Black Printer, UCR and UCA - Gray Component Replacement

Theoretical considerations on the black printer include use of linear color reproduction models which consist of Demichel relations and Neugebauer equations. Gray-component replacement can be defined clearly by a combination of black printer, under-color removal, and under-color addition, as three elements. Analytical expression of necessary operation is given as a form: (a1-ak)/(1-ak) by good approximation, where a1 is a dot area of any color component and ak is a dot area of black ink. As seen in this relation, the numerator shows UCR and the denominator indicates UCA after the introduction of black printer ak. the introduction of black printer ak.