US6268939B1 — Method and apparatus for correcting luminance and…

Claim 1

Independent Claim 473 words

A method of correcting data in an input device dependent digital color image generated at an input device, preparatory to reproduction at a plural channel output device, comprising the steps of: a) providing input device dependent color image signals in an input device dependent color space said device dependent color image signals having been sub-sampled; b) providing information about the color response characteristic of the input device and the output device; c) using said information, mapping said input device dependent color image signals to output device dependent color image signals at said plurality of channels in an output device dependent color space, said output device dependent color space being an RGB space, with a complex mapping process which includes color correction, wherein said output device dependent color image signals correspond to said input device dependent color image signals said processing comprising: i) deriving a set of input device dependent master signals from said input device dependent color image signals by designating a signal set at a given location within each block wherein said input device dependent color imaging signals are received at three channels, wherein a first channel L receives luminance signals at a luminance channel resolution, a second channel Cr receives red-green chrominance signals at a red-green chrominance channel resolution, and a third channel Cb receives blue-yellow chrominance signals at a blue-yellow chrominance resolution; ii) mapping said input device dependent master signal set to an output device dependent master signal set in said output device dependent color space, said mapping comprising: dividing the digital color image into blocks, each block including a plurality of device dependent signal sets, wherein each signal set includes a signal from each of said channels, and wherein each block includes one master signal set; and applying a look up table conversion to transform said master signal set from said device dependent color space to said output device dependent color space; and iii) defining output device dependent color image signals corresponding to a subset of said input device dependent color signals, said defining step further comprises creating output device dependent signals for each signal set in said block according to a luminance signal for each signal set relative to a luminance of said master signal set; and wherein said creating step comprising: setting output device dependent signal Rij=(Rm/Lm)Lij; setting output device dependent signal Gij=(Gm/Lm)Lij; and setting output device dependent signal Bij=(Bm/Lm)Lij for each signal set Pij in said block, wherein ii denotes a location of each set within said block, Lij is said luminance signal of signal set Pij, Rm, Gm, and Bm are master signal set output device dependent signals and Lm is said master signal set luminance signal; and d) converting said output device dependent color image signals with a simple color conversion method to output device dependent coordinate signals which correspond to output device colorants.

Claim 2

Independent Claim 473 words

A method of correcting data in an input device dependent digital color image generated at an input device, preparatory to reproduction at a plural channel output device, comprising the steps of: a) providing input device dependent color image signals in an input device dependent color space said device dependent color image signals having been sub-sampled; b) providing information about the color response characteristic of the input device and the output device; c) using said information, mapping said input device dependent color image signals to output device dependent color image signals at said plurality of channels in an output device dependent color space, said output device dependent color space being an RGB space, with a complex mapping process which includes color correction, wherein said output device dependent color image signals correspond to said input device dependent color image signals said processing comprising: i) deriving a set of input device dependent master signals from said input device dependent color image signals by designating a signal set at a given location within each block wherein said input device dependent color imaging signals are received at three channels, wherein a first channel L receives luminance signals at a luminance channel resolution, a second channel Cr receives red-green chrominance signals at a red-green chrominance channel resolution, and a third channel Cb receives blue-yellow chrominance signals at a blue-yellow chrominance resolution; ii) mapping said input device dependent master signal set to an output device dependent master signal set in said output device dependent color space, said mapping comprising: dividing the digital color image into blocks, each block including a plurality of device dependent signal sets, wherein each signal set includes a signal from each of said channels, and wherein each block includes one master signal set; and applying a look up table conversion to transform said master signal set from said device dependent color space to said output device dependent color space; and iii) defining output device dependent color image signals corresponding to a subset of said input device dependent color signals, said defining step further comprises creating output device dependent signals for each signal set in said block according to a luminance signal for each signal set relative to a luminance of said master signal set; and wherein said creating step comprising: setting output device dependent signal Rij=(Rm/Lm)Lij; setting output device dependent signal Gij=(Gm/Lm)Lij; and setting output device dependent signal Bij=(Bm/Lm)Lij for each signal set Pij in said block, wherein ii denotes a location of each set within said block, Lij is said luminance signal of signal set Pij, Rm, Gm, and Bm are master signal set output device dependent signals and Lm is said master signal set luminance signal; and d) converting said output device dependent color image signals with a simple color conversion method to output device dependent coordinate signals which correspond to output device colorants.

