A CMYK profile is a four channel profile that represents points in the CMYK Color-space. CMYK profiles are almost always printer class profiles and are used in conjunction with Inkjet printers, printing presses, and grand format printers. Manufacturers print drivers generally contain CMYK profiles but in most cases the user has no access or control of the profile. In this situation people generally build a custom RGB profile on top of the CMYK output profile. Although not optimal, this process does work well and is typical of most mainstream manufacturers drivers (Epson, Canon for example). Most RIP’s use CMYK profiles as their output profile and do not put an RGB profile in front of the CMYK profile. This is a more pure and accurate rendering of color but may not be visually better (in the case of photography) and requires the purchase of a RIP.