Patent ID: 7495799

Claim:
A method comprising: printing samples on print media with at least first and second marking engines; determining a first lightness value of a solid area of a first sample printed with the first marking engine; determining a second lightness value of a solid area of a second sample printed with the second marking engine; comparing the first and second solid area lightness values to one another; based on the comparison, identifying a lighter marking engine and a darker marking engine; determining lightness value of the print media; determining a critical area coverage of the darker marking engine as being directly proportional to a scaled solid area density which is a result of a division of a difference between the first solid area lightness value and the print media lightness value and a difference between the second solid area lightness value and the print media lightness value: A ⁢ ⁢ C crit = S * 100 ; S = L sad_ ⁢ 1 * - L paper * L sad_ ⁢ 2 * - L paper * , where AC crit is the critical area coverage of the darker marking engine; S is a scaled solid area density; L* sad — 1 is the first solid area lightness value; L* sad — 2 is the second solid area lightness value; and L* paper is the lightness value of the print media; and adjusting tone reproduction curve of the lighter marking engine to substantially match tone reproduction curve of the darker marking engine.