Color Cast in printing is a deviation causing neutral colors, such as gray, to acquire an unwanted color tint (like blue or yellow). The root cause is an imbalance in the CMY inks, which must be viewed under a Standard Illuminant like Illuminant D50. For diagnosis, refer to the Neutral Gray area on the reference print; a tint there indicates an imbalance. Failure to evaluate under the correct light disrupts the brain’s Color Constancy mechanism, leading to the mistaken approval of a false color cast.

To correct this, prepress technicians must adjust the color separation curves to balance the amount of CMY in the neutral gray area. For example, if a blue cast is present, Cyan must be reduced, and Yellow and Magenta possibly increased slightly. The final goal is that the CMY and Black (K) combination creates a completely neutral color under standard light. Precise control of the White Point and mid-tone grays ensures all colors in the image are displayed without visual distortion.