1. A method of scanner characterization comprising: generating a set of patch color values in device-independent color space measured from color patches; scanning the color patches with a scanner generating values representing the patch color averages in scanner device-dependent color space; performing a hierarchical subdivision of device-dependent color space into sub-regions, the sub-regions being defined by cutting planes dividing the patch color values perpendicular to principal axes; and generating a color transformation matrix establishing the relationship between the scanner device-dependent color space and the device-independent color space for each sub-region of device-dependent color space using the patch color values and a weighting function for each matrix, each weighting function giving a weight to each patch color value which is a function of the location of the patch color value.