Image encoding and decoding apparatus, and image encoding and decoding method

Abstract

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.

What is claimed is: 
     
         1 . A video encoding apparatus comprising:
 an image analyzer configured to analyze image characteristics for an input image in units of coding blocks and classify the coding blocks into two or more categories based on the image characteristics; and   a transformer configured to perform a transform by referring to the categories of the coding blocks.   
     
     
         2 . The video encoding apparatus of  claim 1 , wherein the image characteristics include information about at least one of directivity, an edge component distribution, and a color format of the image. 
     
     
         3 . The video encoding apparatus of  claim 1 , wherein the two or more categories are classified to include at least one of screen content including text or graphics, a natural image, and a depth map. 
     
     
         4 . The video encoding apparatus of  claim 1 , further comprising:
 a color format converter configured to convert color formats of the coding blocks by referring to the categories of the coding blocks.   
     
     
         5 . The video encoding apparatus of  claim 1 , wherein the transformer skips the transform by referring to the categories of the coding blocks. 
     
     
         6 . The video encoding apparatus of  claim 1 , further comprising:
 a quantizer configured to perform quantization by referring to the categories of the coding blocks.   
     
     
         7 . The video encoding apparatus of  claim 6 , wherein the quantizer skips the quantization by referring to the categories of the coding blocks. 
     
     
         8 . The video encoding apparatus of  claim 1 , further comprising:
 an intra-predictor configured to perform intra-prediction by referring to the categories of the coding blocks;   an inter-predictor configured to perform inter-prediction by referring to the categories of the coding blocks; and   a filter configured to perform filtering by referring to the categories of the coding blocks.   
     
     
         9 . The video encoding apparatus of  claim 8 ,
 wherein the intra-predictor skips the intra-prediction by referring to the categories of the coding blocks, and   wherein the filter changes resolution by referring to the categories of the coding blocks.   
     
     
         10 . The video encoding apparatus of  claim 8 , wherein the intra-predictor performs the intra-prediction by representing a pixel of the image by an index of a preset lookup table (LUT) when the category of the coding block is a depth map. 
     
     
         11 . A video decoding apparatus comprising:
 a decoder configured to calculate categories of coding blocks classified into two or more categories based on image characteristics for an input image analyzed in units of coding blocks by decoding a bitstream;   an inverse quantizer configured to perform inverse quantization by referring to the categories of the coding blocks; and   an inverse transformer configured to perform an inverse transform by referring to the categories of the coding blocks.   
     
     
         12 . The video decoding apparatus of  claim 11 , wherein the image characteristics include information about at least one of directivity, an edge component distribution, and a color format of the image. 
     
     
         13 . The video decoding apparatus of  claim 11 , wherein the two or more categories are classified to include at least one of screen content including text or graphics, a natural image, and a depth map. 
     
     
         14 . The video decoding apparatus of  claim 11 , wherein the decoder calculates color formats of the coding blocks based on the categories of the coding blocks. 
     
     
         15 . The video decoding apparatus of  claim 11 , wherein the inverse quantizer skips the inverse quantization by referring to the categories of the coding blocks 
     
     
         16 . The video decoding apparatus of  claim 11 , wherein the inverse transformer skips the inverse transform by referring to the categories of the coding blocks. 
     
     
         17 . The video decoding apparatus of  claim 11 , further comprising:
 an intra-predictor configured to perform intra-prediction by referring to the categories of the coding blocks;   an inter-predictor configured to perform inter-prediction by referring to the categories of the coding blocks; and   a filter configured to perform filtering by referring to the categories of the coding blocks.   
     
     
         18 . The video decoding apparatus of  claim 17 ,
 wherein the intra-predictor skips the intra-prediction by referring to the categories of the coding blocks, and   wherein the filter changes resolution by referring to the categories of the coding blocks.   
     
     
         19 . The video decoding apparatus of  claim 17 , wherein the intra-predictor performs the intra-prediction by representing a pixel of the image by an index of an LUT when the category of the coding block is a depth map. 
     
     
         20 . A video decoding method comprising:
 calculating categories of coding blocks classified into two or more categories based on image characteristics for an input image analyzed in units of coding blocks by decoding a bitstream;   performing inverse quantization by referring to the categories of the coding blocks; and   performing an inverse transform by referring to the categories of the coding blocks.   
     
     
         21 . The video decoding method of  claim 20 , wherein the calculating includes:
 calculating color formats of the coding blocks based on the categories of the coding blocks.   
     
     
         22 . The video decoding method of  claim 20 , further comprising:
 performing intra-prediction by referring to the categories of the coding blocks;   performing inter-prediction by referring to the categories of the coding blocks; and   performing filtering by referring to the categories of the coding blocks.