PURPOSE: To display a color picture in an excellent way even with pattern noise such as a mesh point by applying spatial average to a picture signal obtained from a reader to obtain regulation, and applying binary-coding by means of a fixed threshold value when the regulation is large and applying binary-coding by means of a dither method when the regulation is smaller than a prescribed value.
CONSTITUTION: A small memory capacity is enough for a color conversion table by deciding a coefficient aij so that an address subject to coordinate transformation is distributed almost uniformly on a coordinate space to each color, in a color copying machine where a picture is read by plural CCDs and conducting color output by means of a thermal transfer system. Further, the 2nd and 3rd coordinate transforming circuits 49b, 49c are constituted almost the same as the 1st coordinate transformation circuit 49a. The signal subject to coordinate transformation is applied with a averaging processing and a color conversion table is indexed by the averaged signal. Only when the local regulation of a luminance signal is larger than a prescribed value in this table, binary-coding is applied with the fixed threshold value and the dither method is applied in other cases. That is, a beautiful picture display is conducted by using the binary representation in the region where a picture signal fluctuates remarkably and using the dither expression in other regions.
HOSAKA YASUO
MIURA SHIYUUZOU
YAMADA KIYOSHI
