1. A method for reducing process banding in a color marking device, the method comprising: performing a first measurement of spatial non-uniformity of a color marking device along a first line in a color space which produces a spatial color uniformity when a target primary color is printed alone; generating a first spatial tone reproduction curve from said first measurement; performing a second measurement of spatial non-uniformity of said color marking device along a second line in said color space in a coverage area of a process color which maximally changes a halftone structure of said target primary color; generating a second spatial tone reproduction curve from said second measurement; combining said first and second spatial tone reproduction curves to produce a modified spatial tone reproduction curve; and calibrating said color marking device at a location of said target primary color according to said modified spatial tone reproduction curve.