Provided is a video decoding method including: obtaining mode information of a contour for determining at least one segment from a current block; determining whether first coordinates and second coordinates of the contour are derivable from a neighboring block of the current block, based on the mode information of the contour; when the first and second coordinates of the contour are derivable from the neighboring block of the current block, determining the at least one segment from the current block based on the first and second coordinates of the contour derived from the neighboring block of the current block; and performing prediction with respect to the determined at least one segment.