Thanks for asking me too, but like many others have already answered, there's no need to convert your images to CMYK before going to InDesign. As a matter of fact, it would be far too early to do so, and merely mimicking the old workflow of graphic design before Desktop Publishing became reliable in handling color separation...

InDesign is indeed very well capable of converting RGB color spaces to CMYK, provided with the required conversion profile. And if you're unsure about doing so, then ask your printer to convert them properly within the PDF (and don't complain about the less brilliant print-out...)

You see, it's never too late to convert RGB colors !

Oorspronkelijk geplaatst op Quora: When using InDesign with the intent of exporting to CMYK PDF, do I have to change my jpg images to CMYK, or will that occur automatically upon export?"