IMAGE CODING METHOD, IMAGE DECODING METHOD, IMAGE CODING DEVICE, IMAGE DECODING DEVICE, AND IMAGE CODING/DECODING DEVICE

摘要

Provided is an image coding method whereby a transformation is carried out on a color difference component and a brightness component of an input image and the input image coded. The input image includes one or a plurality of coding blocks. Each coding block includes one or a plurality of transform blocks. The brightness component block size in the transform block to be processed is the same as the size of the transform block to be processed. The color difference component block size in the transform block to be processed is smaller than the brightness component block size. The image coding method comprises: a step of, if the size of the transform block to be processed is a predetermined first smallest size, executing a transform on the color difference component with a block of the same size as the brightness component by coupling a plurality of color difference component blocks; and a step of, if the size of the transform block to be processed is the first smallest size, not coding a CBF flag which denotes whether a nonzero coefficient is included in a color difference component coefficient, and, if the size of the transform block to be processed is of another size, coding the CBF flag.