Claim 3

Dependent Claim 51 words

A method of correcting data as claimed in claim 1 wherein said master signal set deriving step further comprises designating a pseudo-signal that has L channel, Cr channel, and Cb channel signals equal to the mean L channel, Cr channel, and Cb channel signals for all signal sets in said block.

Claim 4

Dependent Claim 25 words

A method of correcting data as claimed in claim 1 wherein said master signal set deriving step further comprises choosing a desired relative luminance signal.

Claim 5

Dependent Claim 26 words

A method of correcting data as claimed in claim 3 wherein said chosen luminance signal is a maximum signal of all luminance signals in said block.

Claim 6

Dependent Claim 27 words

A method of correcting data as claimed in claim 3 wherein said chosen luminance signal is nearest to an average for all luminance signals in said block.

Claim 7

Dependent Claim 107 words

A method of correcting data as claimed in claim 1 wherein said creating step further comprises: a) setting output device dependent signal Rij=a{circumflex over ( )}(loga Rm−loga Lm+loga Lij); b) setting output device dependent signal Gij=a{circumflex over ( )}(loga Gm−loga Lm+loga Lij); and c) setting output device dependent signal Bij=a{circumflex over ( )}(loga Bm−loga Lm+loga Lij) for each signal set Pij in said block, wherein ij denotes a location of each signal set within said block, Lij is said luminance signal of signal set Pij , Rm, Gm, and Bm are master signal set output device dependent signals and Lm is said master signal set luminance signal.

Claim 8

Dependent Claim 88 words

A method of correcting data as claimed in claim 1 wherein said creating step further comprises: a) setting output device dependent signal Rij=Rm−Lm+Lij b) setting output device dependent signal Gij=Gm−Lm+Lij; and c) setting output device dependent signal Bij=Bm−Lm+Lij for each signal set Pij in said block, wherein ij denotes a location of each signal set within said block, Lij is said luminance signal of signal set Pij, Rm, Gm, and Bm are master signal set output device dependent signals and Lm is said master signal set luminance signal.

Claim 9

Dependent Claim 21 words

A method of correcting data as claimed in claim 1 wherein said output device dependent color space is an LCrCb space.

Claim 10

Dependent Claim 119 words

A method of correcting data as claimed in claim 8 wherein said creating step further comprises: a) setting output device dependent signal L ij ′=(L m ′/L m )L ij ; b) setting output device dependent signal Cr ij ′=(L m ′/L m )Cr ij ; c) setting output device dependent signal Cb ij ′=(L m ′/L m )Cb ij ; for each signal set P ij in said block, wherein ij denotes a location of each set within said block, L ij is said device dependent luminance signal of signal set P ij , L m ′, is said master signal set output device dependent signal, and L m is said master signal set device dependent luminance signal.

Claim 11

Dependent Claim 22 words

A method of correcting data as claimed in claim 1 wherein an output device dependent color space is a CMYK color space.

Claim 12

Dependent Claim 142 words

A method of correcting data as claimed in claim 10 wherein said defining step further comprises: a) setting output device dependent coordinate signal C ij =1−((1−C m )/L m ) L ij ; b) setting output device dependent coordinate signal M ij =1−((1−M m )/L m )L ij ; c) setting output device dependent coordinate signal Y ij =1−((1−Y m )/L m )L ij ; and d) setting output device dependent coordinate signal K ij =K m , for each signal set P ij in said block, wherein ij denotes a location of each signal set within said block, L ij is said luminance signal of signal set P ij , C m , M m , Y m , and K m are master signal set device dependent color image signals and L m is a master signal set luminance signal.

Claim 13

Dependent Claim 34 words

A method of correcting data as claimed in claim 1 wherein said red-green channel resolution is less than said luminance channel resolution and said blue-yellow channel resolution is less than said red-green channel resolution.

