Image coding method for coding information indicating coding scheme

An image coding and decoding method for coding an image on a block-by-block basis and for decoding a bitstream obtained through the coding of the image on the block-by-block basis, the image coding and decoding method comprising:

• coding a first flag that indicates whether a predetermined extension standard of a predetermined image coding standard is used;
• coding, when the first flag indicates that the extension standard is used, a second flag that indicates whether a first scheme is used for coding a current block to be coded included in the image, the first scheme being included in the extension standard;
• coding, when the first flag indicates that the extension standard is used, a third flag that indicates whether a third scheme is used for coding the image, the third scheme being included in the extension standard;
• performing prediction on the current block to generate a residual signal, the residual signal indicating a difference between the current block and the predicted current block;
• and
• coding, when the second flag indicates that the first scheme is used, the current block by coding a difference between adjacent-to-each-other samples of the current block using the first scheme, the samples being obtained from the residual signal;
• coding, when the third flag indicates that the third scheme is used, the image using the third scheme;
• decoding, from the bitstream, the first flag that indicates whether the predetermined extension standard of the image coding standard is used;
• decoding, from the bitstream, when the first flag indicates that the extension standard is used, the second flag that indicates whether the first scheme is used;
• decoding, from the bitstream, when the first flag indicates that the extension standard is used, the third flag that indicates whether the third scheme is used;
• decoding the residual signal of the current block that indicates the difference between the current block and the predicted current block;
• decoding, from the bitstream, when the second flag indicates that the first scheme is used, the current block by decoding, from the bitstream, the difference between the adjacent-to-each-other samples of the current block using the first scheme;
• and
• decoding, from the bitstream, when the third flag indicates that the third scheme is used, the image using the third scheme,
• wherein the second flag and the third flag are included in headers of different layers, with the first flag corresponding to each of the second flag and the third flag being included in each of the headers.