Encoder, decoder, encoding method, and decoding method

An encoding method for encoding image information, the encoding method comprising:

• binarizing a data value indicating the number of non-zero coefficients included in a current basic block which is one of one or more basic blocks in a frequency transform block composed of a plurality of frequency transform coefficients, according to a conversion table in which a plurality of data values and a plurality of binary values are associated with each other, to encode the image information which includes the data value;
• and
• in the binarizing of the data value, selecting the conversion table from a plurality of tables including a first table which includes association with a data value indicating 0 as the number of non-zero coefficients and a second table which does not include association with a data value indicating 0 as the number of non-zero coefficients, and binarizing the data value according to the conversion table selected.

A decoding method for decoding image information, the decoding method comprising:

• inverse binarizing a binary value which has been obtained by binarizing a data value according to a conversion table in which a plurality of data values and a plurality of binary values are associated with each other, to decode the image information which includes the data value, the data value indicating the number of non-zero coefficients included in a current basic block which is one of one or more basic blocks in a frequency transform block composed of a plurality of frequency transform coefficients;
• and
• in the inverse binarizing of the data value, selecting the conversion table from a plurality of tables including a first table which includes association with a data value indicating 0 as the number of non-zero coefficients and a second table which does not include association with a data value indicating 0 as the number of non-zero coefficients, and inverse binarizing the binary value according to the conversion table selected.