Claim 14

Dependent Claim 93 words

A method of correcting data as claimed in claim 12 wherein said master signal deriving step further comprises: a) dividing the digital color image into a plurality of blocks, and further dividing said blocks into a plurality of sub-blocks, wherein each block includes a plurality of signal sets that have a substantially constant blue-yellow resolution, and each sub-block includes a plurality of signal sets that have substantially constant red-green chrominance and blue-yellow resolutions; b) selecting a master sub-block; and c) choosing a signal set within said master sub-block as said master signal set.

Claim 15

Dependent Claim 73 words

A method of correcting data as claimed in claim 13 wherein said mapping step further comprises: a) applying a look up table conversion to transform said master signal set from said device dependent color space to said output device dependent color space; b) correcting said output device dependent red-green chrominance signals for a subset of said sub-blocks; and c) correcting said output device dependent luminance signals for a subset of said signal sets.

Claim 16

Dependent Claim 28 words

A method of correcting data as claimed in claim 14 wherein said master sub-block selecting step further comprises designating a sub-block at a given location within each block.

Claim 17

Dependent Claim 46 words

A method of correcting data as claimed in claim 14 wherein said master sub-block selecting step further comprises creating a pseudo-sub-block that has L channel and Cr channel signals equal to the mean L channel and Cr channel signals for all signal sets in said block.

Claim 18

Dependent Claim 25 words

A method of correcting data as claimed in claim 14 wherein said master sub-block selecting step further comprises designating a desired relative red-green chrominance signal.

Claim 19

Dependent Claim 29 words

A method of correcting data as claimed in claim 17 wherein said designated red-green chrominance signal is a maximum magnitude of all chrominance red-green chrominance signals in said block.

Claim 20

Dependent Claim 29 words

A method of correcting data as claimed in claim 17 wherein said designated red-green chrominance signal is nearest to an average for all red-green chrominance signals in said block.

Claim 21

Dependent Claim 30 words

A method of correcting data as claimed in claim 14 wherein said master signal set choosing step further comprises designating a signal set at a given location within each sub-block.

Claim 22

Dependent Claim 25 words

A method of correcting data as claimed in claim 14 wherein said master signal set choosing step further comprises designating a desired relative luminance signal.

Claim 23

Dependent Claim 26 words

A method of correcting data as claimed in claim 21 wherein said designated luminance signal is a maximum signal of all luminance signals in said sub-block.

Claim 24

Dependent Claim 27 words

A method of correcting data as claimed in claim 21 wherein said designated luminance signal is nearest to an average for all luminance signals in said sub-block.

Claim 25

Dependent Claim 21 words

A method of correcting data as claimed in claim 14 wherein said output device dependent color space is an RGB space.

Claim 26

Dependent Claim 109 words

A method of correcting data as claimed in claim 24 wherein said red-green chrominance correcting step further comprises: a) setting L ij ′=L m ′(L ij /L m ); b) setting R ij ′=(R m /L m )L ij ; c) setting G ij ′=(G m /L m )L ij ; d) setting R ij ″=R ij′(Cr kl +Cr)/2Cr kl +G ij ′(Cr kl −Cr)/2Cr kl ; e) setting G ij ″=R ij ′(Cr kl −Cr)/2Cr kl +G ij ′(Cr kl +Cr)/2Cr kl , and f) setting B ij ″=B ij′ where Cr ij ′=R ij ′−G ij ′, and B ij ′=Cb ij ′+(R ij +G ij ′)/2.

Claim 27

Dependent Claim 46 words

A method of correcting data as claimed in claim 24 wherein said red-green chrominance correcting step further comprises: a) setting R ij ″=a**(Ir+Iplus−Idenom)+a**(Ig+Iminus−Idenom); and b) setting G ij ″=a**(Ir−Iplus+Idenom)+a**(Ig−Iminus+Idenom) where Iplus=log a [Cr kl +Cr], Iminus=log a [Cr kl −Cr], and Idenom=log a [2Cr kl ].

Claim 28

Dependent Claim 21 words

A method of correcting data as claimed in claim 14 wherein said output device dependent color space is an LCrCb space.

