Apparatus and method for inverse quantization

A method for quantization of a picture block, the method comprising:

• performing quantization on a chrominance component of the picture block using a determined quantization parameter (QP) value;
• obtaining one or more existing QP values and including the one or more existing QP values into a bitstream, wherein the one or more existing QP values are associated with the chrominance component of the picture block;
• determining a QP parameter for the chrominance component of the picture block based on the one or more existing QP values and the determined QP value;
• and
• including the QP parameter into the bitstream;
• wherein
• the one or more existing QP values comprises a QP value of a collocated block in the luminance component, wherein the QP value for the luminance component is not a delta QP value;
• and
• determining the QP parameter for the chrominance component of the picture block based on the one or more existing QP values and the determined QP value comprises:
• determining the QP parameter for the chrominance component of the picture block based on the QP value of the collocated block in the luminance component and the determined QP value.

A decoding apparatus for boundary partition of a picture block, the decoding apparatus comprising:

• one or more processors;
• and
• a non-transitory computer-readable storage medium coupled to the processors and storing programming instructions, which when executed by the processors, cause the decoding apparatus to:
• obtain one or more existing quantization parameter (QP) values from a bitstream, wherein the one or more existing QP values are associated with a chrominance component of the picture block;
• determine a QP value for the chrominance component of the picture block based on the one or more existing QP values;
• and
• perform inverse quantization on the chrominance component of the picture block using the determined QP value;
• wherein the one or more existing QP values comprises a QP value for a luminance component of the picture block collocated with the chrominance component of the picture block, wherein the QP value for the luminance component is not a delta QP value;
• wherein to determine the QP value for the chrominance component of the picture block based on the one or more existing QP values, the programming instructions, which when executed by the processors, cause the decoding apparatus to:
• determine the QP value for the chrominance component of the picture block based on the QP value for the luminance component of the picture block collocated with the chrominance component of the picture block.