(12) United States Patent
`(12) United States Patent
`Meyers et al.
`Meyers et al.
`
`US006486889B1
`US006486889B1
`US 6,486,889 B1
`(io) Patent No.:
`(10) Patent N68
`US 6,486,889 B1
`(45) Date of Patent:
`Nov. 26,2002
`(45) Date of Patent:
`Nov. 26, 2002
`
`(54) METHODS AND APPARATUS FOR
`(54) METHODS AND APPARATUS FOR
`TRANSFORMING RGB VIDEO
`TRANSFORMING RGB VIDEO
`
`(75) Inventors: Michael Edward Meyers, Fairport, NY
`Inventors: Michael Edward Meyers, Fairport, NY
`(75)
`(US); Whynn Victor Lovette, Ontario,
`(Us); Whynn Victor Lovell‘? Ontari9>
`NY (US); John Stewart Ceci, Penfield,
`NY (Us); John Stewart Cecl> Pen?e1d>
`NY (US); Brian C. Hawkins,
`NY (Us); Brian C- Hawkins,
`Rochester, NY (US)
`Rochesten NY (Us)
`(73) Assignee: Xerox Corporation, CT (US)
`(73) Assignee: Xerox Corporation, CT (US)
`
`( * ) Notice:
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`patent is extended or adjusted under 35
`USC 154(b) by 0 days,
`U.S.C. 154(b) by 0 days.
`
`.
`
`..
`
`,
`
`(21) Appl NO . 09/466 182
`(21) Appl. No.: 09/466,182
`(22) Filed:
`Dec. 17, 1999
`Dec. 17, 1999
`(22) Filed:
`.. G09G 5/04
`(51) Int. CI.7
`(51) Int. c1.7 ................................................ .. G09G 5/04
`(52) us CL
`345/604
`345/604
`(52) U.S. CI
`(58) Field of
`.................................... "515/602 604
`(58) Field of Search
`345/602, 604
`"""""""""""""""" "
`’
`References Cited
`References Cited
`U.S. PATENT DOCUMENTS
`U.S. PATENT DOCUMENTS
`
`(56)
`(56)
`
`348/385
`5,455,626 A * 10/1995 Xu et al
`5,455,626 A * 10/1995 Xu et a1. .................. .. 348/385
`382/167
`5,504,821 A * 4/1996 Kanamori et al.
`5,504,821 A * 4/1996 Kanamori et al. ........ .. 382/167
`5,519,441 A
`5/1996 Gusmano et al.
`5,519,441 A
`5/1996 Gusmano et a1.
`
`6,340,975 B2 * 1/2002 Marsden et al.
`.... 345/590
`6,340,975 132 * 1/2002 Marsden a a1. .......... .. 345/590
`6,256,350 B1 * 7/2002 Bishay et al. ..
`375/240.21
`6,256,350 B1 * 7/2002 Bishay et al. ........ .. 375/240.21
`OTHER PUBLICATIONS
`OTHER PUBLICATIONS
`Michael Stokes et al.,"A Standard Default Color Space for
`Michael Stokes et al.,“A Standard Default Color Space for
`the Internet—sRGB," Version 1.10, Nov. 5, 1996: http://
`the Internet—sRGB,” Version 1.10, Nov. 5, 1996: http://
`www.w3.org/Graphics/Color/sRGB.
`WWW.W3.org/Graphics/Color/sRGB.
`Eric Hamilton, "JPEG File Interchange Format," Version
`Eric Hamilton, “JPEG File Interchange Format,” Version
`1.02, Sep. 1, 1992: http://www.w3.org/Graphics/JPEG/
`1.02, Sep. 1, 1992: http://WWW.W3.org/Graphics/JPEG/
`j?f'txt'
`jfif.txt.
