A method for digital image compression using Discrete Wavelet Transform DWT

Claim 2

The method according to claim 1, wherein said transforming step includes applying a discrete wavelet transform to said digital image.

Claim 4

The method according to claim 2, wherein in said portion includes a subband of said plurality of coefficients.

Claim 5

The method according to claim 1, wherein said first and second tokens include bit values of 0 and 1, respectively.

Claim 6

The method according to claim 1, wherein said subregions are equally sized.

Claim 7

The method according to claim 6, wherein said subregions are square.

Claim 8

The method according to claim 1, wherein said predetermined size of said subregion is less than or equal to 2×2 coefficients.

Claim 9

The method according to claim 8, wherein coefficients of said predetermined size subregion are encoded by outputting bits of said corresponding bit sequence beginning with the respective significant bitplane.

Claim 10

The method according to claim 9, wherein only bits of said corresponding bit sequence above said predetermined minimum bit level are output in said coded representation.

Claim 11

The method according to claim 1, wherein, in step (c), steps (a) and (b) are repeated otherwise until each bitplane of said selected region has been scanned.

Claim 12

The method according to claim 11, wherein each bitplane of said selected region above said minimum bit level has been scanned.

Claim 14

The apparatus according to claim 13, wherein said transforming means includes means for applying a discrete wavelet transform to said digital image.

Claim 16

The apparatus according to claim 14, wherein in said portion includes a subband of said plurality of coefficients.

Claim 17

The apparatus according to claim 13, wherein said first and second tokens include bit values of 0 and 1, respectively.

Claim 18

The apparatus according to claim 13, wherein said subregions are equally sized.

Claim 19

The apparatus according to claim 18, wherein said subregions are square.

Claim 20

The apparatus according to claim 13, wherein said predetermined size of said subregion is less than or equal to 2×2 coefficients.

Claim 21

The apparatus according to claim 20, wherein coefficients of said predetermined size subregion are encoded by outputting bits of said corresponding bit sequence beginning with the respective significant bitplane.

Claim 22

The apparatus according to claim 21, wherein only bits of said corresponding bit sequence above said predetermined minimum bit level are output in said coded representation.

Claim 23

The apparatus according to claim 13, wherein said control means controls said scanning and partitioning means to repetitively function until each bitplane of said selected region has been scanned.

Claim 24

The apparatus according to claim 23, wherein each bitplane of said selected region above said minimum bit level has been scanned.

Claim 25

The apparatus according to claim 13, wherein said apparatus is implemented using a general-purpose digital computer.

Claim 26

A computer program product including a computer readable medium having recorded thereon a computer program for representing a digital image to provide a coded representation, said computer program product comprising: means for transforming said digital image to derive a plurality of coefficients, each coefficient represented by a predefined bit sequence; means for selecting a portion of said plurality of coefficients as a region; means for scanning the significance of each bitplane of said selected region from a most significant bitplane towards a least significant bitplane, and providing a first token for each insignificant bitplane and a second token for a significant bitplane in said coded representation until a significant bitplane is determined; means for partitioning said selected region into two or more subregions having a predetermined form, and setting each of said subregions as said selected region; means for controlling said scanning means and said partitioning means to carry out respective functioning of said scanning and partitioning means commencing from said significant bitplane until said selected region has a predetermined size or a predetermined minimum bit level has been reached, wherein said coefficients of said selected region are coded and provided in said coded representation.

Claim 27

The computer program product according to claim 26, wherein said transforming means includes means for applying a discrete wavelet transform to said digital image.

Claim 28

The computer program product according to claims 26, wherein said region includes said entire plurality of coefficients.

Claim 29

The computer program product according to claim 27, wherein in said portion includes a subband of said plurality of coefficients.

Claim 30

The computer program product according to claim 26, wherein said first and second tokens include bit values of 0 and 1, respectively.

Claim 31

The computer program product according to claim 26, wherein said subregions are equally sized.

Claim 32

The computer program product according to claim 31, wherein said subregions are square.

Claim 33

The computer program product according to claim 26, wherein said predetermined size of said subregion is less than or equal to 2×2 coefficients.

