Method and apparatus for processing video signal
A method for decoding a video according to the present invention may comprise: decoding information indicating whether illumination compensation is performed for a current block, determining an illumination compensation parameter of the current block when the information indicates that the illumination compensation is performed for the current block, obtaining a prediction block by performing inter prediction for the current block, and performing the illumination compensation on the current block using the illumination compensation parameter.
1. A method of decoding a video, the method comprising:
obtaining a first prediction block of a current block using an L0 reference picture of the current block;
obtaining a second prediction block of the current block using an L1 reference picture of the current block;
obtaining a bi-predicted block of the current block based on a weighted sum operation of the first prediction block and the second prediction block; and
reconstructing the current block based on the bi-predicted block,
wherein if a size of the current block satisfies a pre-defined condition, a first weight applied to the first prediction block and a second weight the second prediction block are determined to be the same,
wherein if the size of the current block does not satisfy the pre-defined condition, the first weight and the second weight are determined based on index information specifying one among a plurality of weight candidates, and
wherein a number of the weight candidates is varied depending on temporal directions of the L0 reference picture and the L1 reference picture.
2. The method of claim 1 , wherein the first weight applied to the first prediction block is derived by subtracting the second weight from a constant value, and
wherein the second weight applied to the second prediction block is determined to be a weight candidate specified by the index information.
3. The method of claim 1 , wherein the number of the weight candidates is different between when both of temporal directions of the L0 reference picture and the L1 reference picture are previous to or subsequent to a current picture, and when temporal directions of the L0 reference picture and the L1 reference picture are different from each other.
4. A method of encoding a video, the method comprising:
obtaining a first prediction block of a current block using an L0 reference picture of the current block;
obtaining a second prediction block of the current block using an L1 reference picture of the current block;
obtaining a bi-predicted block of the current block based on a weighted sum operation of the first prediction block and the second prediction block; and
obtaining a residual block by subtracting the bi-predicted block from an original block of the current block,
wherein if a size of the current block satisfies a pre-defined condition, a first weight applied to the first prediction block and a second weight the second prediction block are determined to be the same,
wherein if the size of the current block does not satisfy the pre-defined condition, the first weight and the second weight are determined based on one among a plurality of weight candidates, index information specifying the one among the plurality of weight candidates being encoded in a bitstream, and
wherein a number of the weight candidates is varied depending on temporal directions of the L0 reference picture and the L1 reference picture.
5. A transmitting apparatus of data for image information, comprising:
at least one processor configured to obtain a bitstream of the image information by performing:
obtaining a first prediction block of a current block using an L0 reference picture of the current block;
obtaining a second prediction block of the current block using an L1 reference picture of the current block;
obtaining a bi-predicted block of the current block based on a weighted sum operation of the first prediction block and the second prediction block; and
obtaining a residual block by subtracting the bi-predicted block from an original block of the current block, and
a transmitter configured to transform the data comprising the bitstream of the image information,
wherein if a size of the current block satisfies a pre-defined condition, a first weight applied to the first prediction block and a second weight the second prediction block are determined to be the same,
wherein if the size of the current block does not satisfy the pre-defined condition, the first weight and the second weight are determined based on one among a plurality of weight candidates, index information specifying the one among the plurality of weight candidates being encoded in a bitstream, and
wherein a number of the weight candidates is varied depending on temporal directions of the L0 reference picture and the L1 reference picture.