Dental shade mapping

A method for generating a color mapping for a dental object, executed at least in part by a control logic processor, comprising:

• generating a transformation matrix from a set of spectral reflectance data for a statistically valid sampling of teeth;
• directing illumination toward the dental object over at least a first, a second, and a third wavelength band, one wavelength band at a time;
• obtaining, for each of a plurality of pixels in a first imaging array, a first image data value corresponding to each of the at least first, second, and third wavelength bands;
• applying the transformation matrix to form the color mapping by generating a set of visual color values for each of the plurality of pixels according to the obtained first image data values and according to second image data values obtained from a reference object at the at least first, second, and third wavelength bands;
• and
• storing the color mapping in a computer-accessible electronic memory, wherein generating the transformation matrix comprises:
• generating a plurality of mixture coefficients by applying principal component analysis to the set of spectral reflectance data for the statistically valid sampling of teeth;
• obtaining a set of image sample measurements for elements in the statistically valid sampling of teeth by directing illumination toward each tooth over the at least first, second, and third wavelength band, one wavelength band at a time, and obtaining, from each tooth, at each of a plurality of pixels in a second imaging array, a third image data value corresponding to each of the at least first, second, and third wavelength bands, wherein the set of image sample measurements are obtained at the same locations on said teeth as the set of spectral reflectance data;
• and
• forming the transformation matrix using a least squares fit between the plurality of mixture coefficients and the set of image sample measurements.

A method for generating a color mapping for a dental object, executed at least in part by a control logic processor, comprising:

• generating a transformation matrix from a set of spectral reflectance data for a statistically valid sampling of teeth;
• directing illumination toward the dental object over at least a first, a second, and a third wavelength band, one wavelength band at a time;
• obtaining, for each of a plurality of pixels in a first imaging array, a first image data value corresponding to each of the at least first second and third wavelength bands;
• applying the transformation matrix to form the color mapping by generating a set of visual color values for each of the plurality of pixels according to the obtained first image data values and according to second image data values obtained from a reference object at the at least first, second, and third wavelength bands;
• and
• storing the color mapping in a computer-accessible electronic memory, wherein generating the transformation matrix comprises:
• generating a set of tristimulus values from the set of spectral reflectance data for the statistically valid sampling of teeth;
• obtaining a set of image sample measurements for elements in the statistically valid sampling of teeth by directing illumination toward each tooth over the at least first, second, and third wavelength band, one wavelength band at a time, and obtaining, from each tooth, at each of a plurality of pixels in a second imaging array, a third image data value corresponding to each of the at least first, second, and third wavelength bands, wherein the set of image sample measurements are obtained at the same locations on said teeth as the set of spectral reflectance data;
• generating a plurality of mixture coefficients by applying principal component analysis to the set set of image sample measurements;
• and
• forming the transformation matrix using a least squares fit between the plurality of mixture coefficients and the set of tristimulus values.

A method for generating a color mapping for a dental object, executed at least in part by a control logic processor, comprising:

• generating a transformation matrix from a set of spectral reflectance data for a statistically valid sampling of teeth;
• directing illumination toward the dental object over at least a first, a second, and a third wavelength band, one wavelength band at a time;
• obtaining, for each of a plurality of pixels in a first imaging array, a first image data value corresponding to each of the at least first, second, and third wavelength bands;
• applying the transformation matrix to form the color mapping by generating a set of visual color values for each of the plurality of pixels according to the obtained first image data values and according to second image data values obtained from a reference object at the at least first, second, and third wavelength bands;
• and
• storing the color mapping in a computer-accessible electronic memory,
• wherein generating the transformation matrix comprises:
• generating a set of tristimulus values from the set of spectral reflectance data for the statistically valid sampling of teeth;
• obtaining a set of image sample measurements for elements in the statistically valid sampling of teeth by directing illumination toward each tooth over the at least first, second, and third wavelength band, one wavelength band at a time, and obtaining, from each tooth, at each of a plurality of pixels in a second imaging array, a third image data value corresponding to each of the at least first, second, and third wavelength bands, wherein the set of image sample measurements are obtained at the same locations on said teeth as the set of spectral reflectance data;
• and
• forming the transformation matrix using a least squares fit between the set of tristimulus values and the set of image sample measurements.

A method for generating a color mapping for a dental object, executed at least in part by a control logic processor, comprising:

• generating a transformation matrix from a set of spectral reflectance data for a statistically valid sampling of teeth;
• directing illumination toward the dental object over at least a first, a second, and a third wavelength band, one wavelength band at a time;
• obtaining, for each of a plurality of pixels in a first imaging array, a first image data value corresponding to each of the at least first, second, and third wavelength bands;
• applying the transformation matrix to form the color mapping by generating a set of visual color values for each of the plurality of pixels according to the obtained first image data values and according to second image data values obtained from a reference object at the at least first, second, and third wavelength bands;
• and
• storing the color mapping in a computer-accessible electronic memory, wherein generating the transformation matrix comprises:
• generating a set of visual color values from the set of spectral reflectance data for the statistically valid sampling of teeth;
• obtaining a set of image sample measurements for elements in the statistically valid sampling of teeth by directing illumination toward each tooth over the at least first, second, and third wavelength band, one wavelength band at a time, and obtaining, from each tooth, at each of a plurality of pixels in a second imaging array, a third image data value corresponding to each of the at least first, second, and third wavelength bands, wherein the set of image sample measurements are obtained at the same locations on said teeth as the set of spectral reflectance data;
• generating an expanded set of image sample measurements by including transformed values of each of the image sample measurements;
• and
• forming the transformation matrix using a least squares fit between the generated set of visual color values and the expanded set of image sample measurements.

A method for generating a color mapping for a dental object, executed at least in part by a control logic processor, the method comprising:

• generating a transformation matrix from a first set of spectral reflectance data and a set of image sample measurements for a statistically valid sampling of teeth, the image sample measurements being obtained by directing illumination toward each tooth over at least a first, a second, and a third wavelength band, one wavelength band at a time, and obtaining, from each tooth, at each of a plurality of pixels in a first imaging array, a first image data value corresponding to each of the at least first, second, and third wavelength bands wherein the set of image sample measurements are obtained at the same locations on said teeth as the set of spectral reflectance data;
• directing illumination toward the dental object over the at least first, second, and third wavelength band, one wavelength band at a time;
• obtaining, for each of a plurality of pixels in a second imaging array, a second image data value corresponding to each of the at least first, second, and third wavelength bands;
• generating a second set of spectral reflectance data for each of the plurality of pixels by processing the second image data value for each of the at least first, second, and third wavelength bands according to the generated transformation matrix and according to third image data values obtained from a reference object at the at least first, second, and third wavelength bands;
• forming the color mapping by reconstructing a set of visual color values of the dental object according to the generated second set of spectral reflectance data values for each of the plurality of pixels and according to spectral distribution values of a viewing illuminant;
• and
• transmitting the color mapping or storing the color mapping in an electronic memory.