By using different conversion patterns from input gradation values to output gradation values for each coordinate inside a continuous region with a predetermined area, an image processing circuit is for halftoning which approximately expresses a number of gradations which is higher than the number of gradations which are output for each dot is optimized for each type of apparatus while being shared between types of devices where the number of gradations in the output gradation values is different. There is an image processing apparatus where the number of indexes is relatively high in a case which corresponds to a low gradation level which is a halftone level where the number of gradations in the corresponding output gradation values is relatively low.