Image decoding method, image coding method, image decoding apparatus, image coding apparatus, program, and integrated circuit

摘要

An image decoding method comprises: a matrix acquisition step for acquiring a past quantization scaling matrix that is an already decoded quantization scaling matrix and used for decoding a new quantization scaling matrix; an update parameter acquisition step for acquiring, from an encoded stream, an update parameter indicating the amount of change of the new quantization scaling matrix with respect to the past quantization scaling matrix; a matrix decoding step for decoding the new quantization scaling matrix using the past quantization scaling matrix acquired in the matrix acquisition step and the update parameter acquired in the update parameter acquisition step; and an image decoding step for decoding an encoded image using the new quantization scaling matrix decoded in the matrix decoding step.