Claim 29

Dependent Claim 147 words

A method of correcting data as claimed in claim 27 wherein said red-green chrominance correcting step further comprises setting Crkl′=Crm′(Crkl/Crm) for each sub-block, and said luminance correcting step further comprises setting Lij′=Lm′(Lij/Lm) for each signal set, wherein kl denotes a location of each sub-block within said block, Crkl′ is an output device dependent red-green chrominance signal of sub-block Skl, Crm′ is an output device dependent red-green chrominance master signal, Crkl is a device dependent red-green chrominance signal of sub-block Ski, and Crm is a device dependent red-green chrominance master signal, and wherein ij denotes a location of each signal set within said block, Lij′ is an output device dependent luminance signal of signal set Pij, Lm′ is an output device dependent master signal set luminance signal, Lij is a device dependent luminance signal of signal set Pij, Lm is a device dependent master signal set luminance signal.

Claim 30

Dependent Claim 22 words

A method of correcting data as claimed in claim 14 wherein an output device dependent color space is a CMYK color space.

Claim 31

Dependent Claim 139 words

A method of correcting data as claimed in claim 29 wherein said defining step further comprises: a) setting output device dependent coordinate signal C ij =1−((1−C m )/L m )L ij ; b) setting output device dependent coordinate signal M ij =1−((1−M m )/L m )L ij ; c) setting output device dependent coordinate signal Y ij =1−((1−Y m )/L m )L ij ; and d) setting output device dependent coordinate signal K ij =K m , for each signal set P ij in said block, wherein ij denotes a location of each signal set within said block, L ij is said luminance signal of signalset P ij , C m , M m , Y m , and K m are master signal set device dependent color image signals and Lm is a master signal set luminance signal.

Claim 32

Independent Claim 486 words

An apparatus for correcting data in a device dependent digital color image generated at an input device, preparatory to reproduction at a plural channel output device, comprising: a) means for providing input device dependent color image signals in an input device dependent color space said device dependent color image signals having been sub-sampled; b) means for mapping said input device dependent color image signals to output device dependent color image signals at a plurality of channels in an output device dependent color space, said output device dependent color space being an RGB space, with a complex color mapping process which includes color correction said processing means further comprises: i) means for deriving a set of input device dependent master signals from said input device dependent color image signals by designating a signal set at a given location within each block wherein said input device dependent color imaging signals are received at three channels, wherein a first channel L receives luminance signals at a luminance channel resolution, a second channel Cr receives red-green chrominance signals at a red-green chrominance channel resolution, and a third channel Cb receives blue-yellow chrominance signals at a blue-yellow chrominance resolution; ii) means for mapping said input device dependent master signal set to an output device dependent master signal set in said output device dependent color space, said means for mapping comprising: means dividing the digital color image into blocks, each block including a plurality of device dependent signal sets, wherein each signal set includes a signal from each of said channels, and wherein each block includes one master signal set; and means for applying a look up table conversion to transform said master signal set from said device dependent color space to said output device dependent color space; and iii) means for defining output device dependent color image signals corresponding to a subset of said input device dependent color signals, said means for defining comprising means for creating output device dependent signals for each signal set in said block according to a luminance signal for each signal set relative to a luminance of said master signal set; and wherein said means for creating comprises: means for setting output device dependent signal Rij=(Rm/Lm)Lij; means for setting output device dependent signal Gij=(Gm/Lm)Lij; and means for setting output device dependent signal Bij=(Bm/Lm)Lij for each signal set Pij in said block, wherein ij denotes a location of each set within said block, Lij is said luminance signal of signal set Pij, Rm, Gm, and Bm are master signal set output device dependent signals and Lm is said master signal set luminance signal; and c) means for providing information about the color response characteristic of the input device and the output device, and d) means, using said information provided, for converting said output device dependent color image signals to output device dependent coordinate signals which correspond to output device colorants with a simple color space conversion method.

