UCR is a Color Separation technique used when converting colors to the CMYK print space. Its main goal is to reduce the values of the colored inks (Cyan, Magenta, Yellow) in the dark image areas and replace the equivalent density with Black ink. This process is primarily applied in shadows, which contain a mix of all three CMY colors.

By replacing portions of CMY with Black, UCR effectively reduces the total amount of ink used in that area. This reduction in Total Ink Coverage helps prevent issues like prolonged drying times, set-off, and the risk of the thick ink layer cracking during post-press operations, all while preserving the depth of the dark color. UCR settings are typically applied via the ICC Profile.