Video decoding method, video decoder, video encoding method and video encoder

Abstract

A video decoding method includes: receiving a coding value; and performing the following steps according to an index value of the coding value: collecting a plurality of reference samples, grouping the plurality of reference samples to generate at least one group, establishing a model of the at least one group, obtaining a target pixel from a target block, selecting a target group from the at least one group, and introducing a luminance value of the target pixel into a model of the target group to predict a chromaticity value of the target pixel.

What is claimed is: 
     
         1 . A video decoding method, comprising:
 receiving a coding value, and performing steps below according to an index value of the coding value:
 collecting a plurality of reference samples; 
 grouping the reference samples to generate at least one group; 
 establishing a model of the at least one group; 
 obtaining a target pixel from a target block; 
 selecting a target group from the at least one group according to the target pixel; and 
 introducing a luminance value of the target pixel into a model of the target group to predict a chromaticity value of the target pixel. 
   
     
     
         2 . The video decoding method according to  claim 1 , wherein a quantity of the groups generated is one. 
     
     
         3 . The video decoding method according to  claim 1 , wherein a quantity of the groups generated is any number more than two. 
     
     
         4 . The video decoding method according to  claim 1 , wherein the step of grouping the reference samples comprises:
 calculating an average luminance value of the reference samples; and   assigning, according to whether respective luminance values of the reference samples are greater than or smaller than the average luminance value, the reference samples into the at least one generated group.   
     
     
         5 . The video decoding method according to  claim 1 , wherein the step of grouping the reference samples comprises:
 establishing a first group according to a first reference sample of the reference samples, and assigning the first reference sample into the first group;   determining, according to a sample characteristic value of a second reference sample of the reference samples, whether to add the second reference sample into the first group;   if it is determined to add the second reference sample into the first group, updating a group characteristic value of the first group; and   if it is determined not to add the second reference sample into the first group, establishing a second group and calculating a group characteristic value of the second group.   
     
     
         6 . The video decoding method according to  claim 5 , wherein the group characteristic value comprises any combination of: a position, a representative luminance value, a representative chromaticity component value, a maximum luminance, a minimum luminance, a maximum chromaticity, a minimum chromaticity and a reference sample quantity; and the sample characteristic value comprises any combination of: a luminance, at least one chromaticity component and a position. 
     
     
         7 . The video decoding method according to  claim 1 , wherein the step of grouping the reference samples comprises:
 defining a quantity of the at least one group;   establishing the at least one group of a fixed quantity, and calculating individual group characteristic values of the at least one group according to individual sample characteristic values of a plurality of reference samples of the at least one group; and   assigning the reference samples into the at least one group according to the individual sample characteristic values.   
     
     
         8 . The video decoding method according to  claim 7 , wherein the group characteristic value comprises any combination of: a position, a representative luminance value, a representative chromaticity component value, a maximum luminance, a minimum luminance, a maximum chromaticity, a minimum chromaticity and a reference sample quantity; and the sample characteristic value comprises any combination of: a luminance, at least one chromaticity component and a position. 
     
     
         9 . The video decoding method according to  claim 1 , wherein the step of establishing the model of the at least one group comprises:
 establishing the model by applying a linear regression algorithm.   
     
     
         10 . The video decoding method according to  claim 1 , wherein the step of establishing the model of the at least one group comprises:
 establishing the model by applying a straight line equation.   
     
     
         11 . The video decoding method according to  claim 1 , wherein the step of establishing the model of the at least one group comprises:
 establishing the model by applying an averaging algorithm.   
     
     
         12 . The video decoding method according to  claim 1 , wherein the step of selecting the target group from the at least one group comprises:
 identifying from the at least one group the target group nearest to the target pixel according to the luminance value of the target pixel.   
     
     
         13 . The video decoding method according to  claim 1 , wherein, if a luminance value of a previously processed target pixel is near the luminance value of the target pixel, the chromaticity value of the target pixel is predicted by using a predicted chromaticity value of the previously processed target pixel. 
     
     
         14 . The video decoding method according to  claim 1 , wherein:
 a spatial position of a characteristic value discontinuity is identified to segment a reference block and the target block, wherein the reference block is segmented into at least one reference sub-block, and a group is established for the at least one reference sub-block; and   at least one model is established by using the at least one reference sub-block.   
     
     
         15 . The video decoding method according to  claim 1 , wherein the step of predicting the chromaticity value of the target pixel comprises:
 segmenting the target block into at least one target sub-block according to a spatial position of a characteristic value discontinuity;   selecting the target group according to the target sub-block to which the target pixel belongs; and   predicting the chromaticity value of the target pixel by using the model of the target group.   
     
     
         16 . The video decoding method according to  claim 1 , wherein the reference sample is collected from a left adjacent block and an upper adjacent block of the target block. 
     
     
         17 . A video encoding method, comprising:
 collecting a plurality of reference samples;   grouping the reference samples to generate at least one group;   establishing a model of the at least one group;   obtaining a target pixel from a target block;   selecting a target group from the at least one group according to the target pixel;   introducing a luminance value of the target pixel into a model of the target group to predict a chromaticity value of the target pixel; and   generating a coding value, the coding value having an index value.   
     
