Method and apparatus for encoding and/or decoding moving pictures

Abstract

A method of encoding moving pictures using a plurality of quantization matrices. The method involves selecting one of the plurality of quantization matrices in consideration of an at least one characteristics of an input image; transforming the input image; and quantizing the transformed input image using the selected quantization matrix.

What is claimed is:  
     
         1 . A method of encoding moving pictures using a plurality of quantization matrices, the method comprising: 
 selecting one of the plurality of quantization matrices in consideration of at least one characteristic of an input image;    transforming the input image; and    quantizing the transformed input image using the selected quantization matrix.    
     
     
         2 . The method of  claim 1 , wherein the at least one characteristic of the input image taken into consideration is a noise information or a spatial characteristic of the input image.  
     
     
         3 . The method of  claim 2 , wherein the noise information is a ratio between a noise variance value and a variance value of the input image.  
     
     
         4 . The method of  claim 2 , wherein the spatial characteristic is a magnitude of an edge included in the input image.  
     
     
         5 . The method of  claim 1 , wherein the transforming comprises selecting and using from among a discrete Fourier transform method, a discrete cosine transform method, and a Hadamard method.  
     
     
         6 . The method of  claim 1 , wherein the plurality of quantization matrices are classified according to the at least one characteristic of the input image.  
     
     
         7 . The method of  claim 1 , wherein the selecting process comprises: 
 selecting one of the plurality of quantization matrices for each of macroblocks of the input image in consideration of the at least one characteristic of the input image and generating an index information for the selected quantization matrix for each of macroblocks; and    outputting the selected quantization matrix for each of macroblocks according to the generated index information.    
     
     
         8 . The method of  claim 7  further comprising: 
 carrying out a variable length decoding on the quantized input image by inserting the index information of the selected quantization matrix into a macroblock header.  
 
     
     
         9 . The method of  claim 8 , wherein the carrying out of the variable length decoding comprises inserting the index information of each of the plurality of quantization matrices into a sequence extension header or a picture extension header.  
     
     
         10 . The method of  claim 7 , wherein the index information is a difference between an index of a quantization matrix corresponding to a macroblock and an index of a quantization matrix corresponding to an adjacent macroblock.  
     
     
         11 . A method of decoding moving pictures using a plurality of quantization matrices, the method comprising: 
 performing a variable length decoding on an encoded image data;    extracting an index information that specifies one of the plurality of quantization matrices, classified according to at least one characteristic of an input image, from the variable-length-decoded image data;    selecting one of the plurality of quantization matrices based on the extracted index information; and    inversely quantizing each of macroblocks of the variable-length-decoded image data using the selected quantization matrix.    
     
     
         12 . The method of  claim 11 , wherein the at least one characteristic of the input image taken into consideration is a noise information or a spatial characteristic of the input image.  
     
     
         13 . The method of  claim 12 , the noise information is a ratio between a noise variance value and a variance value of the input image.  
     
     
         14 . The method of  claim 12 , wherein the spatial characteristic is a magnitude of an edge included in the input image.  
     
     
         15 . The method of  claim 11 , wherein the index information is extracted from a macroblock header.  
     
     
         16 . An apparatus for encoding moving pictures using a plurality of quantization matrices, the apparatus comprising: 
 a quantization matrix determination unit to select one of the plurality of quantization matrices for each of macroblocks in consideration of at least one characteristic of an input image and generates index information indicating the selected quantization matrix for each of macroblocks;    a quantization matrix storage unit to store the plurality of quantization matrices, which are classified according to the characteristics of the input image, and outputs a quantization matrix for each of macroblocks according to the index information generated by the quantization matrix determination unit;    an image transformation unit to transform the input image; and    a quantization unit to quantize the transformed input image using the selected quantization matrix.    
     
     
         17 . The apparatus of  claim 16 , wherein the at least one characteristic of the input image taken into consideration is a noise information or a spatial characteristic of the input image.  
     
     
         18 . The apparatus of  claim 17 , wherein the noise information is a ratio between a noise variance value and a variance value of the input image.  
     
     
         19 . The apparatus of  claim 17 , wherein the spatial characteristic is a magnitude of an edge included in the input image.  
     
     
         20 . The apparatus of  claim 16 , further comprising a variable length encoding unit to perform variable length encoding on the input image quantized by the quantization unit and to insert the index information generated by the quantization matrix determination unit into a macroblock header.  
     
     
         21 . The apparatus of  claim 20 , wherein the variable length encoding unit inserts index information of each of the plurality of quantization matrices into a sequence extension header or a picture extension header.  
     
     
         22 . The apparatus of  claim 16 , wherein the index information is a difference between an index of a quantization matrix corresponding to a macroblock and an index of a quantization matrix corresponding to an adjacent macroblock.  
     
     
         23 . An apparatus for decoding moving pictures using a plurality of quantization matrices, the apparatus comprising: 
 a variable length decoding unit to receive an encoded image stream, to perform variable length decoding on the input image stream, and to extract index information that specifies one of the plurality of quantization matrices, which are classified according to an at least one characteristics of an input image, from each of macroblocks of a variable-length-decoded image stream;    a quantization matrix storage unit to store the plurality of quantization matrices, to select one of the plurality of quantization matrices based on the extracted index information, and to output the selected quantization matrix; and    an inverse quantization unit to inversely quantizes each of macroblocks of the variable-length-decoded image stream using the quantization matrix output from the quantization matrix storage unit.    
     
     
         24 . The apparatus of  claim 23 , wherein at least one characteristic of the input image taken into consideration is a noise information or a spatial characteristic of the input image.  
     
     
         25 . The apparatus of  claim 24 , wherein the noise information is a ratio between a noise variance value and a variance value of the input image.  
     
     
         26 . The apparatus of  claim 24 , wherein the spatial characteristic is a magnitude of an edge included in the input image.  
     
     
         27 . The apparatus of  claim 24 , wherein the index information is included in a macroblock header of the input image stream.