We all believe in the RGB workflow and it generally works fine. Export a PDF from Indesign and you can choose to convert all the placed RGB images to the destination CMYK profile. But how does it handle CMYK images that have a different profile? Answer: it does not convert them by default.
Also, how does Indesign handle the effects of gradients and colours multiplying over the top of your RGB images? Answer: it converts the image but does not consider the effect of the multiplying colours on the final ink weight in the CMYK PDF.
This can be a problem when you are sending PDFs for publication in newspapers and magazines which require a maximum weight of ink for the type of paper they use. For example, newspapers generally have a maximum of 230% – that’s the total percentage densities of the four printing ink colours (Cyan, Magenta, Yellow and Black). Magazines which use higher quality paper can cope with between 260% and 310%. Offset printing on high quality paper can cope with 350%.
An RGB image with a gradient multiplying over the top can result in an over-ink weight CMYK PDF. This can easily happen with transparency effects.
If you send your PDFs to publications using a third party plugin like QuickCut / PageStore or Adsend, you will usually get an error if your PDF is over ink weight. This results in a lot of panic and messing around when the ad is usually overdue for submission! You could let their systems convert your files over to the correct ink weight on the fly, but then you lose control of the quality of the final product.
This AppleScript converts the current selection of objects on an Indesign page into a new 300 dpi rasterised RGB PSD file and replaces the selected objects with that file placed in a picture box. The advantage? Now you can export this page as a CMYK PDF and Indesign will do the conversion correctly. You will have less problems on the press this way.
Last updated April 18, 2017.
Who knows, there could be many other reasons why you would like to turn a group of Indesign objects into a placed PSD. Get back to me to participate in future updates and get notified as they happen.