Patent ID: 7697151

Claim:
An automatic method for controlling image consistency in an image rendering system that includes marking engines, the method comprising: analyzing input data for a print job, comprising: determining a first input area coverage for a first sheet to be printed with a first marking engine; and determining a second input area coverage for a second sheet to be printed with a second marking engine; comparing the first and second input area coverages to a prespecified area coverage threshold; printing the first sheet of the print job on a first print media with the first marking engine; printing the second sheet of the print job on a second print media with the second marking engine; if both first and second coverage areas were greater than the prespecified area coverage threshold in conjunction with the comparing: measuring light reflected from the first sheet to produce first print density data associated with the first marking engine and light reflected from the second sheet to produce second print density data associated with the second marking engine; identifying a density inconsistency between the first and second marking engines by calculating a first average gray level for the first sheet based at least in part on the first print density data, calculating a second average gray level for the second sheet based at least in part on the second print density data, and determining a first relative density error for the first marking engine and a second relative density error for the second marking engine based at least in part on the corresponding first and second average gray levels; and adjusting at least one parameter of at least one of the first and the second marking engine to improve image consistency between the first and second marking engines based at least in part on the corresponding first and second relative density error.