Hi Thibaut, Chris already answered your questions, just to put his statements to a more practical level: - the reason behind you have both "no conversion" and "convert to destination (preserve numbers)" is that you can place a multitude of image types into an InDesign document. I suggested to you to start with your own device CMYK (your printer's color space), because this way you will be very 'close' to your final output, doing edits the most direct way. But there are many other kinds of workflows. Consider agencies, which develop raw ideas into final advertisements for different output channels (medias), like print (sheetfed), print (newspaper), print (banners), web, tablets, etc. All those output channels require a different kind of color output. A very clever approach among agencies is to drop RGB images into Indesign, and let it do the conversion for the final intended output. This way they can use only one version of the key graphics elements, they don't need to make a different (CMYK) version for the different print outputs - Indesign's doing the separation on the fly, at the time of PDF creation. So, there must be a way to turn RGB elements to CMYK, but retain CMYK elements in their original form: this is what "Convert to Destination (Preserve Numbers)" does. On the other hand, there are even more sophisticated workflows around. You can author a PDF file with all the graphics elements stuffed into it in their original color space, and let the conversion done by an advanced color server somewhere down the line. This is how advanced PDF/X-4 workflows achieve outstanding results - and it starts with a "No Conversion" setting in Indesign. - For practical reasons, you should set you working color spaces to the most often used color spaces among your jobs. I guess sRGB for RGB and ISO Coated v2 for CMYK would be a good choice, as most of the RGB data one can encounter nowadays is sRGB, and you already indicated that ISO Coated v2 is your intended output. As Chris said, all the created documents from now on will inherit these color spaces assigned to them. You should also set your default color conversion policies to RGB: "Preserve Embedded Profiles" and CMYK: "Preserve Numbers (Ignore Linked Profiles)". These settings will also be inherieted by new documents. Now, if you place CMYK images into a new document, and you produce a PDF file, the color percentages in the images will stay the same (the separations will be intact) if you choose "No Conversion" or "Convert to Destination (Preserve Numbers). Be aware, that in the former setting, any RGB or Lab elements will be inserted as such into the PDF, which might cause you trouble at the time of RIPping. You can still force Indesign to perform a color conversion, though. By using the "Convert to Destination" setting, you can convert all elements to a designated color space, for example to make a proof on a printer, for which you have an accurate ICC profile. In this case, if you set the Destination color space to your Document Color space ( = the two spaces are the same), then a null conversion is performed, so the resulting CMYK data (numbers, percentages, separations) again identical to the original. Hope this helps. Kind regards, Peter Nagy Colorcom Media Budapest, Hungary