Image encoding and decoding apparatus, and image encoding and decoding method
According to the present invention, an adaptive scheme is applied to an image encoding apparatus that includes an inter-predictor, an intra-predictor, a transformer, a quantizer, an inverse quantizer, and an inverse transformer, wherein input images are classified into two or more different categories, and two or more modules from among the inter-predictor, the intra-predictor, the transformer, the quantizer, and the inverse quantizer are implemented to perform respective operations in different schemes according to the category to which an input image belongs. Thus, the invention has the advantage of efficiently encoding an image without the loss of important information as compared to a conventional image encoding apparatus which adopts a packaged scheme.
1. A video decoding method performed by a video decoding apparatus, the method comprising:
determining whether intra skip coding is applied to a current block;
determining, based on whether the intra skip coding is applied to the current block, whether a contour mode based intra prediction is applicable or not;
obtaining, in case the contour mode based intra prediction is applicable, information specifying whether the contour mode based intra prediction is performed for a current block from a bitstream;
deriving, in case the contour mode based intra prediction is performed for the current block, a first depth value relating to the current block by performing the contour mode based intra prediction for the current block;
deriving, based on the first depth value, a first index value using a first look up table specifying an index value corresponding to a depth value;
deriving a second index value using the first index value and a residual index value, wherein the residual index value specifies a difference between the first index value and the second index value;
obtaining a second depth value relating to the current block based on the second index value and a second look up table specifying a depth value corresponding to an index value;
generating a prediction block for the current block based on the second depth value; and
reconstructing the current block based on the prediction block.
2. The method of claim 1 , wherein the second index value is derived by adding the residual index value to the first index value.
3. A video encoding method performed by a video encoding apparatus, the method comprising:
determining whether intra skip coding is applied to a current block;
determining, based on whether the intra skip coding is applied to the current block, whether a contour mode based intra prediction is applicable or not;
determining, in case the contour mode based intra prediction is applicable, whether the contour mode based intra prediction is performed for a current block or not and information specifying whether the contour mode based intra prediction is performed for a current block being encoded into a bitstream; and
encoding the current block by performing the contour mode based intra prediction for the current block in case the contour mode based intra prediction is performed for the current block,
wherein the contour mode based intra prediction comprises
deriving a first depth value relating to the current block by performing the contour mode based intra prediction for the current block;
deriving, based on the first depth value, a first index value using a first look up table specifying an index value corresponding to a depth value;
deriving a second index value using the first index value and a residual index value, wherein the residual index value specifies a difference between the first index value and the second index value;
obtaining a second depth value relating to the current block based on the second index value and a second look up table specifying a depth value corresponding to an index value; and
generating a prediction block for the current block based on the second depth value.
4. A non-transitory computer-readable recoding-medium storing a bitstream which is generated by a video encoding method, the method comprising:
determining whether intra skip coding is applied to a current block;
determining, based on whether the intra skip coding is applied to the current block, whether a contour mode based intra prediction is applicable or not;
determining, in case the contour mode based intra prediction is applicable, whether the contour mode based intra prediction is performed for a current block or not and information specifying whether the contour mode based intra prediction is performed for a current block being encoded into a bitstream; and
encoding the current block by performing the contour mode based intra prediction for the current block in case the contour mode based intra prediction is performed for the current block,
wherein the contour mode based intra prediction comprises
deriving a first depth value relating to the current block by performing the contour mode based intra prediction for the current block;
deriving, based on the first depth value, a first index value using a first look up table specifying an index value corresponding to a depth value;
deriving a second index value using the first index value and a residual index value, wherein the residual index value specifies a difference between the first index value and the second index value;
obtaining a second depth value relating to the current block based on the second index value and a second look up table specifying a depth value corresponding to an index value; and
generating a prediction block for the current block based on the second depth value.