If you don’t already know, RGB is model based around light (Red, Green and Blue) which is why this is used for things like web pages, hence backlit screens.
When using images for print based products it is best practice to use the CMYK colour mode. This is made up of the printing inks Cyan, Magenta, Yellow and Black (Black taking the K for ‘Key’ colour). If you leave your artwork as RGB you run the risk of any bright colours being dulled down in the conversion process at the pre press stage in the printers. However if you can convert to CMYK beforehand you then have a better control and visual of what you will get in the final printed material.
Ok so with the technical stuff out of the way, how do you convert an RGB PDF into a CMYK PDF? This can be done in Acrobat Pro itself.
Open the PDF in Acrobat
Choose Tools > Print Production > Convert Colors
- Select the RGB colour space
- Select the FOGRA39 profile (this is a print industry standard)
- Check which pages you would like to convert
Click OK and you’re done!
As you may see, the colours could change slightly or drastically depending on how the artwork was initially set up. If you are happy, you are now have a CMYK PDF. If not you can always go back to the original artwork source and amend the colours to CMYK and adjust at that stage.
I have worked in the print trade since 2000 so getting to be a bit of a dinosaur! The amount of RGB artwork that come through the door is pretty incredible, I do hope this little bit of advice can help a few people and provide an understanding of these colour modes.