`
`* cited by examiner
`* Cited by examiner
`
`Primary Examiner—Jeffery Brier
`Primary Examiner—Jeffery Brier
`Assistant Examiner—G. F. Cunningham
`Assistant Examiner—G. F. Cunningham
`(74) Attorney, Agent, or Firm—Oliff & Berridge PLC
`(74) Attorney, Agent, or Firm—Oliff & Berridge PLC
`ABSTRACT
`(57)
`(57)
`ABSTRACT
`Apparatus and methods in accordance with an exemplary
`Apparatus and methods in accordance With an exemplary
`embodiment of the invention convert RGB video to at least
`embodiment of the invention convert RGB video to at least
`one video output of Lab video, YCbCr video, with or
`one Video Output of Lab Video, Ycbcr Video, With or
`without gamma correction, and Srgb video, with or without
`Without gamma correction, and Srgb video, With or Without
`gamma correction. This conversion increases the flexibility
`gamma correction. This conversion increases the ?exibility
`of image information communication by enabling RGB
`of image information communication by enabling RGB
`video to be provided to a device that can only handle one of
`video to be provided to a device that can only handle one of
`Lab, Srgb and/or YCbCr video.
`Lab’ Srgb and/OrYcbCr Vldeo'
`
`26 Claims, 1 Drawing Sheet
`26 Claims, 1 Drawing Sheet
`
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`front and
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`US 6,486,889 B1
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`front end coefficients
`
`

`
`US 6,486,889 B1
`US 6,486,889 B1
`
`BACKGROUND OF THE INVENTION
`BACKGROUND OF THE INVENTION
`
`X=(ie coefficient 0)/?+(fe coefficient l)G+(fe coefficient 2) B;
`
`y=(fe_coefficient 3)i?+(fe_coefficient 4)G+(fe_coefficient 5) B;
`
`1
`1
`METHODS AND APPARATUS FOR
`METHODS AND APPARATUS FOR
`TRANSFORMING RGB VIDEO
`TRANSFORMING RGB VIDEO
`
`2
`2
`FIG. 1, an input 100 of RGB video is converted to at least
`FIG. 1, an input 100 of RGB video is converted to at least
`one video output 1000 of at least one of Lab video, YCbCr
`one video output 1000 of at least one of Lab video, YCbCr
`video, with or without gamma correction, and Srgb video
`video, With or Without gamma correction, and Srgb video
`(scanner independent RGB), with or without gamma
`(scanner independent RGB), With or Without gamma
`5 correction, by the exemplary embodiment of the methods
`correction, by the exemplary embodiment of the methods
`and apparatus of the invention. This exemplary conversion
`and apparatus of the invention. This exemplary conversion
`1. Field of Invention
`1. Field of Invention
`is discussed in detail below.
`is discussed in detail beloW.
`The invention relates to color space transformation of
`The invention relates to color space transformation of
`The input 100, which includes three channels of 9 bit
`The input 100, Which includes three channels of 9 bit
`RGB video.
`RGB video.
`RGB video, is provided to a front end 3x3 multiplier 10.
`RGB video, is provided to a front end 3x3 multiplier 10.
`2. Description of Related Art
`2. Description of Related Art
`1° Thirteen bit front end coefScients, which can be
`10
`Thirteen bit front end coef?cients, Which can be
`Data relating to color information, such as color images,
`programmable, are also provided to the multiplier 10. The
`Data relating to color information, such as color images,
`programmable, are also provided to the multiplier 10. The
`can be communicated to a broad range of devices, such as,
`multiplier 10 then performs a matrix multiply using the input
`multiplier 10 then performs a matrix multiply using the input
`can be communicated to a broad range of devices, such as,
`for example, cathode ray tube monitors, televisions,
`100 and the front end coefScients.
`for example, cathode ray tube monitors, televisions,
`100 and the front end coef?cients.
