Image encoder and image decoder

Abstract

A division mode adapted to the characteristic of an image is enabled to be selected from among a plurality of the division modes while suppressing an increase in side information. An image encoder (1) divides an input image into a plurality of macro blocks and performs encoding processing in units of macro blocks. The image encoder (1) is provided with a prediction mode assessment portion (148) for assessing a prediction mode indicating a method of generating a prediction image for each of the macro-blocks, a division mode determination portion (149) for determining a division mode indicating a method of division into sub-macro blocks for each of the macro blocks according to the prediction modes assessed by the prediction mode assessment portion (148), an SMB division portion (140) for dividing the macro blocks into the sub-macro blocks on the basis of the division modes determined by the division mode determination portion (149), and a prediction portion (141) for generating the prediction images of the macro blocks on the basis of the prediction modes assessed by the prediction mode assessment portion (148), and frequency-converts the difference between the input image and the prediction images in units of sub-macro blocks.

Dependencies are inferred from the claim text.