Abstract: A method of generating a stochastic screen for use in printing a halftone containing image on a surface, where the generated stochastic screen comprises an array of threshold values each of which represents a halftone threshold at which pixels are printed at the corresponding location. The method comprises a) entering a first threshold value into the array and b) for a first halftone level, defining a number of threshold values to be entered into the array and, for each threshold value to be placed, for each of a number of candidate locations in the array, computing a distance function between the candidate location and the locations of threshold values already placed into the array, and placing the threshold value into the array at a location for which the distance function is substantially minimized. The process of step b) is then repeated for each subsequent halftone level.

Abstract: A method of characterizing the colour printing characteristics of a colour printer 2 which is arranged in use to receive print commands and data from a computer system 1 coupled to the printer 2 and to print data using a first colour space (CMYK). The computer system 2 comprises an operating system for receiving print data in a second colour space (RGB) from an application residing on the computer system 1, and for passing said print data to a printer driver which converts the print data from the second colour space to the first colour space before passing the print data to the printer.