An image processing apparatus having a memory for holding an image aims to improve an image processing speed.The image processing apparatus includes a writing unit, a reading unit, and a reduction unit. The writing unit writes a predetermined number of pieces of pixel data arranged in a predetermined direction in image data in which the pixel data is arranged in a two-dimensional lattice pattern to be distributed over the plurality of memories. The reading unit reads a predetermined number of pieces of pixel data from the plurality of memories. The reduction unit executes processing of smoothing in a predetermined direction onto the read pixel data.