An image processing apparatus includes: a pipeline processor that inputs image data shifted 1 pixel at a time in a sub-scanning direction; a detector that inputs and holds each pixel of the image data, compares each pixel value of the held plurality of pixels, and detects an edge of a front end or a rear end of an object; a counter that counts a number of pixels that each pixel of the image data shifted in the sub-scanning direction; a distance coefficient determiner that uses a count value of the counter to determine a distance coefficient; a correction value calculator that calculates a correction value; a corrector that adds the correction value of each pixel to the pixel value of each pixel of the image data; and a position where the correction value is added is a position shifted at least N+1 pixels.