MOTION IMAGE ENCODING METHOD AND MOTION IMAGE DECODING METHOD

摘要

A motion image encoding method and a motion image decoding method for improving the encoding efficiency and the quality of motion images. A motion image encoding apparatus (100) comprising a mode deciding part (111) for deciding one of implicit and explicit methods as a method of notifying a transformed block size by which to perform an orthogonal transformation of a target block and then outputting an ABT mode indicative of the decided notifying method; an orthogonal transformation part (104) for transforming, to a frequency coefficient, a difference value between an input image and an expected image by the transformed block size decided inaccordance with the decided notifying method; a quantizing part (105) for quantizing the frequency coefficient to output a quantized value; and a variable-length encoding part (110) for variable-length encoding the quantized value, the ABT mode and so on to output an encoded stream.