Determination of color characteristics of objects using spatially modulated light
First Claim
1. A system, comprising:
- a spatial filter having a plurality of mask features and extending along a flow direction, light emanating from at least one object moving along the flow direction, an intensity of the emanating light being time modulated according to the mask features;
a first detector positioned to sense a first portion of the emanating light, the first portion of light having a first wavelength range, the first detector configured to generate a first time varying electrical signal in response to the first portion of light;
a second detector positioned to sense a second portion of the emanating light, the second portion of light having a second wavelength range different from the first wavelength range, the second detector configured to generate a second time varying electrical signal in response to the second portion of light; and
an analyzer configured to;
calculate a time-varying difference signal comprising a difference between the first electrical signal and the second electrical signal;
identify a frequency component of the time-varying difference signal;
compare the frequency component of the time varying difference signal to a frequency of the mask features; and
determine homogeneous or inhomogeneous color distribution of the object based on the comparison.
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Accused Products
Abstract
A system is configured to determine a color distribution of an object moving along a flow direction relative to a spatial filter. The light emanating from the object is time modulated according to the mask features of the spatial filter. First and second detectors are arranged to sense the modulated light. The first detector senses light having a first wavelength spectrum and generates a first electrical output signal in response to the sensed light. The second detector light senses light having a second wavelength spectrum and generates a second electrical output signal in response to the sensed light. Signals from the first and second detectors include information about color distribution of the object.
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Citations
19 Claims
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1. A system, comprising:
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a spatial filter having a plurality of mask features and extending along a flow direction, light emanating from at least one object moving along the flow direction, an intensity of the emanating light being time modulated according to the mask features; a first detector positioned to sense a first portion of the emanating light, the first portion of light having a first wavelength range, the first detector configured to generate a first time varying electrical signal in response to the first portion of light; a second detector positioned to sense a second portion of the emanating light, the second portion of light having a second wavelength range different from the first wavelength range, the second detector configured to generate a second time varying electrical signal in response to the second portion of light; and an analyzer configured to; calculate a time-varying difference signal comprising a difference between the first electrical signal and the second electrical signal; identify a frequency component of the time-varying difference signal; compare the frequency component of the time varying difference signal to a frequency of the mask features; and determine homogeneous or inhomogeneous color distribution of the object based on the comparison. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system, comprising:
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a spatial filter having a plurality of mask features and extending along a flow direction, light emanating from at least one object moving along the flow direction, an intensity of the emanating light being time modulated according to the mask features; a first detector positioned to sense a first portion of the emanating light, the first portion of light having a first wavelength range, the first detector configured to generate a first time varying electrical signal in response to the first portion of light; a second detector positioned to sense a second portion of the emanating light, the second portion of light having a second wavelength range different from the first wavelength range, the second detector configured to generate a second time varying electrical signal in response to the second portion of light; and an analyzer configured to; develop a first derivative signal comprising a derivative of an amplitude with respect to time of the first electrical signal and a second derivative signal comprising a derivative of an amplitude with respect to time of the second electrical signal; determine at least one peak time of the first derivative signal and at least one peak time of the second derivative signal; and calculate a time difference between the peak time of the first derivative signal and the peak time of the second derivative signal; and determine symmetrical color distribution or asymmetrical color distribution of the object based on the time difference. - View Dependent Claims (9, 10, 11)
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12. A system, comprising:
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a spatial filter having a plurality of mask features and extending along a flow direction, light emanating from at least one object moving along the flow direction, an intensity of the emanating light being time modulated according to the mask features; a first detector positioned to sense a first portion of the emanating light, the first portion of light having a first wavelength range, the first detector configured to generate a first time varying electrical signal in response to the first portion of light; a second detector positioned to sense a second portion of the emanating light, the second portion of light having a second wavelength range different from the first wavelength range, the second detector configured to generate a second time varying electrical signal in response to the second portion of light; and an analyzer configured to; calculate a time-varying difference signal comprising a difference between the first electrical signal and the second electrical signal; perform a cross-correlation of the difference signal and a predicted signal of a homogeneously colored object; and determine an amount of color inhomogeneity of the object based on the cross-correlation. - View Dependent Claims (13, 14)
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15. A device, comprising:
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a spatial filter having a plurality of mask features and extending along a flow direction, the mask features including first features having a first optical transmission characteristic and second features having a second optical transmission characteristic, light in a first wavelength range emanating from a first color region moving along the flow direction and light in a second wavelength range emanating from a second color region moving along the flow direction, an intensity of the emanating light being modulated according to the first mask features and the second mask features; a detector positioned to sense the light emanating from the first and second color regions and to generate a first time-varying electrical output signal in response to the sensed light emanating from the first color region and to generate a second time-varying electrical output signal in response to light emanating from the second color region; and an analyzer configured to; develop a first derivative signal comprising a derivative with respect to time of an amplitude of the first time-varying signal and develop a second derivative signal comprising a derivative with respect to time of an amplitude of the second time-varying signal; identify at least one peak of the first derivative signal and at least one peak of the second derivative signal; calculate a time difference between a time of the peak of the first derivative signal and a time of the peak of the second derivative signal; and determine a spatial separation of the first and second color regions based on the time difference. - View Dependent Claims (16, 17)
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18. A system, comprising:
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a spatial filter having a plurality of mask features and extending along a flow direction, light emanating from at least one object moving along the flow direction, an intensity of the emanating light being time modulated according to the mask features; a first detector positioned to sense a first portion of the emanating light, the first portion of light having a first wavelength range, the first detector configured to generate a first time varying electrical signal in response to the first portion of light; a second detector positioned to sense a second portion of the emanating light, the second portion of light having a second wavelength range different from the first wavelength range, the second detector configured to generate a second time varying electrical signal in response to the second portion of light; and an analyzer configured to; develop a first derivative signal comprising a derivative of an amplitude of the first electrical signal with respect to time and a second derivative signal comprising a derivative of an amplitude of the second electrical signal with respect to time; count a number of local peaks of the first derivative signal that overlap a peak of the second derivative signal; and determine that multiple color regions of the first wavelength range occur within a color region of the second wavelength range if the number of local peaks is greater than one. - View Dependent Claims (19)
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Specification