Method and apparatus for image encoding, and method and apparatus for image decoding

An image decoding apparatus, comprising:

• at least one processor configured to:
• obtain one or more luma coding units based on at least one of a split direction and a split type of a luma block;
• decode a luma image based on the obtained one or more luma coding units;
• when an area of a chroma block is smaller than or equal to an area predetermined according to tri split type of the chroma block, determine not to allow splitting of the chroma block according to the tri split type and obtain one or more chroma coding units according to a split type except for the tri split type;
• and
• decode a chroma image based on the obtained one or more chroma coding units according to the split type.

An image encoding method, comprising:

• determining one or more luma coding units based on at least one of a split direction and a split type of a luma block;
• encoding a luma image based on the obtained one or more luma coding units;
• when an area of a chroma block is smaller than or equal to an area predetermined according to tri split type of the chroma block, determining not to allow splitting of the chroma block according to the tri split type and determining one or more chroma coding units according to a split type except for the tri split type;
• and
• encoding a chroma image based on the obtained one or more chroma coding units according to the split type.

A non-transitory computer-readable storage medium storing a bitstream, the bitstream being encoded by an image encoding method comprising:

• determining one or more luma coding units based on at least one of a split direction and a split type of a luma block;
• encoding a luma image based on the obtained one or more luma coding units;
• when an area of a chroma block is smaller than or equal to an area predetermined according to tri split type of the chroma block, determining not to allow splitting of the chroma block according to the tri split type and determining one or more chroma coding units according to a split type except for the tri split type;
• and
• encoding a chroma image based on the obtained one or more chroma coding units according to the split type.