`xhe muitipiy performed by the multiplier 10 can be
`scanners, digital cameras and printers. However, these
`scanners, digital cameras and printers. HoWever, these
`The multiply performed by the multiplier 10 can be
`devices typically utilize numerous different formats and 15 expressed as follows'
`devices typically utiliZe numerous different formats and
`15
`expressed as folloWs:
`methods of handling the color information. Thus, color
`methods of handling the color information. Thus, color
`information communicated to a certain device may not be in
`information communicated to a certain device may not be in
`the appropriate format to be utilized by that device. Com­
`the appropriate format to be utiliZed by that device. Com
`municating improperly formatted color information may
`municating improperly formatted color information may
`result in the device incorrectly mapping the color informa- 20
`result in the device incorrectly mapping the color informa
`tion or even the device being unable to utilize the color
`tion or even the device being unable to utiliZe the color
`information at all.
`information at all.
`
`Z=(fe coefficient 6)i?+(fe coefficient 7)G+(fe coefficient 8) B;
`
`SUMMARY OF THE INVENTION
`wherein: fe coefScients (0-8) are the programmable front
`Wherein: feicoef?cients (0—8) are the programmable front
`SUMMARY OF THE INVENTION
`25 end coefScients, RGB are three input video components of
`end coef?cients, RGB are three input video components of
`25
`It is therefore desirable to enable a device, that is only able
`It is therefore desirable to enable a device, that is only able
`the input 10, and XYZ are three outputs of the multiplier 10.
`the input 10, and XYZ are three outputs of the multiplier 10.
`to handle a specified format of color information, to handle
`to handle a speci?ed format of color information, to handle
`The outputs 200 of the front end 3x3 multiplier 10 will,
`The outputs 200 of the front end 3x3 multiplier 10 Will,
`another format of color information that is at least initially
`another format of color information that is at least initially
`under normal circumstances, represent one of two possible
`under normal circumstances, represent one of tWo possible
`different from the specified format. In other words, it is
`different from the speci?ed format. In other Words, it is
`cases. If the RGB input 100 is being converted to Lab, the
`cases. If the RGB input 100 is being converted to Lab, the
`desirable to enable the communication of a first format of
`desirable to enable the communication of a ?rst format of
`30 outputs 200 will represent the tristimulus values X, Y and Z,
`outputs 200 Will represent the tristimulus values X, Y and Z,
`color information to a device that is only able to handle a
`color information to a device that is only able to handle a
`assuming the coefScients have been programmed properly.
`assuming the coef?cients have been programmed properly.
`second and different format of color information.
`second and different format of color information.
`Alternatively, if the RGB input 100 is being converted to at
`Alternatively, if the RGB input 100 is being converted to at
`least one of Srgb and YCbCr, a different set of coefScients
`For example, a common format of color information is
`For example, a common format of color information is
`least one of Srgb and YCbCr, a different set of coef?cients
`will have been loaded; and the outputs 200 will represent
`RGB video. It is therefore desirable to provide methods and
`RGB video. It is therefore desirable to provide methods and
`Will have been loaded, and the outputs 200 Will represent
`apparatus for converting the RGB video into other formats, 35 Srgb; j e ; device independent RGB.
`apparatus for converting the RGB video into other formats,
`Srgb, i.e., device independent RGB.
`35
`such as, for example, Lab video, YCbCr video, with or
`such as, for example, Lab video, YCbCr video, With or
`If the RGB input 100 is being converted to Lab, then the
`If the RGB input 100 is being converted to Lab, then the
`without gamma correction, and/or Srgb video (scanner inde­
`Without gamma correction, and/or Srgb video (scanner inde
`outputs 200 of the multiplier 10 are provided to SRAM
`outputs 200 of the multiplier 10 are provided to SRAM
`pendent RGB) with or without gamma correction. The
`pendent RGB) With or Without gamma correction. The
`look-up tables 20. In such a situation, the tables can contain
`look-up tables 20. In such a situation, the tables can contain
`apparatus and methods of the invention can use look-up
`apparatus and methods of the invention can use look-up
`data necessary for the Lab conversion.
