A method of operating a printhead of an imaging device includes actuating a plurality of ink jets of the printhead to emit drops of ink onto an image receiving surface in accordance with a test pattern. The test pattern includes full pixel density areas and half pixel density areas that alternate in a process direction. Distances in a process direction between drops of the full pixel density areas and drops of the half pixel density areas in transition regions of the test pattern are then measured. The measured process direction distances are then correlated to a graininess level for the printhead.