RGB type to CMYK

[FINFAN]

I have a file that was sent from the customer with RGB type. We did not catch this and our rip is not set to convert anything. I assumed all conversion should come from Indesign CS2. The PDF created from rip engine did not have all the type converted to CMYK. Some did and some didn't. I have the manufacturer of our rip system looking into this to see if rip can convert or if this needs to happen in native program. The customer states that they were under the impression that Indesign does this. If anybody has ran into this problem and knows a fix just in case this is missed again. Is there a setting in Indesign that we can use, maybe a preference? Any HELP would be appreciated. Thanx FINFAN

 

[apepp]

...using rgb in a page layout program can be advantageous when dealing rgb images in a color managed workflow, in that images can be multi-purposed for varying print methods...

...this is all very well, but the color management needs to be set up correctly along the production workflow to have benefit...

...when exporting pdf from indesign the only way of getting rgb to cmyk is by "convert to destination" or "convert to destination, preserve color numbers" and selecting an appropriate output profile...

...it gets more confusing whether images are tagged with profiles or not, in which case the source profile will be the document profile of indesign (or your rgb working color space)...

...native rgb indesign elements will take the document profile (or your rgb working color space) as the source...

...so whatever the destination profile is on output to pdf (or postcript), you will get different color values using different output profiles...

...rendering intent also plays a part in the conversion from rgb to cmyk...

...if you have "no color conversion" set in the output options, then RGB is preserved, unless I believe correctly it interacts with transparency, in which case the cmyk blend space is used (edit > transparency blend space)...

...to preserve rgb here would mean changing the blend space mode to rgb...

...so all in all, if a customer wants to make rgb colors for text or other vector elements, they will have to made aware that it can be a roulette as to what colors end up on printed paper...

...now, any "designer for print" will generally avoid such RGB use for text or vector elements, wherever possible...

Andrew

 

[apepp]

...forgot to add that the above really applies to PDF 1.3 (Acrobat 4)...

...it is worth noting that a page with RGB transparency will effect ALL other RGB elements on that page (whether they have transparency or not) when exported to 1.3 (Acrobat 4) with a document blend space of CMYK, the result is a CMYK page...

...higher versions retain transparency so the above statement for:

>>> if you have "no color conversion" set in the output options, then RGB is preserved, unless I believe correctly it interacts with transparency, in which case the cmyk blend space is used (edit > transparency blend space) <<<

...the above statement is rendered differently to PDF 1.4 or higher, in that native RGB elements that have transparency are preserved as RGB in the PDF...

Andrew

 

[apepp]

...also, if working with PDF 1.4 or higher requires a RIP that supports flattening...

...or a RIP that supports APPE (PDF print engine), which is far better, although not fully supported by RIP vendors if problems arise, which is true of Heidelberg UK at least, who do supply it with Prinergy but support is minimal, and will likely tell you to try the CPSI interpreter instead (if not already)...

...sorry, beginning to go off topic a bit now...

Andrew

 

[jdguru]

You can convert PDFs from RGB to CMYK thru Distiller. Try this:
Open PDF and go to File >Save As (Select Format as EPS) and then click on Settings; Click on Output (and select Colour as Composite and then select Printer Profile as Printer/Postscript Color Management).

Click OK (Enter) and OK again.

Save this EPS in IN folder direct and you will get cmyk pdf from Out folder.

Let me know if you need any further help on this.

jdguru