Standardized color calibration of electronic imagery

Claim 1

A system for recording a standardized color image of an object, comprising: means for forming an image of the object on a plurality of red (r), green (g) and blue (b) detectors, said detectors producing r, g, and b signals characterizing said image as a plurality of r, g, and b pixels; means for recording said r, g, and b signals; means for generating color calibration data including a spectrum of a light source illuminating the object, said color calibration means further including means for generating CIE X, Y, and Z values of said light source as a function of luminance and said CIE X, Y, and Z value generating means including means for providing a gray-scale representation of said light-source, means for recording responses of said r, g, and b detectors for a plurality of different values in said gray scale; and means for transforming said recorded r, g, and b signals into equivalent CIE X, Y, and Z values for the object as illuminated by the light source using said color calibration data.

Claim 2

A system for recording a standardized color image of an object, comprising: means for forming an image of the object on a plurality of red (r), green (g) and blue (b) detectors, said detectors producing r, g, and b signals characterizing said image as a plurality of r, g, and b pixels; means for recording said r, g, and b signals; means for generating color calibration data including a spectrum of a light source illuminating the object, said color calibration means further including means for generating CIE X, Y, and Z values of said light source as a function of luminance and said CIE X, Y, and Z value generating means including means for providing a gray-scale representation of said light-source, means for recording responses of said r, g, and b detectors for a plurality of different values in said gray scale; and means for transforming said recorded r, g, and b signals into equivalent CIE X, Y, and Z values for the object as illuminated by the light source using said color calibration data.

Claim 6

A system for recording a standardized color image of an object, comprising: means for providing electrical signals representing a colored image of the object; means for resolving an output of a light-source illuminating the object into a spectrum; means for providing a gray-scale representation of said light source; and means for calibrating said electrical signals using said spectrum and said gray scale representation of said light source.

Claim 7

A system for recording a standardized color image of an object, comprising: means for providing electrical signals representing a colored image of the object; means for resolving an output of a light-source illuminating the object into a spectrum; means for providing a gray-scale representation of said light source; and means for calibrating said electrical signals using said spectrum and said gray scale representation of said light source.

Claim 12

A system for recording a standardized color image of an object, comprising: means for forming an image of the object on a plurality of red (r), green (g), and blue (b) detectors, said detectors producing r, g, and b signals characterizing said image as a plurality of r, g, and b pixels; means for recording said r, g, and b signals; means for providing a gray-scale representation of a light-source illuminating the object; means for recording responses of said r, g, and b detectors for a plurality of different values in said gray scale; means for converting said r, g, and b detector responses into CIE X, Y and Z values; means for resolving an output of the light-source illuminating the object into a spectrum; means for recording said light-source spectrum using said r, g, and b detectors to produce r, g and b spectra of said light source; means for comparing said r, g and b spectra of said light-source with CIE X, Y, and Z matching curves and generating from said comparison a transformation matrix for converting said r, g and b signals into said CIE X, Y, and Z values; and means for converting, using said transformation matrix, said recorded r, g, and b signals into equivalent CIE X, Y, and Z values for the object as illuminated by the light source using said transformation matrix.

Claim 13

A system for recording a standardized color image of an object, comprising: means for forming an image of the object on a plurality of red (r), green (g), and blue (b) detectors, said detectors producing r, g, and b signals characterizing said image as a plurality of r, g, and b pixels; means for recording said r, g, and b signals; means for providing a gray-scale representation of a light-source illuminating the object; means for recording responses of said r, g, and b detectors for a plurality of different values in said gray scale; means for converting said r, g, and b detector responses into CIE X, Y and Z values; means for resolving an output of the light-source illuminating the object into a spectrum; means for recording said light-source spectrum using said r, g, and b detectors to produce r, g and b spectra of said light source; means for comparing said r, g and b spectra of said light-source with CIE X, Y, and Z matching curves and generating from said comparison a transformation matrix for converting said r, g and b signals into said CIE X, Y, and Z values; and means for converting, using said transformation matrix, said recorded r, g, and b signals into equivalent CIE X, Y, and Z values for the object as illuminated by the light source using said transformation matrix.

Claim 17

An apparatus for use in color calibration comprising: a holder; a spectral plate mounted in said holder for resolving the output of a light-source into a spectrum; and a gray bar mounted in said holder for resolving the output of said light source into a gray scale.

Claim 18

An apparatus for use in color calibration comprising: a holder; a spectral plate mounted in said holder for resolving the output of a light-source into a spectrum; and a gray bar mounted in said holder for resolving the output of said light source into a gray scale.

