1. An apparatus comprising: a division unit configured to divide image data into a plurality of blocks each being composed of a plurality of pixels; a detection unit configured to detect a most frequent color for each of the blocks; a calculation unit configured to calculate an occupancy rate of the most frequent color for each of the blocks; and a generation unit configured to generate data by changing between a block composed of at least a low-resolution pixel and a block composed of low- and high-resolution pixels superimposed with each other, based on the most frequent color occupancy rate.