It’s Best If You do the RGB-to-CMYK Conversion of Your Images
You will have more control over the appearance of your printed piece if you convert all of the images from RGB to CMYK before sending them to us. When we receive RGB images, we do a standard-value conversion to CMYK, which may not be perfectly to your liking. We want you to be happy, so please, take the time to prepare your file properly. We cannot be responsible for sub-par results if you furnish your images in RGB. Even though monitors always use RGB to display colours, the colours you see on your monitor will more closely match the final printed piece if you are viewing them in the CMYK colour space.
Be aware that it is possible to see colours in RGB that you can’t make with CMYK.
They are said to be “out of the CMYK colour gamut”. What happens is that the RGB-to-CMYK 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 colours you use for fonts or other design elements in your layout using CMYK definitions instead of RGB. That way, you will have a better idea of how they will appear in your printed piece. Here’s a common example: many programs translate the 100% Blue in RGB into a somewhat purple-looking colour in CMYK. We recommend a CMYK value of 100-65-0-0 to get a nice clean blue. Working in the CMYK colour space allows you to select the CMYK recipe, or “screen build”, that gives you the results you want.
Here are some examples of how various RGB colours convert to CMYK:
You most likely won’t notice this kind of colour shift in a colour photograph.
It is more likely to happen if you pick a very rich, vibrant colour 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.