A color display screen displays a calibration color patch and a comparison color patch. The calibration color patch manifests a calibration color of a predetermined intensity, and the comparison color patch manifests a comparison color derived from a user determined input value. The system is controlled by a processor and is responsive to a user's indication of a perceived color match between a calibration color patch and a comparison color patch, to determine a transfer function that enables conversion of a value that generated the comparison color to a value assigned to the calibration color. The processor is further responsive to further perceived color matches of first and second color patches with first and second different intensity calibration color patches, respectively, to determine if first and second transfer functions determined for the first and second comparisons are within a transfer function threshold value of each other. If they are, the transfer functions are averaged and employed to calibrate colors transmitted to an attached color printer. If they are not within the transfer function threshold value, an additional comparison test is made. If the resulting transfer function is not within the threshold value, a default color transfer function is substituted.