Claim 34

The computer program product according to claim 33, wherein coefficients of said predetermined size subregion are encoded by outputting bits of said corresponding bit sequence beginning with the respective significant bitplane.

Claim 35

The computer program product according to claim 34, wherein only bits of said corresponding bit sequence above said predetermined minimum bit level are output in said coded representation.

Claim 36

The computer program product according to claim 26, wherein said control means controls said scanning and partitioning means to repetitively function until each bitplane of said selected region has been scanned.

Claim 37

The computer program product according to claim 36, wherein each bitplane of said selected region above said minimum bit level has been scanned.

Claim 38

The computer program product according to claim 26, wherein said computer program product is implemented using a general-purpose computer.

Claim 39

The computer program product according to claim 38, wherein said computer program product includes a set of instructions executable on said computer, wherein said set of instructions includes modules for implementing said transforming means, said selecting means, said scanning means, said partitioning means, and said controlling means.

Claim 41

The method according to claim 40, further comprising the step of inverse transforming decoded coefficients of said output stream to provide said digital image.

Claim 42

The method according to claim 41, wherein said inverse transforming step includes the step of applying an inverse discrete wavelet transform to said decoded coefficients.

Claim 43

The method according to claim 40, wherein said predetermined size is less than or equal to 2×2 coefficients.

Claim 44

The method according to claim 40, wherein each coefficient is to be represented by a predefined bit sequence, and said predetermined size coded coefficients are decoded by outputting bits of said corresponding bit sequence beginning with the respective significant bitplane.

Claim 45

The method according to claim 44, wherein only bits of said corresponding bit sequence above said predetermined minimum bit level are output in said output stream.

Claim 46

The method according to claim 40, wherein, in step (d), steps (a) to (c) are repeated otherwise until each bitplane of said selected region has been scanned.

Claim 47

The method according to claim 40, wherein said scanning step is performed from a most significant bitplane towards a least significant bitplane, and said predetermined bitplane is said significant bitplane.

Claim 49

The apparatus according to claim 48, further comprising means for inverse transforming decoded coefficients of said output stream to provide said digital image.

Claim 50

The apparatus according to claim 49, wherein said inverse transforming means includes means for applying an inverse discrete wavelet transform to said decoded coefficients.

Claim 51

The apparatus according to claim 48, wherein said predetermined size is less than or equal to 2×2 coefficients.

Claim 52

The apparatus according to claim 48, wherein each coefficient is to be represented by a predefined bit sequence, and said predetermined size coded coefficients are decoded by outputting bits of said corresponding bit sequence beginning with the respective significant bitplane.

Claim 53

The apparatus according to claim 52, wherein only bits of said corresponding bit sequence above said predetermined minimum bit level are output in said output stream.

Claim 54

The apparatus according to claim 48, wherein said controlling means controls said scanning means, said means for providing said insignificant birplane, and means for providing said significant bitplane to repetitively function until each bitplane of said selected region has been scanned.

Claim 56

The apparatus according to claim 48, wherein said scanning means scans from a most significant bitplane towards a least significant bitplane, and said predetermined bitplane is said significant bitplane.

Claim 57

A computer program product including a computer readable medium having recorded thereon a computer program for decoding a coded representation of a digital image, said computer program product comprising: means for selecting a region of coefficients of said coded representation of said digital image, said coded representation including a first token for each insignificant bitplane of said coefficients, a second token for each significant bitplane of said coefficients, and zero or more coded coefficients; means for scanning said coded representation of said selected region; means for, if a first token is determined, providing an insignificant bitplane in an output stream for a current bitplane of coefficients of said selected region; means for, if a second token is determined, providing a significant bitplane in said output stream for said current bitplane of said coefficients of said selected region and partitioning said selected region into two or more subregions having a predetermined form, and setting each of said subregions as said selected region; means for controlling said scanning means, said means for providing said insignificant bitplane, and said means for providing said significant bitplane commencing from a predetermined bitplane until a predetermined minimum bit level has been reached, or until said selected region has a predetermined size wherein a coded coefficient of said selected region is decoded and provided in said output stream.

