RGB or CMYK?
RGB and CMYK are two different methods for generating/viewing colours. RGB files must be converted to CMYK before printing.
What is RGB?
The colours you see on your computer monitor, smartphone, TV, digital cameras, etc. are in RGB (Red, Green, Blue).
What is CMYK?
Commercial printers print with CMYK (Cyan, Magenta, Yellow, blacK), also known as '4 Colour Process'.
You convert from RGB to CMYK (recommended)
Many graphics software programs give you the option to work in either RGB or CMYK colour spaces. An image created in RGB is not going to look the same when it's printed using the CMYK four colour process. That means you should convert your images to CMYK before you pass the file to us. The best way to do that is by creating your document in a CMYK workspace and converting your RGB images to CMYK in Photoshop (ideally using the GRACoL profile) before placing them in your document. All of this should be done BEFORE you make a PDF, unless you are working in software which doesn't support conversion, like MS Word or Apple Pages. Other times it may be a matter of timing or necessity (e.g. you've collected a bunch of tiny logos from Web sites, and the output quality isn't critical for this project). We have set up a system at Fotoprint which scans your entire PDF and converts images to CMYK using the GRACoL profile, which is the profile our equipment is calibrated to.
Or... we will convert from RBG to CMYK
If you are a professional designer, we may assume that an RGB file was provided to us unintentionally, and we will advise you accordingly. For the majority of jobs, however, we will proceed with converting and outputting a proof, but will advise that you see the proof in person to confirm the conversion meets your needs.