Claim 33

Independent Claim 486 words

An apparatus for correcting data in a device dependent digital color image generated at an input device, preparatory to reproduction at a plural channel output device, comprising: a) means for providing input device dependent color image signals in an input device dependent color space said device dependent color image signals having been sub-sampled; b) means for mapping said input device dependent color image signals to output device dependent color image signals at a plurality of channels in an output device dependent color space, said output device dependent color space being an RGB space, with a complex color mapping process which includes color correction said processing means further comprises: i) means for deriving a set of input device dependent master signals from said input device dependent color image signals by designating a signal set at a given location within each block wherein said input device dependent color imaging signals are received at three channels, wherein a first channel L receives luminance signals at a luminance channel resolution, a second channel Cr receives red-green chrominance signals at a red-green chrominance channel resolution, and a third channel Cb receives blue-yellow chrominance signals at a blue-yellow chrominance resolution; ii) means for mapping said input device dependent master signal set to an output device dependent master signal set in said output device dependent color space, said means for mapping comprising: means dividing the digital color image into blocks, each block including a plurality of device dependent signal sets, wherein each signal set includes a signal from each of said channels, and wherein each block includes one master signal set; and means for applying a look up table conversion to transform said master signal set from said device dependent color space to said output device dependent color space; and iii) means for defining output device dependent color image signals corresponding to a subset of said input device dependent color signals, said means for defining comprising means for creating output device dependent signals for each signal set in said block according to a luminance signal for each signal set relative to a luminance of said master signal set; and wherein said means for creating comprises: means for setting output device dependent signal Rij=(Rm/Lm)Lij; means for setting output device dependent signal Gij=(Gm/Lm)Lij; and means for setting output device dependent signal Bij=(Bm/Lm)Lij for each signal set Pij in said block, wherein ij denotes a location of each set within said block, Lij is said luminance signal of signal set Pij, Rm, Gm, and Bm are master signal set output device dependent signals and Lm is said master signal set luminance signal; and c) means for providing information about the color response characteristic of the input device and the output device, and d) means, using said information provided, for converting said output device dependent color image signals to output device dependent coordinate signals which correspond to output device colorants with a simple color space conversion method.

Claim 34

Dependent Claim 156 words

An apparatus for correcting data as claimed in claim 31 wherein said creating means further comprises: a) means for setting output device dependent signal R ij =a {circumflex over ( )}(log a Rm−log a L m +log a L ij ); b) means for setting output device dependent signal G ij =a {circumflex over ( )}(log a G m −log a L m +log a L ij ); and c) means for setting output device dependent signal B ij =a {circumflex over ( )}(log a B m −log a L m +log a L ij ) for each signal set P ij in said block, wherein ij denotes a location of each signal set within said block, L ij is said luminance signal of signal set P ij , R m , G m , and B m are master signal set output device dependent signals and L m is said master signal set luminance signal.

Claim 35

Dependent Claim 126 words

An apparatus for correcting data as claimed in claim 31 wherein said creating means further comprises: a) means for setting output device dependent signal R ij =R m −L m +L ij b) means for setting output device dependent signal G ij =G m −L m +L ij ; and c) means for setting output device dependent signal B ij =B m −L m +L ij for each signal set P ij in said block, wherein ij denotes a location of each signal set within said block, L ij is said luminance signal of signal set P ij , R m , G m , and B m are master signal set output device dependent signals and L m is said master signal set luminance signal.

Claim 36

Dependent Claim 125 words

An apparatus for correcting data as claimed in claim 31 wherein said creating means further comprises: a) means for setting output device dependent signal L ij ′=(L m ′/L m )L ij ; b) means for setting output device dependent signal Cr ij ′=(L m ′/L m )Cr ij ; c) means for setting output device dependent signal Cb ij ′=(L m ′/L m )Cb ij ; for each signal set P ij in said block, wherein ij denotes a location of each set within said block, L ij is said device independent luminance signal of signal set P ij , L m ′, is said master signal set output device dependent signal, and L m is said master signal set device independent luminance signal.

Claim 37

Dependent Claim 149 words

An apparatus for correcting data as claimed in claim 31 wherein said defining means further comprises: a) means for setting output device dependent coordinate signal C ij =1−((1−C m )/L m )L ij ; b) means for setting output device dependent coordinate signal M ij =1−((1−M m )/L m )L ij ; c) means for setting output device dependent coordinate signal Y ij =1−((1−Y m )/L m )L ij ; and d) means for setting output device dependent coordinate signal K ij =K m , for each signal set P ij in said block, wherein ij denotes a location of each signal set within said block, L ij is said luminance signal of signal set P ij , C m , M m , Y m , and K m are master signal set device dependent color image signals and L m is a master signal set luminance signal.

