To provide an image correcting method not damaging the quality of a character or segment image even with respect to a segment shape rounded at its terminal or a segment shape changed from a straight line to a curved line.

The segment shape of the boundary part of the black and white dot regions of image data developed in a bit map state is confirmed and the feature of the segment shape confirmed with respect to each dot becoming an object is replaced with code data of a plurality of bits and the image data is corrected on the basis of the code data when correction is necessary. In this image correcting method, when the noticeable pixel Z(101) of a straight line part is detected, it is detected whether input image data at specific places separated from the noticeable pixel Z, that is, reference pixels A-D (102-105) are black or white, in other words, there are image data at the same time along with the detection of conventional inclination and position data and, on the basis of both results, correction data is determined.