1. A method for changing a tonal compensation parameter of a printer without resort to calorimetric measurement, said method comprising: instructing the printer to print a test graphic comprised of features that should differ slightly in tone value, each of said test graphics features spanning plural pixels in both width and height; receiving data based on an assessment of the appearance of the test graphic, as actually printed; and by reference to said received data, changing a tonal compensation parameter of the printer; wherein the received data relates to a width dimension of one or more of said features.