`data necessary for the Lab conversion.
`tables to hold data for a non-linear portion of the Lab 4Q
`tables to hold data for a non-linear portion of the Lab
`If the RGB input 100 is being converted to either YCbCr
`If the RGB input 100 is being converted to either YCbCr
`conversion process and/or to hold data for gamma correction
`conversion process and/or to hold data for gamma correction
`of Srgb with gamma correction, or any other type of
`of Srgb With gamma correction, or any other type of
`curves.
`correction involving non-linear transformation of the video
`correction involving non-linear transformation of the video
`curves.
`The invention therefore provides the advantage of
`data, then the outputs 200 of the multiplier 10 are also
`The invention therefore provides the advantage of
`data, then the outputs 200 of the multiplier 10 are also
`increasing the flexibility of image information communica­
`increasing the ?exibility of image information communica
`provided to the SRAM look-up tables 20. In such a situation,
`provided to the SRAM look-up tables 20. In such a situation,
`tion by enabling devices to handle image information that 45 the tables can contain data necessary for such a non-linear
`tion by enabling devices to handle image information that
`the tables can contain data necessary for such a non-linear
`45
`had not been initially formatted to be compatible with the
`transformation.
`had not been initially formatted to be compatible With the
`transformation.
`devices. The invention thereby increases the amount of
`The SRAM look-up tables 20 can be located external to
`devices. The invention thereby increases the amount of
`The SRAM look-up tables 20 can be located external to
`image information that can be handled by various devices.
`any device implementing the invention. Alternatively, the
`image information that can be handled by various devices.
`any device implementing the invention. Alternatively, the
`SRAM look-up tables 20 can be incorporated into, and
`SRAM look-up tables 20 can be incorporated into, and
`These and other features and advantages of this invention
`These and other features and advantages of this invention
`disposed internally relative to, the device.
`are described in or are apparent from the following detailed 50 disposed internally relative to, the device,
`are described in or are apparent from the folloWing detailed
`The invention can use a bit from a mode control register
`description of various exemplary embodiments of the sys­
`The invention can use a bit from a mode control register
`description of various exemplary embodiments of the sys
`(not shown) to select which sections of the tables are to be
`tems and methods according to this invention.
`(not shoWn) to select Which sections of the tables are to be
`tems and methods according to this invention.
`used. This procedure would allow the tables to be loaded
`used. This procedure Would alloW the tables to be loaded
`BRIEF DESCRIPTION OF THE DRAWINGS
`once, such as at power up, and still allow the data to be
`BRIEF DESCRIPTION OF THE DRAWINGS
`once, such as at poWer up, and still alloW the data to be
`55 changed easily via software, as opposed to PROM based
`changed easily via softWare, as opposed to PROM based
`55
`Various exemplary embodiments of systems and methods
`Various exemplary embodiments of systems and methods
`look-up tables.
`look-up tables.
`according to this invention will be described in detail, with
`according to this invention Will be described in detail, With
`If the RGB input 100 is being converted to either YCbCr
`If the RGB input 100 is being converted to either YCbCr
`reference to the following figure, wherein:
`reference to the folloWing ?gure, Wherein:
`or Srgb without gamma correction, or any other type of
`or Srgb Without gamma correction, or any other type of
`FIG. 1 is a block diagram of a method and apparatus for
`FIG. 1 is a block diagram of a method and apparatus for
`correction involving non-linear transformation of the video
`correction involving non-linear transformation of the video
`transforming RGB video in accordance with an exemplary 60 data; then the outputs 200 of the multiplier 10 are provided
`transforming RGB video in accordance With an exemplary
`data, then the outputs 200 of the multiplier 10 are provided
`embodiment of the invention.
`embodiment of the invention.
