ENCODING METHOD AND DECODING METHOD

An 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;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, and 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; andencoding 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, 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.