Encoding device, decoding device, encoding method, and decoding method for coding efficiency

An electronic apparatus, comprising:

• encoder circuitry configured to:
• encode a first denominator for a luma weighting factor;
• encode a first difference value that is equal to a value of a difference between the first denominator and a second denominator for a chroma weighting factor;
• encode a second difference value of the luma weighting factor, wherein the second difference value is equal to a value of a difference between the luma weighting factor and a first reference value, and the first reference value is equal to a value obtained by left shift of “1” by at least one binary digit specified by the first denominator, and the second difference value is in a fixed range of −128 to +127 regardless of the first denominator;
• encode a third difference value of the chroma weighting factor, wherein the third difference value is equal to a value of a difference between the chroma weighting factor and a second reference value, the second reference value is equal to a value obtained by left shift of “1” by at least one binary digit specified by the second denominator, and the third difference value is in a fixed range of −128 to +127 regardless of the second denominator;
• and
• encode a fourth difference value of a chroma offset, wherein the fourth difference value is equal to a value of a difference between the chroma offset and a third reference value, the fourth difference value is in a fixed range of −2n to +2n−1, and the third reference value is equal to a value obtained by subtracting a value obtained by both multiplying a median value of a maximum pixel value by the chroma weighting factor and shifting to right for the at least one binary digit specified by the second denominator, from the median value.

A encoding method, comprising:

• encoding a first denominator for a luma weighting factor;
• encoding a first difference value that is equal to a value of a difference between the first denominator and a second denominator for a chroma weighting factor;
• encoding a second difference value of the luma weighting factor, wherein the second difference value is equal to a value of a difference between the luma weighting factor and a first reference value, and the first reference value is equal to a value obtained by left shift of “1” by at least one binary digit specified by the first denominator, and the second difference value is in a fixed range of −128 to +127 regardless of the first denominator;
• encoding a third difference value of the chroma weighting factor, wherein the third difference value is equal to a value of a difference between the chroma weighting factor and a second reference value, the second reference value is equal to a value obtained by left shift of “1” by at least one binary digit specified by the second denominator, and the third difference value is in a fixed range of −128 to +127 regardless of the second denominator;
• and
• encoding a fourth difference value of a chroma offset, wherein the fourth difference value is equal to a value of a difference between the chroma offset and a third reference value, the fourth difference value is in a fixed range of −2n to +2n−1, and the third reference value is equal to a value obtained by subtracting a value obtained by both multiplying a median value of a maximum pixel value by the chroma weighting factor and shifting to right for the at least one binary digit specified by the second denominator, from the median value.

A non-transitory computer readable medium storing computer executable instructions that, when executed by encoder circuitry, cause the encoder circuitry to:

• encode a first denominator for a luma weighting factor;
• encode a first difference value that is equal to a value of a difference between the first denominator and a second denominator for a chroma weighting factor;
• encode a second difference value of the luma weighting factor, wherein the second difference value is equal to a value of a difference between the luma weighting factor and a first reference value, and the first reference value is equal to a value obtained by left shift of “1” by at least one binary digit specified by the first denominator, and the second difference value is in a fixed range of −128 to +127 regardless of the first denominator;
• encode a third difference value of the chroma weighting factor, wherein the third difference value is equal to a value of a difference between the chroma weighting factor and a second reference value, the second reference value is equal to a value obtained by left shift of “1” by at least one binary digit specified by the second denominator, and the third difference value is in a fixed range of −128 to +127 regardless of the second denominator;
• and
• encode a fourth difference value of a chroma offset, wherein the fourth difference value is equal to a value of a difference between the chroma offset and a third reference value, the fourth difference value is in a fixed range of −2n to +2n−1, and the third reference value is equal to a value obtained by subtracting a value obtained by both multiplying a median value of a maximum pixel value by the chroma weighting factor and shifting to right for the at least one binary digit specified by the second denominator, from the median value.