`directly to a linear bypass circuit 30. The outputs 210 of the
`directly to a linear bypass circuit 30. The outputs 210 of the
`SRAM look-up tables 20 are also provided to the linear
`SRAM look-up tables 20 are also provided to the linear
`DETAILED DESCRIPTION OF PREFERRED
`DETAILED DESCRIPTION OF PREFERRED
`bypass circuit 30. The linear bypass circuit 30 obviates
`bypass circuit 30. The linear bypass circuit 30 obviates
`EMBODIMENTS
`EMBODIMENTS
`reloading the tables with 1:1 data for no gamma correction
`reloading the tables With 1:1 data for no gamma correction
`FIG. 1 is a block diagram that shows a method and 65 or other non-linear transformation,
`FIG. 1 is a block diagram that shoWs a method and
`or other non-linear transformation.
`65
`apparatus for transforming RGB video in accordance with
`If the RGB input 100 is being converted to Lab, then the
`apparatus for transforming RGB video in accordance With
`If the RGB input 100 is being converted to Lab, then the
`an exemplary embodiment of the invention. As shown in
`outputs of the SRAM look-up tables are provided, via the
`outputs of the SRAM look-up tables are provided, via the
`an exemplary embodiment of the invention. As shoWn in
`
`

`
`3
`3
`linear bypass circuit 30, to a hard coded Lab converter
`linear bypass circuit 30, to a hard coded Lab converter
`circuit 40. The Lab converter circuit 40 can implement the
`circuit 40. The Lab converter circuit 40 can implement the
`following:
`following:
`
`US 6,486,889 B1
`US 6,486,889 B1
`
`£=296 /(50-41;
`
`a=500 \f(X)-f(Y)]+128;
`
`and
`
`6=200 \f(Y)-F(Z)]+128;
`
`4
`4
`As discussed above, a programmable mode register (not
`As discussed above, a programmable mode register (not
`shown) can be provided to determine the color space to
`shoWn) can be provided to determine the color space to
`which the RGB input 100 is to be converted. In other words,
`Which the RGB input 100 is to be converted. In other Words,
`the output circuit 50 outputs at least one of Lab, Srgb and
`the output circuit 50 outputs at least one of Lab, Srgb and
`5 YCbCr based on the setting of the programmable mode
`YCbCr based on the setting of the programmable mode
`register.
`register.
`The exemplary embodiment discussed above increases
`The exemplary embodiment discussed above increases
`the flexibility of image information communication by con­
`the ?exibility of image information communication by con
`verting an RGB input 100 into at least one of Lab, Srgb and
`verting an RGB input 100 into at least one of Lab, Srgb and
`10 YCbCr video. This conversion enables RGB video infor-
`YCbCr video. This conversion enables RGB video infor
`10
`mation to be provided to a device that can only handle one
`mation to be provided to a device that can only handle one
`of Lab, Srgb and/or YCbCr video.
`of Lab, Srgb and/or YCbCr video.
`The exemplary embodiments of the apparatus and meth­
`The exemplary embodiments of the apparatus and meth
`ods are described above relative to converting RGB video to
`ods are described above relative to converting RGB video to
`15 at least one of Lab, Srgb and YCbCr video. However, the
`at least one of Lab, Srgb and YCbCr video. HoWever, the
`15
`invention is not intended to be limited to these examples.
`invention is not intended to be limited to these examples.
`Instead, the invention is intended to cover conversions of
`Instead, the invention is intended to cover conversions of
`video formats other than those discussed above. For
`video formats other than those discussed above. For
`example, the invention can cover conversions of information
`example, the invention can cover conversions of information
`The output 400 of the Lab converter circuit 40 is then 20 not relating to color imaging. In fact, the invention can cover
`not relating to color imaging. In fact, the invention can cover
`The output 400 of the Lab converter circuit 40 is then
`20
`conversions of information not relating to imaging or image
`conversions of information not relating to imaging or image
`provided to an output circuit 50. The output circuit 50
`provided to an output circuit 50. The output circuit 50
`information.
