Image processing method and image processing apparatus for images decodable at multiple resolutions

An image processing method to control an image processing device. Encoded data of tiles of acquired image data is encoded to be decodable at multiple resolutions. The method determines whether encoded data of each tile consists of data of at least three tile-parts, each being at a resolution level. Decoding the data of some tile-parts results in an image resolution that is different from that obtained by decoding other tile-parts data. Tile-parts are designated to be decoded to obtain a designated resolution image. If it is determined that an acquired tile encoded data consists of the data of the at least three tile-parts, data of designated tile-parts is decoded. An image obtained by the decoding is resized and output. Depending on whether encoded data of each acquired tile in the encoded image data consists of the data of the at least three tile-parts, the acquired encoded image data is reconstructed.