Claim 38

Dependent Claim 99 words

An apparatus for correcting data as claimed in claim 31 wherein said master signal deriving means further comprises: a) means for dividing the digital color image into a plurality of blocks, and further dividing said blocks into a plurality of sub-blocks, wherein each block includes a plurality of signal sets that have a substantially constant blue-yellow resolution, and each sub-block includes a plurality of signal sets that have substantially constant red-green chrominance and blue-yellow resolutions; b) means for selecting a master sub-block; and c) means for choosing a signal set within said master sub-block as said master signal set.

Claim 39

Dependent Claim 75 words

An apparatus for correcting data as claimed in claim 36 wherein said mapping means further comprises: a) means for applying a look up table conversion to transform said master signal set from said device independent color space to said output device dependent color space; b) correcting said output device dependent red-green chrominance signals for a subset of said sub-blocks; and c) correcting said output device dependent luminance signals for a subset of said signal sets.

Claim 40

Dependent Claim 123 words

An apparatus for correcting data as claimed in claim 37 wherein said red-green chrominance correcting means further comprises: a) means for setting L ij ′=L m ′(L ij /L m ); b) means for setting R ij ′=(R m /L m )L ij ; c) means for setting G ij ′=(G m /L m )L ij ; d) means for setting R ij ″=R ij ′(Cr kl +Cr)/2Cr kl +G ij ′(Cr kl −Cr)/2Cr kl ; e) means for setting G ij ″=R ij ′(Cr kl −Cr)/2Cr kl +G ij ′(Cr kl +Cr)/2Cr kl , and f) means for setting B ij ″=B ij ′ where Cr ij ′=R ij ′−G ij ′, and B ij ′=Cb ij ′+(R ij ′+G ij ′)/2.

Claim 41

Dependent Claim 50 words

An apparatus for correcting data as claimed in claim 37 wherein said red-green chrominance correcting means further comprises: a) means for setting R ij ″=a**(Ir+Iplus−Idenom)+a**(Ig+Iminus−Idenom); and b) means for setting G ij ″=a**(Ir−Iplus+Idenom)+a**(Ig−Iminus+Idenom) where Iplus=log a [Cr kl +Cr], Iminus=log a [Cr kl −Cr], and Idenom=log a [2Cr kl ].

Claim 42

Dependent Claim 185 words

An apparatus for correcting data as claimed in claim 37 wherein said red-green chrominance correcting means further comprises means for setting Cr kl ′=Cr m ′(Cr kl /Cr m ) for each sub-block, and said luminance correcting means further comprises means for setting L ij ′=L m ′(L ij /L m ) for each signal set, wherein kl denotes a location of each sub-block within said block, Cr kl ′ is an output device dependent red-green chrominance signal of sub-block Ski, Cr m ′ is an output device dependent red-green chrominance master signal, Cr kl is a device independent red-green chrominance signal of sub-block S kl , and Cr m is a device independent red-green chrominance master signal, and wherein ij denotes a location of each signal set within said block, L ij ′ is an output device dependent luminance signal of signal set P ij , L m ′ is an output device dependent master signal set luminance signal, L ij is a device independent luminance signal of signal set P ij , L m is a device independent master signal set luminance signal.

Claim 43

Dependent Claim 149 words

An apparatus for correcting data as claimed in claim 37 wherein said defining means further comprises: a) means for setting output device dependent coordinate signal C ij =1−((1−C m )/L m )L ij ; b) means for setting output device dependent coordinate signal M ij =1−((1−M m )/L m )L ij ; c) means for setting output device dependent coordinate signal Y ij =1−((1−Y m )/L m )L ij ; and d) means for setting output device dependent coordinate signal K ij =K m , for each signal set P ij in said block, wherein ij denotes a location of each signal set within said block, L ij is said luminance signal of signal set P ij , C m , M m , Y m , and K m are master signal set device dependent color image signals and L m is a master signal set luminance signal.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2004-07-30	2005-01-29	2005-07-31	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2008-07-30	2009-01-29	2009-07-31	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2012-07-30	2013-01-29	2013-07-31	$7700.00	Window Closed / Lapsed

Method and apparatus for correcting luminance and chrominance data in digital color images

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