Image quantization parameter encoding method and image quantization parameter decoding method

An image quantization parameter decoding method for decoding a quantization parameter for a video decoding process that is based on context-based adaptive binary arithmetic coding, the image quantization parameter decoding method comprising:

• binary-arithmetic-decoding a first bin indicating whether or not a delta quantization parameter is significant, other bins, which are subsequent to the first bins indicating an absolute value of the delta quantization parameter, and a sign bin, which is subsequent to the other bins, indicating whether the delta quantization parameter is positive or negative;
• generating a delta quantization parameter by de-binarizing the first bin, the other bins and the sign bin;
• and
• generating a re-constructed quantization parameter by adding a predicted quantization parameter to the delta quantization parameter,
• wherein the binary-arithmetic-decoding is performed using contexts for the first bin and the other bins, and using no context for the sign bin.

An image quantization parameter decoder for decoding a quantization parameter for a video decoding process that is based on context-based adaptive binary arithmetic coding, the image quantization parameter decoder comprising:

• a memory storing instructions;
• and
• a processor configured to execute the instructions to:
• decode by binary-arithmetic-decoding, a first bin indicating whether or not a delta quantization parameter is significant, other bins, which are subsequent to the first bin, indicating an absolute value of the delta quantization parameter, and a sign bin, which is subsequent to the other bins, indicating whether the delta quantization parameter is positive or negative;
• de-binarize the first bin, the other bins and the sign bin to generate a delta quantization parameter;
• and
• add a predicted quantization parameter to the delta quantization parameter to generate a re-constructed quantization parameter,
• wherein the binary-arithmetic-decoding is performed using contexts for the first bin and the other bins, and using no context for the sign bin.