Method and device for signaling information on chroma format

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:
• generate chroma format indicator information representing a chroma format;
• derive a chroma array type based on the chroma format indicator information;
• derive prediction samples for a current block based on the chroma format indicator information;
• derive residual samples for the current block based on the prediction samples;
• and
• encode image information including residual information including information related to the residual samples,
• wherein based on a value of the chroma format indicator information being not equal to 0 and a tree type for the current block being a single tree or a dual tree chroma, intra chroma prediction mode information for the current block is further encoded,
• wherein the intra chroma prediction mode information represents an intra chroma prediction mode used for deriving the prediction samples for the current block, and
• wherein based on the value of the chroma format indicator information being not equal to 0, a dual tree intra flag related to whether each coding tree unit (CTU) is split into coding units (CUs) of a predefined area using implicit quadtree split is further encoded.

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

• at least one processor configured to obtain encoded information for the image, wherein the encoded information includes encoded residual information, wherein the encoded residual information is generated by performing steps of generating chroma format indicator information representing a chroma format, deriving a chroma array type based on the chroma format indicator information, deriving prediction samples for a current block based on the chroma format indicator information, deriving residual samples for the current block based on the prediction samples, and encoding image information including residual information including information related to the residual samples;
• and
• a transmitter configured to transmit the data comprising the bitstream,
• wherein based on a value of the chroma format indicator information being not equal to 0 and a tree type for the current block being a single tree or a dual tree chroma, intra chroma prediction mode information for the current block is further encoded,
• wherein the intra chroma prediction mode information represents an intra chroma prediction mode used for deriving the prediction samples for the current block, and
• wherein based on the value of the chroma format indicator information being not equal to 0, a dual tree intra flag related to whether each coding tree unit (CTU) is split into coding units (CUs) of a predefined area using implicit quadtree split is further encoded.