Claim 58

The computer program product according to claim 57, further comprising means for inverse transforming decoded coefficients of said output stream to provide said digital image.

Claim 59

The computer program product according to claim 57, wherein said inverse transforming means includes means for applying an inverse discrete wavelet transform to said decoded coefficients.

Claim 60

The computer program product according to claim 57, wherein said predetermined size is less than or equal to 2×2 coefficients.

Claim 61

The computer program product according to claim 57, wherein each coefficient is to be represented by a predefined bit sequence, and said predetermined size coded coefficients are decoded by outputting bits of said corresponding bit sequence beginning with the respective significant bitplane.

Claim 62

The computer program product according to claim 61, wherein only bits of said corresponding bit sequence above said predetermined minimum bit level are output in said output stream.

Claim 63

The computer program product according to claim 57, wherein said controlling means controls said scanning means, said means for providing said insignificant bitplane, and means for providing said significant bitplane to repetitively function until each bitplane of said selected region has been scanned.

Claim 64

The computer program product according to claims 57, wherein said computer program product is implemented using a general-purpose digital computer.

Claim 65

The computer program product according to claim 64, wherein said computer program product includes a set of instructions executable on said computer, wherein said set of instructions includes modules for implementing said selecting means, said scanning means, said means for providing said insignificant bitplane, said means for providing said significant bitplane, and said controlling means.

Claim 66

The computer program product according to claim 57, wherein said scanning means scans from a most significant bitplane towards a least significant bitplane, and said predetermined bitplane is said significant bitplane.

Claim 68

The method according to claim 67, wherein said coefficients of said selected region are coded by representing each coefficient by the bits between the corresponding current bit level and the minimum bit level.

Claim 69

The method according to claim 67, wherein said subband transform includes a discrete wavelet transform.

Claim 71

The apparatus according to claim 70, wherein said coefficients of said selected region are coded by representing each coefficient by the bits between the corresponding current bit level and the minimum bit level.

Claim 72

The apparatus according to claim 70, wherein said subband transform includes a discrete wavelet transform.

Claim 73

A computer program product including a computer readable medium having recorded thereon a computer program for encoding a digital image, said computer program product including: means for decomposing said image using a subband transform to provide a number of subbands; means for, for each subband, selecting said subband as an initial region and including the following: means for checking if a current bit level of the selected region is significant; means for, if said current bit level is significant, outputting a first token in a coded representation and partitioning said selected region into a number of equally sized sub-regions, wherein each sub-region is processed as said selected region in turn; means for, if said current bit level is insignificant, outputting a second token in said coded representation and selecting the next lower bit level of said selected region as said current bit level; and means for controlling said checking means, said means for outputting said first token, and said means for outputting said second token to carry out respective functioning of said checking means, said means for outputting said first token, and said means for outputting said second token until said current bit level is less than a specified minimum bit level, or said selected region has a predetermined size wherein coefficients of said selected region are coded in said coded representation.

Claim 74

The computer program product according to claim 73, wherein said coefficients of said selected region are coded by representing each coefficient by the bits between the corresponding current bit level and the minimum bit level.

Claim 75

The computer program product according to claim 73, wherein said subband transform includes a discrete wavelet transform.

Claim 77

The method according to claim 76, further comprising the step of inverse decomposing said decoded subbands using an inverse subband transform to provide said digital image.

Claim 78

The method according to claim 76, wherein said coded coefficients are represented by the bits between said corresponding current bit level and said specified minimum bit level.

Claim 79

The method according to claim 77, wherein said inverse subband transform includes an inverse discrete wavelet transform.

Claim 81

The apparatus according to claim 80, further comprising the step of inverse decomposing said decoded subbands using an inverse subband transform to provide said digital image.

Claim 82

The apparatus according to claim 80, wherein said coded coefficients are represented by the bits between said corresponding current bit level and said specified minimum bit level.

Claim 83

The apparatus according to claim 81, wherein said inverse subband transform includes an inverse discrete wavelet transform.

