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roberte13933108
Known Participant
March 18, 2020
Question

Exporting RGB, CMYK and Grayscale to print pdf

  • March 18, 2020
  • 1 reply
  • 14602 views

I have been asked to start a new thread, so here it is again. I am using ID CC2020 15.0.2, and Windows 10. I am trying to export from ID to a pdf for commercial print on Indigo presses. - RGB color (Adobe RGB profiles embedded), plain K b/w (images scanned from b/w negatives GRAYSCALE with gray gamma 2.2 embedded) and CMYK process colours. None of the ID output settings produce the same result as converting the RGB into CMYK in PS and substituting the new colour files before exporting the whole work with no conversion. This method kept the printed K at the correct density. 

When exporting using the RGB photo files, CMYK process colors, and the GRAYSCALE files, the grayscale is washed out if the export output is 'convert to destination'  It mattered not which PDF-X was selected, or none,  or what destination profile (ISO coated V2 300% ECI) was set, or preserve numbers,  or ignore profiles, or not. The color - both RGB images and CMYK process colour - were converted just fine, but not the b/w K files which were rendered as a shade of grey.  I tried sending a test pdf unconverted which went through the rip converting both RGB and CMYK colour correctly, but the b/w  was washed out K again. Does anyone have a fix for this?

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1 reply

rob day
Community Expert
rob dayCommunity Expert
Community Expert
March 18, 2020

As I mentioned in the other thread InDesign does not have a grayscale color space—a grayscale object’s values get put on the Black plate unchanged, and the Overprint Preview is color managed by the assigned CMYK profile.

 

I think your problem is the Gamma 2.2 profile you are using for the grayscale in Photoshop confilcts with the ISO Coated V2 300% press profile you have assigned in InDesign, and are using as the PDF/X-4’s Output Intent.

 

The solution is to assign or convert the Photoshop grayscale to the Black Ink version of the ISO Coated V2 300% CMYK profile. To do that open Color Settings in Photoshop, from the Gray Working Space dropdown choose the ISO Coated V2 CMYK profile. That will set the Gray Working Space to the Black Ink version of ISO Coated. You can then use Photoshop’s Convert to Profile... to convert your Gamma 2.2 grayscales to the Black Ink ISO Coated profile:

 

Here in Photoshop you can see the difference in preview between Gamma 2.2 (top) and Black Ink ISO Coated

 

 

If I convert the Gamma 2.2 version to Black Ink ISO Coated and place in InDesign with Overprint turned on I get a matching preview. Note that you have to turn on Overprint preview in order to get a Print soft proof.

 

The exported PDF/X-4 with Output Preview on, matches the ID Overprint Preview

 

    R
    roberte13933108Author
    Known Participant
    March 18, 2020

    there is no iso coated v2 300% profile listed under the working space gray drop down in my PS color settings. It is listed under CMYK working space drop down only.

    R
    roberte13933108Author
    Known Participant
    April 7, 2020

    grayscale K image with gray gamma 2.2 profile and adjusted for optimum density and range./

    Convert to CMYK in photoshop...This flow flies in the face of everything I have been told. Am I right to be sceptical?

     

    If you want to increase dynamic range by converting to CMYK, and not get color casts in the print output, the profile you are converting to would matter a great deal—the profile’s black generation would have a significant affect on the output. Typical offset profiles have light to medium black generation, so there will be more CMY relative to black in the separation numbers.

     

    Furthermore you would have to be confident there would be no additional conversions on export or output. You can prevent additional conversions at export by not including a profile with the quadtone, and exporting to Document CMYK from InDesign. But, the only way to assure that there will not be an additional conversion at output would be good communication with the printer.


    Communication. If only. Printers want certainty. They do not like variables. They want it simple. They want the client to decide without any significant advice from them in case it messes up their job.My understanding is that the old school offset rules do not apply to digital printing. At least not all of them. but most printers seem to think it does. Is this a 'thing' or is it just me?

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