There are provided an image processing apparatus which corrects the curvature of a scanning line using image data in image formation, and a control method thereof. When reading out image data by burst transfer from a memory in the line direction of a scanning line on the basis of the read start address of the image data and the burst transfer length, the switching address in the line direction for switching a line of image data is set. The image processing apparatus generates, based on the switching address, the second read start address for reading out image data of the second line, so as to read out image data by burst transfer of at least the first line before line switching and the second line after line switching, in accordance with the set switching address. Image data is read out in accordance with an address generated by the address generator, to form an image in which the curvature of a scanning line is corrected.