Claim 84

A computer program product including a computer readable medium having recorded thereon a computer program for decoding a coded representation of a digital image, said computer program product including: means for, for each region of said coded representation corresponding to a subband, selecting a region of coefficients of said coded representation as an initial region, said coded representation containing a first token for each significant bit level, a second token for each insignificant bit level, and zero or more coded coefficients, each region comprising at least one coefficient, and further including: means for checking a current bit level of said selected region of said coded representation for a token; means for, if said current bit level has a first token, outputting a significant bit level and partitioning said selected region into a number of equally sized sub-regions, wherein each sub-region is processed as said selected region in turn; means for, if said current bit level has a second token, outputting an insignificant bit level and selecting the next lower bit level of said selected region as said current bit level; means for controlling repeated functioning of said checking means, said partitioning means, and said means for selecting the next lower bit level until said current bit level is less than a specified minimum bit level, or said selected region has a predetermined size wherein at least one coded coefficient of said selected region is decoded for providing a subband for said selected region.

Claim 85

The computer program product according to claim 84, further comprising means for inverse decomposing said decoded subbands using an inverse subband transform to provide said digital image.

Claim 86

The computer program product according to claim 84, wherein said coded coefficients are represented by the bits between said corresponding current bit level and said specified minimum bit level.

Claim 87

The computer program product according to claim 85, wherein said inverse subband transform includes an inverse discrete wavelet transform.

Claim 89

The method according to claim 88, further including the step of dividing the digital image into a plurality of blocks, said blocks being subband transformed to provide said plurality of AC subband regions and said DC subband region.

Claim 90

The method according to claim 88, further including the step of dividing subband transform coefficients of said digital image into a plurality of blocks to provide said plurality of AC subband regions and said DC subband region.

Claim 92

The apparatus according to claim 91, further including: means for dividing the digital image into a plurality of blocks; and means for subband transforming said blocks to provide said plurality of AC subband regions and said DC subband region.

Claim 93

The apparatus according to claim 91, further including: means for subband transforming said blocks to provide said plurality of AC subband regions and said DC subband region; and means for dividing subband transform coefficients into a plurality of blocks to provide said plurality of AC subband regions and said DC subband region.

Claim 94

A computer program product including a computer readable medium having recorded thereon a computer program for encoding a digital image, said computer program product including: means for applying a subband transform to said digital image to provide a plurality of AC subband regions, at one or more resolutions, and a DC subband region for each block; means for selecting said DC subband region as a selected region, and further including: means for checking if a current bitplane of the selected region is significant; means for, if said current bitplane is significant, outputting a first token in a coded representation and partitioning said selected region into a number of sub-regions, wherein each sub-region is processed as the selected region in turn; means for, if said current bitplane is insignificant, outputting a second token in the coded representation and selecting the next lower bitplane of the selected region as the current bitplane; means for controlling repeated operation of said checking means, said first token outputting means, and said second token outputting means until said current bitplane is less than a specified minimum bitplane, or said selected region has a predetermined size and coefficients of said selected region are coded in said coded representation; means for selecting substantially all uncoded AC subband regions as a remaining region of each block and scanning the significance of each bitplane of the remaining region from a most significant bitplane towards a least significant bitplane, and outputting the second token for each insignificant bitplane until a significant bitplane is determined; means for setting one or more AC subband regions, of a current resolution level, as a selected region and further including: means for checking if a current bitplane of the selected region is significant; means for, if said current bitplane is significant, outputting said first token in a coded representation and partitioning said selected region into a number of sub-regions, wherein each sub-region is processed as the selected region in turn; means for, if said current bitplane is insignificant, outputting said second token in the coded representation and selecting the next lower birplane of the selected region as the current bitplane; means for controlling repeated operation of said checking means. said first token outputting means, and said second token outputting means until said current bitplane is less than a specified minimum bitplane, or said selected region has a predetermined size and coefficients of said selected region are coded in said coded representation; means for controlling repeated operation of said AC-subband-region setting means until substantially all AC subbands of the current resolution level have been encoded; and means for controlling repeated operation of said uncoded-AC-subband-regions selecting means, said AC-subband-region setting means, and said means for controlling said AC-subband-region setting means until all AC subbands of each block have been encoded.

