PURPOSE: To correct color resolving characteristic with simple structure even when a deviation is in the color resolving characteristic of the color picture reader by providing a correction means which corrects the color resolving characteristic of the picture reader.

CONSTITUTION: The original picture information read out by a CCD color image sensor 21 is turned into an RGB reflection rate chrominance signal by an equivalent neutral lightness conversion part 24. Further, it is converted into lightness color signals L*, a*, and b*, or the like by a 1st color conversion part 25. A blue lightness signal b* which affects on the signal L* and a* refers to a lookup table 27 and is corrected by a factor according to the difference with the standard blue lightness signal. With the correction, the color resolving characteristic is corrected with simple structure even when there is a deviation of the color resolution characteristic of the color picture reader.