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

Abstract

The invention is directed to a technique capable of improving an coding efficiency by setting a quantization parameter of a peripheral block that is strongly correlated with a quantization parameter of an encoding target block as a prediction value.

What is claimed is: 
     
         1 . An image decoding method comprising:
 acquiring first information of motion compensation which is used for motion compensation processing for a target block which is in a target image and is corresponding to encoded data to be decoded, the first information of motion compensation being based on at least one of images that temporally different from the target image; and   decoding encoded data which is a difference value between a first quantization parameter for the target block and a second quantization parameter for a peripheral block of the target block;   wherein the second quantization parameter is selected based on the acquired first information of motion compensation and a second information of motion compensation used for motion compensation processing of the peripheral block.   
     
     
         2 . The decoding method according to  claim 1 , wherein
 the first information of motion compensation includes information of at least one of a motion vector, a reference image, and a prediction mode for performing motion compensation processing for the target block, and   the second information of motion compensation includes information of at least one of a motion vector, a reference image, and a prediction mode for performing motion compensation processing for the peripheral block.   
     
     
         3 . The decoding method according to  claim 1 , wherein the first information of motion compensation includes a prediction mode used for performing motion compensation processing for the target block, the prediction mode indicating a forward prediction, a backward prediction, or a bidirectional prediction. 
     
     
         4 . The decoding method according to  claim 1 , wherein the first information of motion compensation includes information of a prediction mode which is used for performing motion compensation processing for the target block,
 the second information of motion compensation includes information of a prediction mode which is used for performing motion compensation processing for the peripheral block, and   the second quantization parameter is a quantization parameter of the peripheral block whose prediction mode is the same as the prediction mode of the target block.   
     
     
         5 . The decoding method according to  claim 1 , wherein the first information of motion compensation includes information of a reference image which is used for performing motion compensation processing for the target block,
 the second information of motion compensation includes information of a reference image which is used for performing motion compensation processing for the peripheral block, and   the second quantization parameter is a quantization parameter of the peripheral block whose reference image is same as a reference image of the target block.   
     
     
         6 . The decoding method according to  claim 1 , wherein the first information of motion compensation includes information of a motion vector and a reference image which is used for performing motion compensation processing for the target block,
 the second information of motion compensation includes information of a motion vector and a reference image which is used for performing motion compensation processing for the peripheral block, and   the second quantization parameter is a quantization parameter of the peripheral block of the decoding target block whose motion vector is the similar to a motion vector of the target block and whose reference image coincides with a prediction candidate of reference image of the target block.   
     
     
         7 . The decoding method according to  claim 1 , further comprising
 decoding encoded data relating to motion compensation to generate the first information of motion compensation.   
     
     
         8 . The decoding method according to  claim 1 , further comprising
 obtaining the first information of motion compensation which is used for performing motion compensation processing for the target block.   
     
     
         9 . The decoding method according to  claim 1 , wherein
 the first information of motion compensation includes a prediction mode which is used for performing motion compensation processing for the target block; and   the second quantization parameter is a quantization parameter based on a number of blocks whose prediction mode which is the same as the obtained prediction mode of the target block, the blocks being the peripheral blocks of the target block.   
     
     
         10 . An image decoding apparatus comprising:
 an acquiring unit configured to acquire first information of motion compensation which is used for motion compensation processing for a target block which is in a target image and is corresponding to encoded data to be decoded, the first information of motion compensation being based on at least one of images that temporally different from the target image; and   a decoder configured to decode encoded data which is a difference value between a first quantization parameter for the target block and a second quantization parameter for a peripheral block of the target block;   wherein the second quantization parameter is selected based on the acquired first information of motion compensation and a second information of motion compensation used for motion compensation processing of the peripheral block.   
     
     
         11 . An non-transitory computer readable medium encoded with instructions for an image decoding method comprising:
 instructions for acquiring first information of motion compensation which is used for motion compensation processing for a target block which is in a target image and is corresponding to encoded data to be decoded, the first information of motion compensation being based on at least one of images that temporally different from the target image; and   instructions for decoding encoded data which is a difference value between a first quantization parameter for the target block and a second quantization parameter for a peripheral block of the target block;   wherein the second quantization parameter is selected based on the acquired first information of motion compensation and a second information of motion compensation used for motion compensation processing of the peripheral block.