Claim 22

A method of prod a calibrated color image of an object, comprising the steps of forming an image of the object on a plurality of red (r), green (g) and blue (b) detectors, said detectors producing r, g, and b signals characterizing said image as a plurality of r, g and b pixels; recording said r, g, and b signals; providing a gray-scale representation of a light-source illuminating the object; recording a responses of said r, g, and b detectors for a plurality of different values in said gray scale; converting said r, g, and b detector responses into CIE X, Y, and Z values; resolving an output of the light-source illuminating the object into a spectrum; recording said light-source spectrum using said r, g, and b detectors to produce r, g, and b spectra of said light source; comparing said r, g, and b spectra of said light-source with CIE X, Y, and Z matching curves and generating from said comparison a transformation matrix for converting said r, q, and b signals into said CIE X, Y, and Z values: and converting said r, g, and b signals into CIE X, Y and Z values for the object as illuminated by the light source.

Claim 23

A method of prod a calibrated color image of an object, comprising the steps of forming an image of the object on a plurality of red (r), green (g) and blue (b) detectors, said detectors producing r, g, and b signals characterizing said image as a plurality of r, g and b pixels; recording said r, g, and b signals; providing a gray-scale representation of a light-source illuminating the object; recording a responses of said r, g, and b detectors for a plurality of different values in said gray scale; converting said r, g, and b detector responses into CIE X, Y, and Z values; resolving an output of the light-source illuminating the object into a spectrum; recording said light-source spectrum using said r, g, and b detectors to produce r, g, and b spectra of said light source; comparing said r, g, and b spectra of said light-source with CIE X, Y, and Z matching curves and generating from said comparison a transformation matrix for converting said r, q, and b signals into said CIE X, Y, and Z values: and converting said r, g, and b signals into CIE X, Y and Z values for the object as illuminated by the light source.

Claim 24

A method of prod a calibrated color image of an/object, comprising the steps of: forming an image of the object on a plurality of red (r), green (g), and blue (b) detectors, said detectors producing r, g, and b signals characterizing said image as a plurality of r, g, and b pixels; recording said r, g, and b signals; providing a gray-scale representation of a light-source illuminating the object; recording responses of said r, g, and b detectors for a plurality of different values in said gray scale; linearizing the responses of said r, g, and b detectors for a plurality of different values in said gray scale; resolving an output of the light-source illuminating the object into a spectrum; recording said light-source spectrum using said r, g, and b detectors to produce r, g and b spectra of said light source; linearizing said r, g, and b spectra; comparing said linear r, g, and b spectra of said light-source with CIE X, Y, and Z matching curves and generating from said comparison a transformation matrix for converting said r, g, and b signals into CIE X, Y, and Z values; converting said r, g, and b signals into equivalent CIE X, Y, and Z values for the object as illuminated by the light source; and converting said linearized r, g, and b detector responses into CIE X, Y, and Z values parameterized by luminance.

Claim 25

A method of prod a calibrated color image of an/object, comprising the steps of: forming an image of the object on a plurality of red (r), green (g), and blue (b) detectors, said detectors producing r, g, and b signals characterizing said image as a plurality of r, g, and b pixels; recording said r, g, and b signals; providing a gray-scale representation of a light-source illuminating the object; recording responses of said r, g, and b detectors for a plurality of different values in said gray scale; linearizing the responses of said r, g, and b detectors for a plurality of different values in said gray scale; resolving an output of the light-source illuminating the object into a spectrum; recording said light-source spectrum using said r, g, and b detectors to produce r, g and b spectra of said light source; linearizing said r, g, and b spectra; comparing said linear r, g, and b spectra of said light-source with CIE X, Y, and Z matching curves and generating from said comparison a transformation matrix for converting said r, g, and b signals into CIE X, Y, and Z values; converting said r, g, and b signals into equivalent CIE X, Y, and Z values for the object as illuminated by the light source; and converting said linearized r, g, and b detector responses into CIE X, Y, and Z values parameterized by luminance.

Claim 26

A method of calibrating a color printer, comprising the steps of: creating a table of driving values for driving a printer mechanism; producing a color strip on a test sheet for each table entry; illuminating each color strip with a light source; imaging reflected light from each color strip sequentially through a spectral plate into a detector to generate color strip spectra; imaging sampled light from the light source through the spectral plate into a detector to form a light source spectrum; dividing said color strip spectra by said light source spectrum to provide normalized color strip spectra; convolving said normalized color strip spectra with a CIE X, Y, and Z matching curves to generate the CIE X, Y, and Z values of said color strips; creating a mathematical map correlating said driving values with said CIE X, Y, and Z values; and creating an inverse of said mathematical map for correlating any CIE X, Y, and Z color values with said driving values.

Claim 27

A method of calibrating a color printer, comprising the steps of: creating a table of driving values for driving a printer mechanism; producing a color strip on a test sheet for each table entry; illuminating each color strip with a light source; imaging reflected light from each color strip sequentially through a spectral plate into a detector to generate color strip spectra; imaging sampled light from the light source through the spectral plate into a detector to form a light source spectrum; dividing said color strip spectra by said light source spectrum to provide normalized color strip spectra; convolving said normalized color strip spectra with a CIE X, Y, and Z matching curves to generate the CIE X, Y, and Z values of said color strips; creating a mathematical map correlating said driving values with said CIE X, Y, and Z values; and creating an inverse of said mathematical map for correlating any CIE X, Y, and Z color values with said driving values.