Four-color process printers generally use gray balance for achieving color balance. Here we describe a novel gray balance control system which uses multivariable state feedback principles. We show that the system performance is greatly improved and the requirements on number of color measurements per calibration initialization are greatly reduced. A synthesis of a state space control model, feedback controller and TRC smoothing techniques are discussed in detail to achieve good prints after gray balance. Experimental results are shown to validate the approach when used for real-time feedback control of color systems.