A method for calibrating a printing process by applying a selected adjustment curve to an image input file to produce an output file. The adjustment curve is derived to match a target tonal response curve having a function value for 0 that is non-zero or has a discontinuity between 0 and 10%. The adjustment curve has a basic part selected from limited options and an intersecting highlight part derived using a 1-dimensional function having input parameters selected from limited options. The adjustment curve has a starting point (X1, Y1), a highlight curve part having a first slope at the starting point and a first intersection with the basic curve part at (X2, Y2). The first slope and first intersection are among the input parameters selected from limited options. The basic curve part has a second slope at a midrange point (X3>X2, Y3>Y2).