An apparatus to obtain ink density data by scanning color measurement strips on a printed sheet has a densitometer mounted on a digitally-driven X,Y positioning mechanism, an optical sensor for detecting the position and orientation of the sheet with respect to the X,Y positioning mechanism, and a numerical computer for transforming the sheet coordinates of the color measurement strips to the X,Y coordinates of the X,Y positioning mechanism. Thus, the numerical computer can automatically position the densitometer to scan the color measurement strips. In a first embodiment, optical sensor arrays determine the position and orientation of the test sheet with respect to the X,Y positioning mechanism. In a second embodiment, the densitometer itself scans the edge portions of the test sheet to determine the position and orientation of the test sheet. The operator has the option of using sheet coordinates of the color measurement strips obtained from non-volatile storage, from a recording medium such as magnetic tape or disk, from direct operator entry from a keyboard, or from the sighting of the measurement strips on the test sheet arbitrarily positioned and oriented with respect to the X,Y positioning mechanism.