Picture coding method and picture decoding method
View Patent ↗The method includes the following units: a coefficient number detecting unit ( 109 ) for detecting the number of coefficients which has a value other than 0 for each block according to the generated coefficient, a coefficient number storing unit ( 110 ) for storing the number of coefficients detected, a coefficient number coding unit ( 111 ) for selecting a table for variable length coding based on the numbers of coefficients in the coded blocks located on the periphery of a current block to be coded with reference to the selected table for variable length coding so as to perform variable length coding for the number of coefficients.
1. A decoding method for decoding coded data on a block basis, the method comprising:
determining whether a first decoded block located above a target block and a second decoded block located to the left of the target block are located inside or outside of a slice that includes the target block;
predicting a predictive value for a total number of non-zero coefficients included in the target block to be decoded based on a mean value of a total number of non-zero coefficients included in the first decoded block and a total number of non-zero coefficients included in the second decoded block when the first decoded block and the second decoded block are inside the slice including the target block, and predicting a predictive value for a total number of non-zero coefficients included in the target block to be decoded to be a value of “0” when the first decoded block and the second decoded block are outside the slice including the target block, wherein each non-zero coefficient is a transform coefficient having a level value other than “0”;
selecting a variable length code table based on the predictive value; and
decoding the coded data by using the selected variable length code table to obtain an actual value of a total number of non-zero coefficients included in the target block.
2. A picture reconstructing method for reconstructing a picture from coded data obtained by coding a picture on a block basis, the method comprising:
decoding the coded data to obtain a total number of non-zero coefficients included in a first block located above a target block and a total number of non-zero coefficients included in a second block located to the left of the target block, each non-zero coefficient being a transform coefficient having a level value other than “0”;
determining whether the first block and the second block are located inside or outside of a slice that includes the target block;
predicting, according to said determining, a predictive value for a total number of non-zero coefficients included in the target block to be decoded based on a mean value of the total number of non-zero coefficients included in the first block and the total number of non-zero coefficients included in the second block;
selecting a variable length code table based on the predictive value;
decoding the coded data to obtain an actual value of a total number of non-zero coefficients included in the target block;
decoding the coded data by using the obtained actual value to obtain a decoded target block; and
reconstructing a reconstructed picture by using the decoded target block.
3. A non-transitory computer-readable medium having stored thereon a program for decoding coded data on a block basis, the program causing a computer to execute a method comprising:
determining whether a first decoded block located above a target block and a second decoded block located to the left of the target block are located inside or outside of a slice that includes the target block;
predicting a predictive value for a total number of non-zero coefficients included in the target block to be decoded based on a mean value of a total number of non-zero coefficients included in the first decoded block and a total number of non-zero coefficients included in the second decoded block, when the first decoded block and the second decoded block are inside the slice including the target block, and predicting a predictive value for a total number of non-zero coefficients included in the target block to be decoded to be a value of “0” when the first decoded block and the second decoded block are outside the slice including the target block, wherein each non-zero coefficient is a transform coefficient having a level value other than “0”;
selecting a variable length code table based on the predictive value; and
decoding the coded data by using the selected variable length code table to obtain an actual value of a total number of non-zero coefficients included in the target block.