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marshallarts

Image conversion during export to CMYK PDF

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I'm working on a book with a lot of colour images.  My document colour setting is CMYK/8, but of course the source images are all in RGB because they originated from a camera.  It is not clear to me when, or if, the images get converted to CMYK colour space as I would hope/expect.  In the "More..." dialog when exporting to PDF, there is a checkbox labelled "Convert image colour spaces", but when I select PDF/X-4 as the PDF type, it gets greyed out but NOT ticked.  So, do the images get converted when they are placed in the document?  If not, do they get converted during the export?  Or do I have to convert them all before I put them into the document?

At the moment I don't have any other software which can handle images in CMYK, so I can't verify what is in the PDF.  I tried opening it in Photoshop Elements, selected "Images" and it extracted one, but then told me it is RGB.  I think that's because Elements doesn't support CMYK, so if it was in that colour space it just converted it back to RGB - catch 22!  Clearly not a valid test.

Can anyone put my mind at rest and assure me that the PDF WILL have all the images in CMYK?  Thanks.

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1 hour ago, marshallarts said:

"Convert image colour spaces",

This is the setting that specifies that images are converted to document color mode. It is misleadingly not chekced for PDF/X1-a, which does convert RGB images to CMYK, while PDF/X-3 and PDFX-4 do not (they can include RGB images which will be converted later by the printer using the embedded color profile).You should place RGB images in your publication rather than CMYK images so that you can produce RGB versions of your book, as well (without dullening its colors).

You can open an exported PDF always in Publisher and check the color mode (but without saving the document)..

You should probably check with the printer if they want to have the PDF delivered in specific export mode, and using specific color profile (if they do, and you need to change the color profile, remember to "Assign" it rather than "Convert", otherwise all your black text will be converted to four-color black, and the operation cannot be undone)..

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Ok thanks for that. My printer has said he wants PDF/X-4, so I will need to see if it's a problem for the images to be RGB. If it is then I guess I have some work to do, converting them all. No problem, all part of the learning curve - this is all new territory for me. I have asked them about what ICC profile to use (if any) but don't have an answer on that yet.

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In case it helps anyone else...

I know all printers are not the same, but I spoke to mine and having RGB images inside a CMYK PDF is apparently no problem for them - their system will do the necessary conversion.  Also, they prefer that I DON'T embed an ICC profile - he suggested it would make very little difference.  We shall see!  I will soon be uploading my big PDF to them, and a proof copy will appear in due course.

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