     
         18 . The video encoding method according to  claim 17 , wherein a quantity of the groups generated is one. 
     
     
         19 . The video encoding method according to  claim 17 , wherein a quantity of the groups generated is any number more than two. 
     
     
         20 . The video encoding method according to  claim 17 , wherein the step of grouping the reference samples comprises:
 calculating an average luminance value of the reference samples; and   assigning, according to whether respective luminance values of the reference samples are greater than or smaller than the average luminance value, the reference samples into the at least one generated group.   
     
     
         21 . The video encoding method according to  claim 17 , wherein the step of grouping the reference samples comprises:
 establishing a first group according to a first reference sample of the reference samples, and assigning the first reference sample into the first group;   determining, according to a sample characteristic value of a second reference sample of the reference samples, whether to add the second reference sample into the first group;   if it is determined to add the second reference sample into the first group, updating a group characteristic value of the first group; and   if it is determined not to add the second reference sample into the first group, establishing a second group and calculating a group characteristic value of the second group.   
     
     
         22 . The video encoding method according to  claim 21 , wherein the group characteristic value comprises any combination of: a position, a representative luminance value, a representative chromaticity component value, a maximum luminance, a minimum luminance, a maximum chromaticity, a minimum chromaticity and a reference sample quantity; and the sample characteristic value comprises any combination of: a luminance, at least one chromaticity component and a position. 
     
     
         23 . The video encoding method according to  claim 17 , wherein the step of grouping the reference samples comprises:
 defining a quantity of the at least one group;   establishing the at least one group of a fixed quantity, and calculating individual group characteristic values of the at least one group according to individual sample characteristic values of a plurality of reference samples of the at least one group; and   assigning the reference samples into the at least one group according to the individual sample characteristic values.   
     
     
         24 . The video encoding method according to  claim 23 , wherein the group characteristic value comprises any combination of: a position, a representative luminance value, a representative chromaticity component value, a maximum luminance, a minimum luminance, a maximum chromaticity, a minimum chromaticity and a reference sample quantity; and the sample characteristic value comprises any combination of: a luminance, at least one chromaticity component and a position. 
     
     
         25 . The video encoding method according to  claim 17 , wherein the step of establishing the model of the at least one group comprises:
 establishing the model by applying a linear regression algorithm.   
     
     
         26 . The video encoding method according to  claim 17 , wherein the step of establishing the model of the at least one group comprises:
 establishing the model by applying a straight line equation.   
     
     
         27 . The video encoding method according to  claim 17 , wherein the step of establishing the model of the at least one group comprises:
 establishing the model by applying an averaging algorithm.   
     
     
         28 . The video encoding method according to  claim 17 , wherein the step of selecting the target group from the at least one group comprises:
 identifying from the at least one group the target group nearest to the target pixel according to the luminance value of the target pixel.   
     
     
         29 . The video encoding method according to  claim 17 , wherein, if a luminance value of a previously processed target pixel is near the luminance value of the target pixel, the chromaticity value of the target pixel is predicted by using a predicted chromaticity value of the previously processed target pixel. 
     
     
         30 . The video encoding method according to  claim 17 , wherein:
 a spatial position of a characteristic value discontinuity is identified to segment a reference block and the target block, wherein the reference block is segmented into at least one reference sub-block, and a group is established for the at least one reference sub-block; and   at least one model is established by using the at least one reference sub-block.   
     
     
         31 . The video encoding method according to  claim 17 , wherein the step of predicting the chromaticity value of the target pixel comprises:
 segmenting the target block into at least one target sub-block according to a spatial position of a characteristic value discontinuity;   selecting the target group according to the target sub-block to which the target pixel belongs; and   predicting the chromaticity value of the target pixel by using the model of the target group.   
     
     
         32 . The video encoding method according to  claim 17 , wherein the reference sample is collected from a left adjacent block and an upper adjacent block of the target block. 
     
     
         33 . A video decoder, comprising:
 a processor, for controlling the video decoder;   a memory, for storing a plurality of reference samples and a target block;   a decoding module; and   an index receiving module, receiving a coding value;   wherein, the processor, the memory, the decoding module and the index receiving module are coupled to one another; and the decoding module performs operations below according to an index value of the coding value:
 collecting a plurality of reference samples; 
 grouping the reference samples to generate at least one group; 
 establishing a model of the at least one group; 
 obtaining a target pixel from a target block; 
 selecting a target group from the at least one group according to the target pixel; and 
 introducing a luminance value of the target pixel into a model of the target group to predict a chromaticity value of the target pixel. 
   
     
     
         34 . A video encoder, comprising:
 a processor, for controlling the video encoder;   a memory, for storing a plurality of reference samples and a target block;   an encoding module; and   an index selecting module;   wherein, the processor, the memory, the encoding module and the index selecting module are coupled to one another; and the encoding module performs operations below:
 collecting a plurality of reference samples; 
 grouping the reference samples to generate at least one group; 
 establishing a model of the at least one group; 
 obtaining a target pixel from a target block; 
 selecting a target group from the at least one group according to the target pixel; 
 introducing a luminance value of the target pixel into a model of the target group to predict a chromaticity value of the target pixel; and 
 generating a coding value; and 
   the index selecting module generates an index value from the coding value generated by the encoding module.