What is disclosed is a method for compensating for printer characteristics having a tone reproduction curve which is either too rough to be fitted by interpolation or which does not have a simple parametric function. The method comprising first placing a first set of control points on the tone reproduction curve such that each point is representative of the behavior of the curve in the vicinity of that point and fitting a first smoothed curve to the first set of control points. A subset of points belonging to the set of first control points along the first smoothed curve is moved, thereby indicating a desired change in that region of the curve of the original function. A second set of control points is generated from the set of moved first control points and the remaining unmoved first control points and a second smoothed curve is then fitted to the second set of control points. A differential function between the first and second fitted curves is then determined. This difference is added to the original curve to produce a smoothly modified last curve, which retains the original curve's characteristics.