Under color addition

In four-color printing (or more), under color addition (UCA) is a technique for darkening areas of the printed image by adding colored inks. It is meant to achieve the same results as under color removal, but from a different starting position. Under color removal replaces colored inks in selected areas with black ink to achieve a darker appearance, whereas with under color addition, small portions of the three colors are added to these areas instead of, or in addition to, using black ink.

Under color addition

In four-color printing (or more), under color addition (UCA) is a technique for darkening areas of the printed image by adding colored inks. It is meant to achieve the same results as under color removal, but from a different starting position. Under color removal replaces colored inks in selected areas with black ink to achieve a darker appearance, whereas with under color addition, small portions of the three colors are added to these areas instead of, or in addition to, using black ink.