1. A method comprising: forming a plurality of test patches, said test patches being formed by using an imaging machine, each of said test patches being associated with a respective one of a plurality of initial input color values, said test patches including a plurality of varied-input test patches and at least one group of first equivalent-input test patches; measuring a respective output color value of each of the test patches; generating at least one first mathematical relationship based on the output color values of the at least one group of first equivalent-input test patches; calculating a plurality of adjusted input color values for respective ones of the varied-input test patches, each said adjusted input color value being calculated based upon said generated at least one first mathematical relationship; computing a second mathematical relationship between the adjusted input color values and the output color values; and calibrating the imaging machine by using the second mathematical relationship.