IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
US-0069622
(2005-02-28)
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등록번호 |
US-7499596
(2009-03-03)
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발명자
/ 주소 |
- Chen,Wen hsiung
- Wu,Fang
- Pelton,Gregory D.
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출원인 / 주소 |
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
6 인용 특허 :
93 |
초록
▼
A method, apparatus, and a computer readable hardware storage medium with instructions to encode a series of quantized transform coefficients. The method includes identifying runs of one or more non-zero coefficients, and for each such run, identifying events of consecutive amplitude-1 coefficients
A method, apparatus, and a computer readable hardware storage medium with instructions to encode a series of quantized transform coefficients. The method includes identifying runs of one or more non-zero coefficients, and for each such run, identifying events of consecutive amplitude-1 coefficients followed by a single amplitude>1 coefficient. The method further includes encoding the identified event with a codeword, each event identified according to the length of the consecutive amplitude-1 coefficients and the amplitude of the ending coefficient. The method is such that relatively short codewords are formed to represent values or sequences of values that are relatively more likely-to-occur, and relatively long codewords are formed to represent values or sequences of values that are relatively less likely-to-occur. The method is applicable to encoding a region in the series where there is likely to be a cluster of non-zero-valued coefficients.
대표청구항
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The invention claimed is: 1. A method of operating an encoding apparatus, the apparatus configured to encode an ordered series of digital signals that each have a respective value, including a respective amplitude from a finite set of amplitudes consisting of the most likely-to-occur amplitude and
The invention claimed is: 1. A method of operating an encoding apparatus, the apparatus configured to encode an ordered series of digital signals that each have a respective value, including a respective amplitude from a finite set of amplitudes consisting of the most likely-to-occur amplitude and at least one other amplitude, the at least one other amplitude including a next most likely-to-occur amplitude to the most likely-to-occur amplitude, the method comprising: for a first contiguous region in the series: identifying runs that each includes one or more consecutive signals each having any amplitude other than the most likely-to-occur amplitude; and for each of at least some of the identified runs encoding the relative position and runlength of the identified run, and of any intervening consecutive signal having the most likely-to-occur amplitude; identifying amplitude events of at least one consecutive signal within the identified run, an identified amplitude event being (a) a sequence of at least one consecutive signal having the next most likely-to-occur amplitude that ends in a signal having other than the next most likely-to-occur amplitude, (b) only a signal having other than the next most likely-to-occur amplitude not preceded by a signal having the next most likely-to-occur amplitude, or (c) only a sequence of consecutive signals having the next most likely-to-occur amplitude not followed by a signal having other than the next most likely-to-occur amplitude, each identified amplitude event within the identified run defined by the length of the sequence of at least one consecutive signal having the next most likely-to-occur amplitude, and by the amplitude of the ending signal; and encoding each identified amplitude event by at least one codeword such that for at least some identified amplitude events, relatively more likely-to-occur amplitude events are encoded by shorter respective codewords than relatively less likely-to-occur amplitude events, such that relatively short codewords are formed to represent signal values or sequences of signal values that are relatively more likely-to-occur, and relatively long codewords are formed to represent signal values or sequences of signal values that are relatively less likely-to-occur. 2. A method as recited in claim 1, wherein the series of digital signals is a series of quantized coefficients of a transformed block of image data formed by a transform configured such that the most likely-to-occur amplitude is 0, and the next most likely-to-occur amplitude is 1, such that the step of identifying runs identifies runs that each includes a run with one or more non-zero-valued coefficients, and such that each identified amplitude event in an identified run includes a sequence of at least one consecutive coefficient of amplitude 1 that ends in an amplitude greater than 1, or a single coefficient of amplitude greater than 1, or a sequence of consecutive coefficients having only amplitude 1. 3. A method as recited in claim 2, wherein the identifying of amplitude events is for every identified run of non-zero coefficients in the series. 4. A method as recited in claim 2, wherein the identifying of amplitude events is for those identified runs of non-zero coefficients in the series that have a runlength less than or equal to a pre-selected length, the method further comprising: for the identified runs of consecutive non-zero coefficient having a runlength greater than the pre-selected length, for each identified run of the greater runlength, encoding the relative position and runlength of the identified run, and of any intervening consecutive coefficients having the most likely-to-occur amplitude; jointly encoding the non-zero amplitudes of the non-zero amplitudes by a multi-dimensional coding function of the amplitudes to produce a codeword such that for at least some runs of non-zero amplitudes, relatively more likely-to-occur amplitude runs are encoded by a shorter codeword than relatively less likely-to-occur amplitudes. 5. A method as recited in claim 2, wherein the transformed block of image data includes a DC term, and wherein the DC term is separately encoded, such that the series of digital signals is a set of non-DC quantized coefficients of a transformed block of image data. 6. A method as recited in claim 2, wherein the step of encoding each identified amplitude event includes separately encoding the signs of the amplitudes. 