Gray balance for a printing system of multiple marking engines

A method for calibrating a printing system comprising a plurality of printers, the method comprising:

• designating one of said plurality of printers as a reference printer;
• defining color values in a color space for a target response sought for each of a plurality of printed test patches on a control page, the target response color values for each printed patch corresponding to a neutral gray with a non-zero first colorant value and second and third colorant values, which are both zero;
• through a first iterative process, generating a printed control page with said reference printer, said control page including said test patches, measuring a response of said printed control page, the response including, for each test patch, a first non-zero color colorant value and second and third colorant values, the second and third colorant values of the response for each patch optionally being non-zero, adjusting a tone reproduction curve for said reference printer based on said measured responses to bring the measured second and third colorant values for each patch closer to zero, and repeating said process to approach the target color values of second and third colorant values of zero for the responses sought;
• designating the measured responses of the second and third colorant values of the patches from the reference printer as the target responses sought for a second of said printers;
• through a second iterative process, generating a printed control page with the second of said printers, said control page including a plurality of said test patches, each of which, when measured, has a measured response, adjusting a tone reproduction curve for said second printer based on said measured response of said second printer, and repeating said process to approach the measured response of the second and third colorant values of the reference printer for each of said plurality of test patches.