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US 7,248,191 B2Granted
Variable-length coding method, variable-length coding device and imaging system
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsYasuharu Tanaka, Shinji Kitamura, Taichi Nagata
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Abstract
A VLC mode judgment section performs judgment on whether or not a received group (Last, Run, Level) exists in a VLC table and then performs judgment on which one of a first escape mode, a second escape more and a third escape mode is suitable. According to a judgment result of the VLC mode judgment section, an FLC processing section or a coding mode selection section performs variable-length coding using selected one of the received group (Last, Run, Level), a group generated in the first escape mode, and a group generated by the second escape group or fixed-length coding using a third escape mode.
Claims28
A variable-length coding method for generating variable-length coding data from a coefficient series,
- the coefficient series including Run, Level and Last,
- Run indicating the number of zero coefficients before a non-zero coefficient,
- Level indicating a value of a non-zero coefficient,
- Last indicating whether or not the non-zero coefficient is the last coefficient in a DCT coefficient obtained by performing discrete cosine transform to digital data,
- the method comprising:
- a first coefficient series generation step of generating a first coefficient series in which Level is replaced with NewLevel obtained, based on an equation of NewLevel=sign(Level)×(|Level|−LMAX) where sign(Level) is a code of Level and |Level| is an absolute value of Level, using LMAX which is a maximum value of Level corresponding to Last and Run in a given coefficient series in a VLC table showing the correlation between a coefficient series to be variable-length coded and variable-length coding data obtained by variable-length coding the coefficient series,
- a second coefficient series generation step of generating a second coefficient series in which Run in a given coefficient series is replaced with NewRun obtained, based on an equation of NewRun=Run−(RMA+1), using RMAX which is a maximum value of Run corresponding to Last and Level in the given coefficient series in the VLC table;
- a VLC mode judgment step of judging, according to a given coefficient series, which one of a mode for coding the given coefficient series by variable-length coding, a mode for coding the first coefficient series by variable-length coding, a mode for coding the second coefficient series by variable-length coding and a mode for coding the given coefficient series by fixed-length coding should be used;
- a coefficient series output step of outputting, based on a judgment result of the VLC mode judgment step, one of the given coefficient series, the first coefficient series and the second coefficient series;
- a variable-length coding step of generating, based on the VLC table, variable-length coding data from the coefficient series output in the coefficient series outputting step;
- a fixed-length coding step of generating fixed-length coding data obtained by fixed-length coding the coefficient series output in the coefficient series outputting step;
- and
- a coding data outputting step of outputting, based on the judgment result of the VLC judgment step, one of the variable-length coding data and the fixed-length coding data.
10 more elements
A variable-length coding system for generating variable-length coding data from a coefficient series,
- the coefficient series including Run, Level and Last,
- Run indicating the number of zero coefficients before a non-zero coefficient,
- Level indicating a value of a non-zero coefficient,
- Last indicating whether or not the non-zero coefficient is the last coefficient in a DCT coefficient obtained by performing discrete cosine transform to digital data,
- the system comprising:
- a first coefficient series generation section for generating a first coefficient series in which Level is replaced with NewLevel obtained, based on an equation of NewLevel=sign(Level)×(|Level|−LMAX) where sign(Level) is a code of Level and |Level| is an absolute value of Level, using LMAX which is a maximum value of Level corresponding to Last and Run in a given coefficient series in a VLC table showing the correlation between a coefficient series to be variable-length coded and variable-length coding data obtained by variable-length coding the coefficient series;
- a second coefficient series generation section for generating a second coefficient series in which Run in a given coefficient series is replaced with NewRun obtained, based on an equation of NewRun=Run−(RMA+1), using RMAX which is a maximum value of Run corresponding to Last and Level in the given coefficient series in the VLC table;
- a VLC mode judgment section for judging, according to a given coefficient series, which one of a mode for coding the given coefficient series by variable-length coding, a mode for coding the first coefficient series by variable-length coding, a mode for coding the second coefficient series by variable-length coding and a mode for coding a given coefficient series by fixed-length coding should be used;
- a coefficient series output section for outputting, based on a judgment result of the VLC mode judgment section, one of the given coefficient series, the first coefficient series and the second coefficient series;
- a variable-length coding section for generating, based on the VLC table, variable-length length coding data from the coefficient series output in the coefficient series outputting section;
- a fixed-length coding section for generating fixed-length coding data obtained by fixed-length coding the coefficient series output by the coefficient series outputting section;
- and
- a coding data outputting section for outputting, based on the judgment result of the VLC judgment section, one of the variable-length coding data and the fixed-length coding data.
10 more elements
Dependencies are inferred from the claim text.