`information.
`provides the Lab video output 1000.
`provides the Lab video output 1000.
`The various devices described above can be implemented
`The various devices described above can be implemented
`If the RGB input 100 is being converted to Srgb, with or
`If the RGB input 100 is being converted to Srgb, With or
`using a programmed general purpose computer. However,
`using a programmed general purpose computer. HoWever,
`without gamma correction or any other type of non-linear
`Without gamma correction or any other type of non-linear
`transformation, then the output 300 of the linear bypass 25 the various devices described above can also be imple-
`the various devices described above can also be imple
`25
`transformation, then the output 300 of the linear bypass
`mented on a special purpose computer, a programmed
`circuit 30 is provided directly to the output circuit 50, which
`mented on a special purpose computer, a programmed
`circuit 30 is provided directly to the output circuit 50, Which
`microprocessor or microcontroller and peripheral integrated
`microprocessor or microcontroller and peripheral integrated
`then provides the Srgb video output 1000. No further
`then provides the Srgb video output 1000. No further
`circuit elements, an ASIC or other integrated circuit, a
`operations are required for the conversion since, as dis­
`circuit elements, an ASIC or other integrated circuit, a
`operations are required for the conversion since, as dis
`digital signal processor, a hardwired electronic or logic
`cussed above, the front end 3x3 multiplier 10 can be
`digital signal processor, a hardWired electronic or logic
`cussed above, the front end 3x3 multiplier 10 can be
`30 circuit such as a discrete element circuit, a programmable
`programmed with coefScients to output Srgb.
`circuit such as a discrete element circuit, a programmable
`programmed With coef?cients to output Srgb.
`30
`logic device such as a PLD, PLA, FPGAor PAL, or the like.
`Thus, if the RGB input 100 is being converted to Srgb
`logic device such as a PLD, PLA, FPGA or PAL, or the like.
`Thus, if the RGB input 100 is being converted to Srgb
`In general, any device, capable of implementing a finite state
`In general, any device, capable of implementing a ?nite state
`without gamma correction, or any other type of correction
`Without gamma correction, or any other type of correction
`machine that is in turn capable of implementing the opera­
`machine that is in turn capable of implementing the opera
`involving non-linear transformation of the video data, then
`involving non-linear transformation of the video data, then
`tions discussed above, can be used to implement the various
`the outputs 200 of the multiplier 10 are provided to the
`tions discussed above, can be used to implement the various
`the outputs 200 of the multiplier 10 are provided to the
`operations described above.
`output circuit 50 via the linear bypass circuit 30 . 35 operations described above.
`35
`output circuit 50 via the linear bypass circuit 30.
`Communication links connecting the various devices can
`Alternatively, if the RGB input 100 is being converted to
`Communication links connecting the various devices can
`Alternatively, if the RGB input 100 is being converted to
`be any known or later developed device or system for
`Srgb with gamma correction, or some other type of correc­
`be any knoWn or later developed device or system for
`Srgb With gamma correction, or some other type of correc
`connecting the devices, including a direct cable connection,
`tion involving non-linear transformation of the video data,
`connecting the devices, including a direct cable connection,
`tion involving non-linear transformation of the video data,
`a connection over a wide area network or a local area
`then the outputs 200 of the multiplier 10 are provided to the
`then the outputs 200 of the multiplier 10 are provided to the
`a connection over a Wide area netWork or a local area
`SRAM look-up tables 20, and the outputs 210 of the SRAM 40 network, a connection over an intranet, a connection over
`SRAM look-up tables 20, and the outputs 210 of the SRAM
`netWork, a connection over an intranet, a connection over
`40
`the Internet, or a connection over any other distributed
`look-up tables 20 are provided to the output circuit 50 via the
`the Internet, or a connection over any other distributed
`look-up tables 20 are provided to the output circuit 50 via the
`processing network or system. In general, the communica­
`processing netWork or system. In general, the communica
`linear bypass circuit 30.
