An image processing apparatus comprises: a resolution compression unit that performs resolution compression by thinning out pixels of a unit block image that has a second size that is larger than a first size; a registration unit that registers the block image generated by the resolution compression unit in a block management table; and an encoding compression unit that performs an encoding compression process on each block image registered by the registration unit; wherein the resolution compression unit determines a compression level for unit block images having the second size and compresses each unit block image having the second size with a compression rate according to the determined compression level, and the registration unit divides the block image compressed according to the determined compression level into block images having the first size and registers the divided block images in the block management table in units of the second size.