Signaling of information indicating transform kernel set in image coding

An encoding apparatus for an image encoding, the encoding apparatus comprising:

• a memory;
• and
• at least one processor connected to the memory, the at least one processor configured to:
• derive residual samples for a current block;
• generate information related to the residual samples for the current block;
• and
• encode image information including the information related to the residual samples to output a bitstream,
• wherein the information related to the residual samples includes information on a multiple transform selection (MTS) index and information on transform coefficients,
• wherein the information on the transform coefficients is generated from the residual samples for the current block using a transform kernel set,
• wherein the MTS index indicates the transform kernel set among transform kernel set candidates,
• wherein at least one bin among bins of a bin string of the MTS index is derived based on a context coding,
• wherein the context coding is performed based on a value of a context index increment for the MTS index,
• wherein the bin string of the MTS index includes up to 4 bins, and a number of context index increment values allocated to a bin which is derived by the context coding among the 4 bins is one,
• wherein a value of the MTS index is represented based on the bin string of the MTS index, and
• wherein the value of the MTS index is represented as one of candidates including 0 to 4.

An apparatus for transmitting data for an image, the apparatus comprising:

• at least one processor configured to obtain a bitstream for the image, wherein the bitstream is generated based on deriving residual samples for a current block, generating information related to the residual samples for the current block, and encoding image information including the information related to the residual samples;
• and
• a transmitter configured to transmit the data comprising the bitstream,
• wherein the information related to the residual samples includes information on a multiple transform selection (MTS) index and information on transform coefficients,
• wherein the information on the transform coefficients is generated from the residual samples for the current block using a transform kernel set,
• wherein the MTS index indicates the transform kernel set among transform kernel set candidates,
• wherein at least one bin among bins of a bin string of the MTS index is derived based on a context coding,
• wherein the context coding is performed based on a value of a context index increment for the MTS index,
• wherein the bin string of the MTS index includes up to 4 bins, and a number of context index increment values allocated to a bin which is derived by the context coding among the 4 bins is one,
• wherein a value of the MTS index is represented based on the bin string of the MTS index, and
• wherein the value of the MTS index is represented as one of candidates including 0 to 4.