When you do making graphic design quotes, you will have more control over the appearance of your printed piece if you convert all of the images file format from RGB to CMYK before sending them to the printing services. When a graphic designer receive RGB images, they do a standard-value conversion to CMYK, which may not be perfectly to your liking. If you want to be happy, take the time to prepare your file properly. The printing services cannot be responsible for sub-par results if you furnish low-res images or RGB images.

Be aware that it is possible to make colors in RGB that you can't make with CMYK. They are said to be "out of the CMYK color gamut". What happens is that the translator just gets as close as possible to the appearance of the original and that's as good as it can be. It's something that everyone in the industry puts up with.

So it's best to select any colors you use for fonts or other design elements in your layout using CMYK definitions instead of RGB. Please see the RGB - CMYK Information page for important instructions on getting the results you want.

You most likely won't notice this kind of color shift in a color photograph.

It is more likely to happen if you pick a very rich, vibrant color for a background or some other element of your layout. It probably won't look bad, it just won't look exactly the same. But it may not be noticeable at all either. In any event it will look spectacular compared to a piece printed on an inkjet printer.

Color photos don’t suffer much from CMYK translation (cmyk conversion)