In an image encoding apparatus, pattern image cut-out means cuts out partial regions of an image of image data and generates pattern images. At the same time, the pattern image cut-out means outputs position information that is representative of positions on the image data, from which the pattern images are cut out. Rearrangement means receives the generated pattern images, rearranges the pattern images, and outputs the rearranged pattern images. Dictionary generating means generates list information in which the rearranged pattern images are put together in the form of, e.g. a list. Pattern image synthesis means generates a single image ("pattern image synthesis image") in which the pattern images are combined in order. Encoded data generating means generates and outputs final encoded data, on the basis of the generated pattern image synthesis image and the generated pattern image position information.