IMAGE ENCODING APPARATUS, IMAGE DECODING APPARATUS, IMAGE ENCODING METHOD AND IMAGE DECODING METHOD

摘要

PROBLEM TO BE SOLVED: To provide an image encoding apparatus and method and image decoding apparatus and method in which optimality is improved for encoding ultra high definition video signals.SOLUTION: An image encoding apparatus comprises a prediction section 4 and a variable length encoding section 8. The prediction section 4 adaptively determines the size of a motion prediction unit block in accordance with a color component signal, divides the motion prediction unit blocks into motion vector allocation regions and searches a motion vector. When allocating a motion vector to the overall motion prediction unit block, in the case where the motion vector is equal to a prediction vector and a prediction error signal 5 is not present, the variable length encoding section 8 performs encoding in a mc_skip mode. When the motion vector allocation region is equal to or larger than a predetermined size and the motion vector is to be allocated to the overall motion vector allocation region, in the case where the motion vector is equal to the prediction vector and the prediction error signal 5 is not present, the variable length encoding section 8 performs encoding in a sub_mc_skip mode.