7. A method as recited in claim 2, wherein the step of encoding each identified amplitude event uses an encoding table that provides a codeword for each pair of the runlength of the sequence of preceding amplitude-1 coefficients and the amplitude of the ending coefficient of amplitude greater than 1, such that a different encoding table may be used for each runlength of an identified run of non-zero coefficients. 8. A method as recited in claim 7, wherein the coding table is constructed by assigning a variable length code according to measured or assumed statistics of amplitude events. 9. A method as recited in claim 2, wherein the step of identifying runs is part of a process that includes identifying a run of consecutive zero-valued coefficients preceding a run of one or more consecutive non-zero-valued coefficients followed by a single zero-valued coefficient, or identifying no zero-valued coefficients preceding a run of one or more consecutive non-zero-valued coefficients followed by a single zero-valued coefficient; and wherein the step of encoding the relative position and runlength of the identified run includes jointly encoding the runlengths of the preceding run of zero-valued coefficients and the following run of non-zero-valued coefficients, such that for at least some amplitude events, relatively more likely-to-occur pairs of runlengths are encoded by a shorter codeword than relatively less likely-to-occur runlengths. 10. A method as recited in claim 9, further comprising: providing a breakpoint to define the first contiguous region along the ordering of the series followed by a second contiguous region; such that the coefficients of the first contiguous region are encoded by a first encoding method that includes the step of identifying runs, the step of encoding the relative position and runlength, the step of identifying amplitude events, and the step of encoding each identified amplitude event; and encoding the coefficients in the second contiguous region using a second region encoding method, and wherein the first region encoding method and the second region encoding method are such that the encoding of at least some of the coefficients or runs of coefficients in the first contiguous region is different than the encoding of at least some of the coefficients or runs of coefficients in the second contiguous region. 11. A method as recited in claim 9, wherein the step of jointly encoding the runlengths uses a two-dimensional coding table. 12. A method as recited in claim 2, wherein the step of identifying runs includes determining the runlengths of one or more non-zero-valued coefficients followed by a single zero-valued coefficients, and determining the runlengths of any zero-valued coefficients preceding the runs of one or more non-zero-valued coefficients; and step of encoding the relative positions and runlengths of the identified runs includes: encoding the determined runlengths of the identified runs of non-zero-valued coefficients using a first runlength coding method, and encoding the determined runlengths of any preceding runs of zero-valued coefficients uses a second runlength coding method, such that for at least some amplitude events, relatively more likely-to-occur pairs of runlengths are encoded by a shorter codeword than relatively less likely-to-occur runlengths. 13. A computer readable storage hardware medium carrying machine readable code including instructions for performing, when executed by a processor, a method of processing an ordered series of digital signals that each have a respective value including a respective amplitude from a finite set of amplitudes consisting of the most likely-to-occur amplitude and at least one other amplitude the method comprising: for a first contiguous region in the series: identifying runs that each includes one or more consecutive signals having any amplitude other than the most likely-to-occur amplitude; for each identified run, identifying amplitude events of at least one consecutive signal, an identified amplitude event including a sequence of at least one consecutive signal having the next most likely-to-occur amplitude that ends in a signal having other than the next most likely-to-occur amplitude, or including only a signal of amplitude other than the next most likely-to-occur amplitude, or including a sequence of consecutive signals having only the next most likely-to-occur amplitude, each identified amplitude event for the length of the identified run defined by the length of the sequence of at least one consecutive signal having the next most likely-to-occur amplitude, and by the amplitude of the ending signal; and encoding each identified amplitude event by at least one codeword such that for at least some identified amplitude events, relatively more likely-to-occur amplitude events are encoded by a shorter codeword than relatively less likely-to-occur amplitude events, such that relatively short codewords are formed to represent signal values or sequences of signal values that are relatively more likely-to-occur, and relatively long codewords are formed to represent signal values or sequences of signal values that are relatively less likely-to-occur. 14. A computer readable hardware medium as recited in claim 13, wherein the series of digital signals is a series of quantized coefficients of a transformed block of image data formed by a transform such that the most likely-to-occur amplitude is 0, and the next most likely-to-occur amplitude is 1, such that the step of identifying amplitude events identifies amplitude events that each includes a run of one or more non-zero-valued coefficients. 15. A computer readable hardware medium as recited in claim 14, wherein the step of encoding each identified amplitude event includes separately encoding the signs of the amplitudes. 16. A computer readable hardware medium as recited in claim 14, wherein the encoding of the identified amplitude events, uses an encoding table that provides a codeword for each pair of the runlength of the sequence of preceding amplitude-1 coefficients and the amplitude of the ending coefficient of amplitude greater than 1, such that a different encoding table may be used for each runlength of an identified run of non-zero coefficients. 