`linear bypass circuit 30.
`tion links can be any known or later developed connection
`If the RGB input 100 is being converted to YCbCr, with
`tion links can be any knoWn or later developed connection
`If the RGB input 100 is being converted to YCbCr, With
`system or structure usable to connect the devices.
`or without gamma correction or any other type of non-linear
`system or structure usable to connect the devices.
`or Without gamma correction or any other type of non-linear
`While the systems and methods of this invention have
`transformation, then the output 300 of the linear bypass 45
`While the systems and methods of this invention have
`45
`transformation, then the output 300 of the linear bypass
`been described in conjunction with the specific embodi­
`circuit 30 is provided to a back end 3x3 multiplier 60. The
`been described in conjunction With the speci?c embodi
`circuit 30 is provided to a back end 3x3 multiplier 60. The
`ments outlined above, it is evident that many alternatives,
`output 500 of the back end 3x3 multiplier 60 is then
`ments outlined above, it is evident that many alternatives,
`output 500 of the back end 3x3 multiplier 60 is then
`modifications and variations will be apparent to those skilled
`provided to an offset circuit 70.
`modi?cations and variations Will be apparent to those skilled
`provided to an offset circuit 70.
`in the art. Accordingly, the exemplary embodiments of the
`Eleven bit back end coefficients are provided to the back
`in the art. Accordingly, the exemplary embodiments of the
`Eleven bit back end coefficients are provided to the back
`end 3x3 multiplier 60, and 9 bit offsets are provided to the 50 systems and methods of this invention, as set forth above,
`systems and methods of this invention, as set forth above,
`50
`end 3x3 multiplier 60, and 9 bit offsets are provided to the
`are intended to be illustrative, not limiting. Various changes
`offset circuit 70. The back end 3x3 multiplier 60 and the
`are intended to be illustrative, not limiting. Various changes
`offset circuit 70. The back end 3x3 multiplier 60 and the
`may be made without departing from the spirit and scope of
`offset circuit 70 can perform the following:
`may be made Without departing from the spirit and scope of
`offset circuit 70 can perform the folloWing:
`the invention.
`the invention.
`What is claimed is:
`What is claimed is:
`1. A method of converting RGB video, comprising:
`1. A method of converting RGB video, comprising:
`inputting the RGB video into a converter, the converter
`inputting the RGB video into a converter, the converter
`having a plurality of modes;
`having a plurality of modes;
`setting the converter to at least one of the plurality modes
`setting the converter to at least one of the plurality modes
`which allows the converter to convert the RGB video to
`Which alloWs the converter to convert the RGB video to
`at least one of Lab, Srgb and YCbCr;
`at least one of Lab, Srgb and YCbCr;
`converting the RGB video with the converter to the at
`converting the RGB video With the converter to the at
`least one of Lab, Srgb and YcbCr, wherein
`least one of Lab, Srgb and YcbCr, Wherein
`the inputting step includes inputting 9 bit RGB video and
`the inputting step includes inputting 9 bit RGB video and
`13 bit front end coefScients into a front end 3x3
`13 bit front end coef?cients into a front end 3x3
`multiplier, and the converting step includes performing
`multiplier, and the converting step includes performing
`a matrix multiply as follows:
`a matrix multiply as folloWs:
`
`wherein: be coefficients (0-8) are the programmable back
`Wherein: beicoefficients (0—8) are the programmable back
`end coefScients, and Y, Cb and Cr are the outputs.
`end coef?cients, and Y, Cb and Cr are the outputs.
`The output 600 of the offset circuit 70 is then provided to 65
`The output 600 of the offset circuit 70 is then provided to
`65
`the output circuit 50. The output circuit 50 provides the
`the output circuit 50. The output circuit 50 provides the
`YCbCr video output 1000.
`YCbCr video output 1000.
