TWO COLOR PRINTING DATA PREPARING METHOD

PROBLEM TO BE SOLVED: To provide a two color printing data preparing method for preparing two color printing data from four color printing data by simple work or automatically with short work time without damaging gradations and without needing skill. SOLUTION: The data preparing method includes: finding a color to be reproduced to be the darkest color according to the characteristic of input image data (S1); finding a color to be reproduced to be the darkest color in two color printing according to the characteristic of the two color printing; determining a lightness conversion function for linearly converting lightness of the darkest color of input data into the darkest lightness of two color printing from the darkest color of the input image data and the darkest color of two color printing (S3); converting the input image data into a colorimetric value, further converting the input image data into coordinate values of CIELAB, converting L* of obtained CIELAB into L*' according to the lightness conversion function, and searching colors to reproduce a* and the obtained L*' in obtained CIELAB coordinates from colors of two color printing (S6). COPYRIGHT: (C)2008,JPO&INPIT