Patent ID: 8488893

Claim:
An image compression apparatus comprising: an image storing unit configured to store first image data; a conversion unit configured to acquire, from the image storing unit, pixel data thinned out to be of a second resolution which is 1/(2^T) times a first resolution of the first image data (T=0, 1, 2, . . . N), and output the acquired pixel data as second image data; a generation unit configured to divide the second image data into blocks of 2 by 2 pixels, and generate complementary information based on an arrangement pattern of pixel values in each of the divided blocks, wherein the complementary information enables restoration of the second image data by combining the complementary information with a third image whose third resolution is ½ times the second resolution of the second image data, and wherein the generation unit generates the complementary information with respect to each of the second image data whose second resolutions are 1/(2^T) times the first resolution (T=0, 1, 2, . . . , N−1); a first compression unit configured to generate first compressed data by compressing, employing a first compression method, the second image data whose resolution is 1/(2^M) times the first resolution (M<N); a second compression unit configured to generate second compressed data by compressing, employing a second compression method, the second image data whose resolution is 1/(2^N) times the first resolution; a code storing unit configured to store the generated complementary information, the first compressed data, and the second compressed data; and a control unit configured to determine whether to cause the code storing unit to output a combination of the first compressed data and the complementary information generated with respect to each of the second image data whose second resolutions are 1/(2^T) times the first resolution (T=0, 1, 2, . . . , M−1), or output a combination of the second compressed data and the complementary information generated with respect to each of the second image data whose second resolutions are 1/(2^T) times the first resolution (T=0, 1, 2, . . . , N−1), based on at least one of a data size of the complementary information for each resolution, a data size of the first compressed data, and a data size of the second compressed data, and to control the code storing unit to output the combination determined to be output.