An image processing apparatus which sets threshold value matrices for performing screen processing using the threshold value matrices for respective pieces of image data for a plurality of colors according to an output image, the apparatus including: an allocation section which distributes and allocates memories to the respective threshold value matrices used for the respective pieces of the image data for the plurality of colors within a range that a total of memory allocation amounts to the threshold value matrices is equal to or less than a predetermined upper limit size; a setting section which sets the threshold value matrices in sizes according to the respective memory allocation amounts; and a storage section which stores the set plurality of threshold value matrices in respective allocated memory areas.