<P>PROBLEM TO BE SOLVED: To prepare an original plate for printing which can produce an image with reduced granularity in a brightness channel in a human visual system. <P>SOLUTION: The original plate for printing is prepared by the use of an ink jet printing system. The minimum halftone dot size printable by the ink jet printing system is larger than the size of pixels of a recording grid defined by an addressing capability of a printing apparatus. Poor image quality and granularity caused by a standard error diffusion algorithm in the system can be eliminated by the use of a constraint correlation error diffusion system. One subset is selected from a complete set of all possible combinations of intensity levels for reproducing pixels based on a multilevel halftoning process of a quantized scalar value as at least one function of input pixel values of the corresponding color component pixels. Preferably, the scalar value represents the brightness or ink amount allocations. <P>COPYRIGHT: (C)2004,JPO&NCIPI 
CONSTRAINT CORRELATION FOR COMPUTER TO PLATE INKJET SYSTEM