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Bauke

[AP/AD] RGB exported to PDF becomes CMYK

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Hello,

 

When I create a RGB document in Designer and export it using one of the following presets, it always gets converted to CMYK, even when explicitly setting its colour space to RGB.

  • PDF/X-1a
  • PDF/X-3
  • PDF/X-4

The PDF settings that kept the RGB profile (regardless of explicitly setting the colour space to RGB) were:

  • PDF (for export)
  • PDF (for web)
  • PDF (for print)
  • PDF (flatten)

Is this a known bug? I could recreate in both AD and AP in 1.5 and 1.6 beta 1.

 

Thanks in advance!

Bauke

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Hi Pruus,

 

I agree about X-1a, but I beg to differ about the others. As I understand it, not only do PDF/X-3 and 4 fully support RGB [1], it's actually contemporary best practice to keep pixel images in RGB until the last step in the process (which would be the RIP of the printer) [2].

 

Best,

Bauke

 

[1] https://en.wikipedia.org/wiki/PDF/X#List_of_the_PDF.2FX_standards

[2] https://indesignsecrets.com/import-rgb-images-indesign-convert-cmyk-export.php

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So Dave,

 

How does one get an RGB image to both hit the PDF as RGB, and, preferably, be a tagged RGB image using the profile embedded in the image? Or, at least tagged with the RGB profile of the AD document?

 

post-255-0-30861800-1495636801_thumb.png

 

The image is a TIFF with Adobe RGB profile. The AD document is CMYK witht he RGB also set to Adobe RGB. It hits the PDF as deviceCMYK. The PDF profile from AD is PDF/X-4

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We preserve RGB images in PDF/X-3 and above, where we can. The main colour space, however, has to be CMYK or Grey, and vector colours are converted to that.

 

 

Hi Dave,

 

Thanks for the answer! I see now that RGB images are being kept RGB while vectors are converted indeed. It seems my tests were poorly made; I only used vectors.

Is the converting of vector colours a technical limitation of your pdf implementation or a deliberate choice?

 

Best,

Bauke

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Is the converting of vector colours a technical limitation of your pdf implementation or a deliberate choice?

 

It's a deliberate choice. One issue is that if we have to rasterise a vector area, we have to pick a colour space in which to do that, and using the target CMYK space of the PDF seems best. If non-rasterised vector colours don't use the same space, they'll look different.

 

 

How does one get an RGB image to both hit the PDF as RGB, and, preferably, be a tagged RGB image using the profile embedded in the image? Or, at least tagged with the RGB profile of the AD document?

 

Did you try your test with the 1.6 beta? I believe there were bugs in 1.5 that were too restrictive about what RGB profiles they would accept. You also need to make sure the image doesn't get rasterised. Other than that it should happen automatically.

 

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Ah, thanks Dave. nope, I wasn't using the 1.6 beta as I had the release running already making stuff.

 

As this post seems to be in the general release bug section, not the beta bug section, it didn't click to try the 1.6 beta.

 

Mike

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