Claim 95

The apparatus according to claim 94, further including: means for dividing the digital image into a plurality of blocks; and means for subband transforming said blocks to provide said plurality of AC subband regions and said DC subband region.

Claim 96

The apparatus according to claim 94, further including: means for subband transforming said blocks to provide said plurality of AC subband regions and said DC subband region; and means for dividing subband transform coefficients into a plurality of blocks to provide said plurality of AC subband regions and said DC subband region.

Claim 98

The method according to claim 97, further including the step of applying an inverse subband transform to said plurality of decoded AC subband regions, at one or more resolutions, and said decoded DC subband region for each block to provide said digital image.

Claim 100

The apparatus according to claim 99, further including means for applying an inverse subband transform to said plurality of decoded AC subband regions, at one or more resolutions, and said decoded DC subband region for each block to provide said digital image.

Claim 101

A computer program product including a computer readable medium having recorded thereon a computer program for decoding a coded representation of a digital image, said computer program product including: means for selecting a region of said coded representation corresponding to said DC subband region as a selected region, said selecting means further including: means for checking if a current bitplane of the selected region contains a first or second token; means for, if a first token is found, outputting a significant bitplane and partitioning said selected region into a number of sub-regions, wherein each sub-region is processed as the selected region in turn; means for, if a second token is found, outputting an insignificant bitplane and selecting the next lower bitplane of the selected region as the current bitplane; means for controlling repeated operation of said checking means, said significant-bitplane outputting means, and said insignificant-bitplane outputting means until said current bitplane is less than a specified minimum bitplane, or said selected region has a predetermined size and coded coefficients of said selected region are decoded; means for selecting a remaining region of said coded representation corresponding to substantially all uncoded AC subband regions and checking each bitplane of the remaining region of each block from a most significant bitplane towards a least significant bitplane for a first or second token, and outputting an insignificant bitplane for each second token until a first token is determined; means for outputting a significant bitplane and setting one or more regions of said coded representation corresponding to AC subband regions, of a current resolution level, as a selected region, said outputting and setting means further including: means for checking if a current bitplane of the selected region contains a first or second token; means for, if a first token is found, outputting a significant bitplane and partitioning said selected region into a number of sub-regions, wherein each sub-region is processed as the selected region in turn; means for, if a second token is found, outputting an insignificant bitplane and selecting the next lower bitplane of the selected region as the current bitplane; means for controlling repeated operation of said checking means, said significant-bitplane outputting means, and said insignificant-bitplane outputting means until said current bitplane is less than a specified minimum bitplane, or said selected region has a predetermined size and coded coefficients of said selected region are decoded; means for controlling repeated operation of said setting and outputting means until substantially all regions of said coded representation corresponding to AC subbands of the current resolution level have been decoded; and means for controlling repeated operation of said means for selecting a remaining region of said coded representation corresponding to substantially all uncoded AC subband regions, said means for outputting a significant bitplane and setting one or more regions of said coded representation corresponding to AC subband regions, and means for controlling repeated operation of said setting and outputting means until all regions of said coded representation corresponding to said AC subbands of each block have been decoded.

Claim 102

The apparatus according to claim 101, further including means for applying an inverse subband transform to said plurality of decoded AC subband regions, at one or more resolutions, and said decoded DC subband region for each block to provide said digital image.

Claim 107

A computer program product including a computer readable medium having recorded thereon a computer program for encoding a digital image, said computer program product being substantially as hereinbefore described with reference to either Figs. 3 to 7, or Figs 9 to 12, in combination to Figs. 1, 2, 8 and 13 of the accompanying drawings.

Claim 108

A computer program product including a computer readable medium having recorded thereon a computer program for decoding a coded representation of a digital image, said computer program product being substantially as hereinbefore described with reference to either Figs. 3 to 7, or Figs 9 to 12, in combination to Figs. 1, 2, 8 and 13 of the accompanying drawings.

Claim 109

A storage device storing computer readable instructions for causing a programmable processing apparatus to perform a method as claimed in any one of claims 40 to 47 or any one of claims 67 to 69 or any one of claims 76 to 79 or any one of claims 88 to 90 or any one of claims 97 and 98.