METHOD FOR PREPARING PICTURE DATA FOR GRAVURE ENGRAVING

摘要

PROBLEM TO BE SOLVED: To provide a method for preparing picture data for a gravure engraving capable of predicting the variation of the picture quality of an output picture previously. SOLUTION: Initialization is performed and the conversion characteristic of a space filter to be used for converting the picture data is selected (s11). The size N of the filter area is decided (s11), the cutoff frequency cf1 of the space filter is obtained based on the N (s12) and the conversion characteristic table of a standard space filter is given arithmetic interpolation corresponding to a spatial frequency area <=cf1 (s13). The second space filter to be used for emphasizing the sharpness of a picture is set similarly (s14, 15). The spatial filter is given over sampling processing (s16) and inverse Fourier tranformation to calculate weight coefficients (s17). The weight coefficients of the first and second space filters are composed (s18) to convert the picture data by an obtained final space filter (s19).