There are many books and articles written about the way different color spaces are represented by different devices. This short response will hopefully answer your immediate questions regarding how to get the optimal result from the work you send us.
RGB and CMYK refer to the type of color space that is used to create the image or design. Typically, photographs are in RGB color space while vector artwork is in the CMYK color space. There are many points of view regarding the best color space for your output. While we work with many combinations of images and artwork in different color space, we get the best results when the image we are reproducing stays within the same color space.
Even with each color space there are different profiles that you can use. A very popular profile is sRGB. While the color gamut of sRGB is more limited than Adobe RGB or ProPhoto, sRGB is the most pervasive color space available and is typically the best color space to use if your image will end up on a website. For the best results please be consistent in the color space that you use and let us know which color space you are using so that we can make the proper adjustments on our equipment.
If there are specific colors that you need to be represented in a specific way, providing us a sample image or requesting a proof will yield the best results.
Posted in: Color Graphics