`
`where X, Y and Z are the inputs to the SRAM look-up tables
`Where X, Y and Z are the inputs to the SRAM look-up tables
`20, and the data in the tables represents a function f which
`20, and the data in the tables represents a function f Which
`is defined as:
`is de?ned as:
`
`f(t) = tK
`= 7.787t + (16/116)
`= 7.787t + (16/116)
`
`1 g t > 0.008856
`2
`1
`t > 0.008856
`0 § t § 0.008856.
`S
`t 2 0.008856.
`0
`
`y=(be coefficient 0)i?+(be coefficient l)G+(be coefficient 2)B+
`of£set_Y;
`
`C£>=(be coefficient 3)i?+(be coefficient 4)G+(be coefficient
`5)Z?+offset_C£>/
`
`and
`and
`
`Cr=(be coefficient 6)/?+(be coefficient 7)G+(be coefficient 8)B+
`offset_0/
`
`55
`
`60
`
`

`
`5
`5
`X=(fe_coeffi.cient O)i?+(fe_coef£cient l)G+(fe_coef£cient 2)5;
`
`and
`and
`
`US 6,486,889 B1
`US 6,486,889 B1
`
`6
`
`Y=(fe_coeffi.cient 3)i?+(fe_coefficient 4)G+(fe_coefficient 5)5;
`
`and
`
`Cr=(be_coeffi.cient 6)/?+(be_coeffi.cient 7)G+(be_coefficient 8)5+
`offset Cr;
`
`Z=(fe_coefficient 6)R+(fe_coef£cient 7)G+(fe_coefficient 8)5;
`
`L=296flr)-41;
`
`a=5OO|ypO-A50]+128;
`
`6=200[flrwiz)]+128;
`
`f(t) = tM
`= 7.787t + (16/116)
`= 7.787t + (16/116)
`
`1 S t > 0.008856
`1 z t > 0.008856
`0 S t < 0.008856.
`0 2 t < 0.008856.
`
`5 wherein: be_coeiEcients (0-8) are the back end coefScients,
`Wherein: beicoefficients (0—8) are the back end coefficients,
`and Y, Cb and Cr are outputs of the offset circuit.
`and Y, Cb and Cr are outputs of the offset circuit.
`wherein: fe coefficients (0-8) are the front end
`10. The method according to claim 9, wherein the con­
`wherein: feicoef?cients (0—8) are the front end
`10. The method according to claim 9, Wherein the con
`coefficients, RGB are three input video components
`verting step includes providing the outputs of the offset
`coefficients, RGB are three input video components
`verting step includes providing the outputs of the offset
`of the 9 bit RGB video input, and XYZ are three
`circuit to an output circuit, and outputting YCbCr video with
`of the 9 bit RGB video input, and XYZ are three
`circuit to an output circuit, and outputting YCbCr video With
`outputs of the front end 3x3 multiplier.
`outputs of the front end 3x3 multiplier.
`10 gamma correction with the output circuit.
`10
`gamma correction With the output circuit.
`2. The method according to claim 1, wherein the convert­
`2. The method according to claim 1, Wherein the convert
`11. The method according to claim 2, wherein the con­
`11. The method according to claim 2, Wherein the con
`ing step includes performing the matrix multiply so that the
`ing step includes performing the matrix multiply so that the
`verting step includes providing the Srgb output from the
`verting step includes providing the Srgb output from the
`front end 3x3 multiplier outputs Srgb video.
`front end 3x3 multiplier outputs Srgb video.
`front end 3x3 multiplier to at least one SRAM look-up table
`front end 3x3 multiplier to at least one SRAM look-up table
`3. The method according to claim 2, wherein the convert­
`3. The method according to claim 2, Wherein the convert
`provided with data necessary for Lab conversion, and out-
`provided With data necessary for Lab conversion, and out
`ing step includes providing the Srgb output from the front 15 pUtting a resu