1. An apparatus comprising: a control system implemented in a printing system, wherein the printing system includes a print engine that is operable to apply colorant onto a continuous-form medium, and further includes a radiant dryer that is operable to apply heat to the medium based on a heating power; the control system is operable to direct the print engine to print a plurality of test images onto the medium, and to vary at least one of the heating power and a colorant density for each of the printed test images; the control system is further operable to determine a drying quality for the printed test images, and to calculate an operational range of colorant densities and heating powers for the medium based on the drying quality for the printed test images; the control system is further operable to receive image data captured from a printed test image, and to determine a difference between the image data and reference data for the printed test image; the control system is further operable to determine that the difference between the image data and the reference data indicates burning is present in the medium, and to determine that the printed test image is over-dry subsequent to exiting the radiant dryer based on the difference.