybe this is better than getting too dark prints.

 

What's your opinion on all this?

 

Thanks.

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    1 reply

    D Fosse
    Community Expert
    D FosseCommunity Expert
    Community Expert
    September 8, 2022

    In Photoshop you can convert grayscale images to Black Ink <CMYK profile>. Then you know it will be treated correctly.

     

    In Color Settings > Working Gray, click Load Gray and navigate to the CMYK profile you want, in this case FOGRA52. Once you've done this, it will also be available as a grayscale profile you can convert to.

     

    In InDesign any grayscale content will just go straight to the K channel unmodified. If the numbers already conform by doing this conversion, it will come out right.

     

    sGray will certainly not be right, so leaving them is not a good idea. You won't see this in Photoshop, because all grayscale is fully color managed there, but you will see it when it goes to press.

     

    The dot gain profiles are generic (and in practice outdated). You'll get closer, but not entirely right. Actual dot gain transfer function is not a fixed percentage, but a curve. This curve is built into CMYK profiles.

     

      S
      sd5e8aAuthor
      Inspiring
      September 9, 2022

      In Photoshop you can convert grayscale images to Black Ink <CMYK profile>. Then you know it will be treated correctly.

       

      Thank you, @D Fosse.

       

      Other participants on this forum have mentioned this, but I wasn't sure is that the 'right way' to do things.

       

      I would like to do such conversion in Acrobat (for some reason I can't go back to Indesign now).

       

      So, in Photoshop, I loaded the Black Ink from the required CMYK profile (Load Gray), I saved it as ICC (Save Gray) and I installed it. But it doesn't appear in Acrobat's Color Converter. Is there a way to load it there?

       

      There is another way to do the conversion: Print Production > Edit Object > Select All > Properties > Convert, and it works, but using the Color Converter gives more control and its tidier.

       

      It seems that there's one more way to do this conversion, that is: converting to CMYK with Preserve Black and Promote Gray to CMYK Black checked.

       

      The result will look the same as the previous ones, but now the content will be identified as CMYK and not as Gray (even though it will use the black plate only). This might create some problems, I think.

       

      The dot gain profiles are generic (and in practice outdated). You'll get closer, but not entirely right. Actual dot gain transfer function is not a fixed percentage, but a curve. This curve is built into CMYK profiles.

       

      I think I understand. The CMYK profile already contains info on the dot gain + other characteristics, so there's no need for me to use the Dot Gain % profiles.

       

      They are more 'modest' (sort to speak) and they do not give us a full picture, cause they don't take into account all the characteristics of the press, just the dot gain. That's how I see it, correct me if I'm wrong. Thanks

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