17. A hardware apparatus for processing an ordered series of digital signals that each have a respective value including a respective amplitude from a finite set of amplitudes consisting of the most likely-to-occur amplitude and at least one other amplitude, the apparatus comprising: means for identifying, in a first contiguous region in the series, runs that each includes one or more consecutive signals having any amplitude other than the most likely-to-occur amplitude; means for encoding the relative positions and runlengths of at least some of the identified runs of consecutive signals having any amplitude other than the most likely-to-occur amplitude and of any intervening consecutive coefficients having the most likely-to-occur amplitude; means for identifying amplitude events of at least one consecutive signal in each identified run, an identified amplitude event including a sequence of at least one consecutive signal having the next most likely-to-occur amplitude that ends in a signal having other than the next most likely-to-occur amplitude, or including only a signal of amplitude other than the next most likely-to-occur amplitude, or including a sequence of consecutive signals having only the next most likely-to-occur amplitude, each identified amplitude event for the length of the identified run defined by the length of the sequence of at least one consecutive signal having the next most likely-to-occur amplitude, and by the amplitude of the ending signal; and means for encoding each identified amplitude event by at least one codeword such that for at least some identified amplitude events, relatively more likely-to-occur amplitude events are encoded by a shorter codeword than relatively less likely-to-occur amplitude events, such that relatively short codewords are formed to represent values or sequences of values that are relatively more likely-to-occur, and relatively long codewords are formed to represent values or sequences of values that are relatively less likely-to-occur. 18. An apparatus as recited in claim 17, wherein the series of digital signals is a series of quantized coefficients of a transformed block of image data formed by a transform such that the most likely-to-occur amplitude is 0, and the next most likely-to-occur amplitude is 1, such that the means for identifying of amplitude events identifies amplitude events that each includes a run of one or more non-zero-valued coefficients. 19. An apparatus as recited in claim 18, wherein the means for identifying of amplitude events is for those identified runs of non-zero coefficients in the series that have a runlength less than or equal to a pre-selected length, the apparatus further comprising: for the identified runs of consecutive non-zero coefficient having a runlength greater than the pre-selected length, for each identified run of the greater runlength, means for encoding the relative position and runlength of the identified run, and of any intervening consecutive coefficients having the most likely-to-occur amplitude; means for jointly encoding the non-zero amplitudes of the non-zero amplitudes by a multi-dimensional coding function of the amplitudes to produce a codeword such that for at least some runs of non-zero amplitudes, relatively more likely-to-occur amplitude runs are encoded by a shorter codeword than relatively less likely-to-occur amplitudes, wherein the means for jointly encoding jointly encodes a plurality of amplitudes, and separately encodes the signs of the amplitudes. 20. An apparatus as recited in claim 18, wherein the means for encoding each identified amplitude event separately encodes the signs of the amplitudes. 21. An apparatus as recited in claim 18, wherein the means for encoding each identified amplitude event uses an encoding table that provides a codeword for each pair of runlengths of the sequence of preceding amplitude-1 coefficients and the amplitude of the ending coefficient of amplitude greater than 1, such that a different encoding table may be used for each runlength of an identified run of non-zero coefficients. 22. An apparatus including a processing system, the processing system including at least a processor and a memory, and configured to accept from the memory an ordered series of digital signals that each have a respective value including a respective amplitude from a finite set of amplitudes consisting of the most likely-to-occur amplitude and at least one other amplitude, the processing system configured to cause the apparatus to: for a first contiguous region in the series: identify runs that each includes one or more consecutive signals having any amplitude other than the most likely-to-occur amplitude; for each identified run, identify amplitude events of at least one consecutive signal, an identified amplitude event including a sequence of at least one consecutive signal having the next most likely-to-occur amplitude that ends in a signal having other than the next most likely-to-occur amplitude, or including only a signal of amplitude other than the next most likely-to-occur amplitude, or including a sequence of consecutive signals having only the next most likely-to-occur amplitude, each identified amplitude event for the length of the identified run defined by the length of the sequence of at least one consecutive signal having the next most likely-to-occur amplitude, and by the amplitude of the ending signal; and encode each identified amplitude event by at least one codeword such that for at least some identified amplitude events, relatively more likely-to-occur amplitude events are encoded by a shorter codeword than relatively less likely-to-occur amplitude events, such that relatively short codewords are formed to represent signal values or sequences of signal values that are relatively more likely-to-occur, and relatively long codewords are formed to represent signal values or sequences of signal values that are relatively less likely-to-occur. 23. An apparatus as recited in claim 22, wherein the series of digital signals is a series of quantized coefficients of a transformed block of image data formed by a transform such that the most likely-to-occur amplitude is 0, and the next most likely-to-occur amplitude is 1, such that the identifying of amplitude events identifies amplitude events that each includes a run of one or more non-zero-valued coefficients.
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