GRAY LEVEL TRANSFORMATION CURVE CORRECTING METHOD AND COLOR IMAGE PRINTER

摘要

PPROBLEM TO BE SOLVED: To provide technique for suppressing coloration of black characters etc., by suitably correcting the part of a black area of a gray level transformation curve for transforming input gray level values of image data into output gray level values. PSOLUTION: A test print having a plurality of gray level patterns is printed out. In a relation of test input gray level value and density value derived based upon measured density values of the respective gray level patterns and test input gray level values corresponding to the gray level patterns, a minimum measured density value of a color component having a minimum measured density value at each test input gray level value is specified. Input gray level values of other color components having density values nearly equal to the minimum measured density value are calculated as correction input gray level values. A black area artificial transformation curve is generated from output gray level values obtained from the correction input gray level values based upon the gray level transformation curve and the test input gray level values. The black area artificial transformation curve and gray level transformation curves of areas other than the black area are combined to generate a black area correction gray level transformation curve, and the gray level transformation curve is corrected based upon the black area correction gray level transformation curve. PCOPYRIGHT: (C)2010,JPO&INPIT