Image quantization parameter encoding method and image quantization parameter decoding method

摘要

An image quantization parameter coding method for encoding a quantization parameter for a video coding process that is based on context-based adaptive binary arithmetic coding, the image quantization parameter coding method comprises: generating a quantization parameter expected from quantization parameter reconstructed in the past; generate a delta of quantization parameter from a quantization parameter and the expected quantization parameter; and encode with binary arithmetic a first bin that indicates whether the quantization parameter delta is significant, other bins, which are later than the first bin, indicate an absolute value of the quantization parameter delta, and a sign bin, which is later to the other bins, it indicates whether the quantization parameter delta is positive or negative, in the case where the quantization parameter delta is significant, where the binary arithmetic coding is performed using context (s) for the first bin and the other bins, and not using context for the sign bin.