| CPC H04N 19/109 (2014.11) [H04N 19/176 (2014.11); H04N 19/186 (2014.11); H04N 19/70 (2014.11)] | 14 Claims |

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1. An image decoding method performed by an image decoding apparatus, the image decoding method comprising:
determining prediction mode characteristic information based on a coding type of a slice including a current block;
determining a prediction mode type of a lower-layer block split from the current block based on the prediction mode characteristic information;
obtaining the lower-layer block by splitting the current block based on the prediction mode type of the lower-layer block; and
decoding the lower-layer block based on the prediction mode type of the lower-layer block,
wherein the prediction mode type of the lower-layer block comprises a first prediction mode type specifying that both an intra prediction mode and an inter prediction mode are available, a second prediction mode type specifying that only the intra prediction mode is available and a third prediction mode type specifying that only the inter prediction mode is available,
wherein, based on a first condition for the current block being satisfied, the prediction mode characteristic information has a first value, and the first condition comprises a case where a color format of the current block is a monochrome format or a 4:4:4 format, and
wherein, based on the first condition for the current block being not satisfied, the prediction mode characteristic information has a second value or a third value based on at least one of the color format, a split mode or a size of the current block.
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