Method for encoding/decoding images, and apparatus using same
According to the present invention, an image decoding method for supporting a plurality of layers includes the steps of: receiving and parsing layer-dependent information for reference layers that can be referenced by a current layer in an entire bitstream; when interlayer prediction is used in decoding a current picture in the current layer, receiving and parsing layer information for a reference layer referenced by the current picture among the reference layers; and decoding the current picture on the basis of the layer information.
1. A picture decoding method supporting a plurality of layers, the method comprising:
receiving and parsing layer-dependency information, the layer-dependency information being specified for a pair of a first layer and a second layer and indicating whether or not the first layer is a reference layer of the second layer;
deriving the number of layers that may be referenced in the entire bit stream by the current layer based on the layer-dependency information;
if the number of layers is greater than 0, receiving and parsing flag information indicating whether inter-layer prediction may be used for decoding the current picture in the current layer;
if the flag information is 1 and the number of layers is greater than 1, receiving and parsing inter layer reference picture count information that may specify the number of pictures that may be used for the inter-layer prediction of the current picture;
if the number of layers is not the same as the number of pictures, receiving and parsing layer information specifying a layer of a picture that may be referenced by the current picture among reference layers that are derived based on the layer-dependency information; and
performing the inter-layer prediction based on the layer information,
wherein the layer information is information on an ID of the layer of the picture that may be referenced by the current picture, and the layer information is received, included in a slice header.
2. The picture decoding method of claim 1 , wherein the layer-dependency information is received, included in a video parameter set extension.
3. The picture decoding method of claim 1 , if the flag information is 1, the number of layers is greater than 1, and all of the layers included in the entire bit stream do not use at most one reference layer, the receiving and parsing inter layer reference picture count information is performed.
4. The picture decoding method of claim 3 , wherein the number of pictures is specified as the inter layer reference picture count information plus one.
5. A picture encoding method supporting a plurality of layers, the method comprising:
determining and encoding layer-dependency information on whether or not a layer of two layers is a reference layer of other layer of the two layers in an entire bit stream;
deriving the number of layers that may be referenced in the entire bit stream by the current layer based on the layer-dependency information;
determining and encoding, if the number of layers is greater than 0, flag information indicating whether inter-layer prediction may be used for decoding the current picture in the current layer;
determining and encoding, if the flag information is 1 and the number of layers is greater than 1, inter layer reference picture count information that may specify the number of pictures that may be used for the inter-layer prediction of the current picture; and
determining and encoding, if the number of layers is not the same as the number of pictures, layer information specifying a layer of a picture that may be referenced by the current picture among reference layers that are derived by the layer-dependency information; and
performing inter-layer prediction based on the layer information.
6. A non-transitory computer readable medium storing a bitstream formed by a picture encoding method supporting a plurality of layers, the method comprising:
determining and encoding layer-dependency information on whether or not a layer of two layers is a reference layer of other layer of the two layers in an entire bit stream;
deriving the number of layers that may be referenced in the entire bit stream by the current layer based on the layer-dependency information;
determining and encoding, if the number of layers is greater than 0, flag information indicating whether inter-layer prediction may be used for decoding the current picture in the current layer;
determining and encoding, if the flag information is 1 and the number of layers is greater than 1, inter layer reference picture count information that may specify the number of pictures that may be used for the inter-layer prediction of the current picture; and
determining and encoding, if the number of layers is not the same as the number of pictures, layer information specifying a layer of a picture that may be referenced by the current picture among reference layers that are derived by the layer-dependency information; and
performing inter-layer prediction based on the layer information.