Color signature sensor

Claim 1

A color signature sensor for recognizing color of an object with said sensor having a diffraction grating for spectrally dispersing light received from an object being observed onto a detector array, the detector array having a plurality of photodetectors each photodetector providing an output signal according to the time and space integrated spectrally dispersed light from said object, an analog-to-digital converter to digitize the signals from the detector array with one digitized signal per photodetector to form a digitized set of signals for evaluation in a microprocessor and memory, including in said sensor, microprocessor and memory: means for illuminating an object B being observed; diffraction grating means for spectrally dispersing light received from said object B; means for converting said dispersed light into electrical signals; means for digitizing the signals; means for receiving and storing the sampled and digitized sets of signals from a reference object A and from the object B being observed, described collectively as ##EQU13## where m is the number of photodetectors in the array, n is the bit precision of the digitization process, ##EQU14## is an ordered sequence of weighted numbers (a 0 , a 1 , a 2 . . . a m-1 ) representing the unnormalized spectral constitution of color object A, ##EQU15## is an ordered sequence of weighted numbers (b 0 , b 1 , b 2 . . . b m-1 ) representing the unnormalized spectral constitution of the colored object B; means for determining means values η a and η b according to relations ##EQU16## where Σ is the summation of the m weighted values; means for determining cross-correlation ψ between I mn (A) and I mn (B) according to a relation ##EQU17## means for determining means value difference φ between I mn (A) and I mn (B) according to a relation φ(A,B)=η a -η b ; and, means providing a discrimination threshold for cross-correlation σ cc and providing a discrimination threshold for mean-value difference σ mvd , whereby two colors can be discriminated provided |ψ(A,A')-ψ(A,B)|>σ.sub.cc >0 |Φ(A,A')-Φ(A,B)|>σ.sub.mvd >0 while if |ψ(A,A')-ψ(A,B)|≦σ.sub.cc and |Φ(A,A')-Φ(A,B)|≦σ.sub.mvd, the sample colors of A and B are said to match.

Claim 3

A method for comparing color of an object B as compared with color of a reference A comprising the steps of: providing illumination to an object B being observed; providing optical path means for observing a reference object A or an object B and directing light therefrom to a spectral dispersive element; providing a spectral dispersive element for spectrally dispersing light received on the optical path providing a detector array for receiving the spectrally dispersed light and converting it to a set of analog electrical signals; receiving and converting a set of analog signals representative of color of the reference A to a set of digital signals; storing the digital signals, representative of the reference color A, described collectively as ##EQU18## m is a number of photodetectors, n is bit precision of the digitization process, ##EQU19## is an ordered sequence of weighted numbers (a 0 , a 1 , a 2 . . . a m-1 ) representing unnormalized spectral constitution of colored object A; receiving and converting similarly a set of digital signals representative of object color B, described collectively as ##EQU20## ##EQU21## is an ordered sequence of weighted numbers (b 0 , b 1 , b 2 . . . B m-1 ) representing the unnormalized spectral constitution of colored object B; determining the mean-values η a and η b according to two relations ##EQU22## where Σ is the summation of m weighted values; determining cross-correlation ψ between I mn (A) and I mn (B) according to a relation ##EQU23## determining mean-value difference φ between I mn (A) and I mn (B) according to a relation φ(A,B)=η a -η b ; providing a discrimination threshold for cross-correlation σ cc and providing a discrimination threshold for mean-value difference σ mvd ; and, comparing object A and object B values whereby two colors can be discriminated provided |ψ(A,A')-ψ(A,B)|>σ.sub.cc >0 or |Φ(A,A')-Φ(A,B)|>σ.sub.mvd >0 while if |ψ(A,A')-ψ(A,B)|≦σ.sub.cc and |Φ(A,A')-Φ(A,B)|≦σ.sub.mvd, the sample colors of A and B are said to match.

Claim 4

A method for comparing color of an object B as compared with color of a reference A comprising the steps of: providing illumination to an object B being observed; providing optical path means for observing a reference object A or an object B and directing light therefrom to a spectral dispersive element; providing a spectral dispersive element for spectrally dispersing light received on the optical path providing a detector array for receiving the spectrally dispersed light and converting it to a set of analog electrical signals; receiving and converting a set of analog signals representative of color of the reference A to a set of digital signals; storing the digital signals, representative of the reference color A, described collectively as ##EQU18## m is a number of photodetectors, n is bit precision of the digitization process, ##EQU19## is an ordered sequence of weighted numbers (a 0 , a 1 , a 2 . . . a m-1 ) representing unnormalized spectral constitution of colored object A; receiving and converting similarly a set of digital signals representative of object color B, described collectively as ##EQU20## ##EQU21## is an ordered sequence of weighted numbers (b 0 , b 1 , b 2 . . . B m-1 ) representing the unnormalized spectral constitution of colored object B; determining the mean-values η a and η b according to two relations ##EQU22## where Σ is the summation of m weighted values; determining cross-correlation ψ between I mn (A) and I mn (B) according to a relation ##EQU23## determining mean-value difference φ between I mn (A) and I mn (B) according to a relation φ(A,B)=η a -η b ; providing a discrimination threshold for cross-correlation σ cc and providing a discrimination threshold for mean-value difference σ mvd ; and, comparing object A and object B values whereby two colors can be discriminated provided |ψ(A,A')-ψ(A,B)|>σ.sub.cc >0 or |Φ(A,A')-Φ(A,B)|>σ.sub.mvd >0 while if |ψ(A,A')-ψ(A,B)|≦σ.sub.cc and |Φ(A,A')-Φ(A,B)|≦σ.sub.mvd, the sample colors of A and B are said to match.

Claim 7

A method for comparing color of an object B as compared with color of a reference A comprising the steps of: providing optical path means for observing a colored reference object A and directing light therefrom to a spectral dispersive element; providing a spectral dispersive element for spectrally dispersing light received on the optical path; providing a detector array for receiving the spectrally dispersed light and converting it to a set of analog electrical signals; receiving and converting a set of analog signals representative of color of the reference A to a set of digital signals; storing the digital signals, representative of the reference color A, described collectively as an ordered sequence of weighted numbers representing the unnormalized spectral constitution of the colored object A; receiving and converting similarly a set of signals representative of object color B, described collectively as an ordered sequence of weighted numbers representing the unnormalized spectral constitution of the colored object B; determining mean-values of said digital sets of signals; determining cross-correlation between said sets of signals; determining mean-value difference between the first and second set of signals; providing a discrimination threshold for cross-correlation and providing a discrimination threshold for mean-value difference; and, comparing object A and object B correlations and mean-value difference values whereby two colors can be discriminated.

Claim 8

A method for comparing color of an object B as compared with color of a reference A comprising the steps of: providing optical path means for observing a colored reference object A and directing light therefrom to a spectral dispersive element; providing a spectral dispersive element for spectrally dispersing light received on the optical path; providing a detector array for receiving the spectrally dispersed light and converting it to a set of analog electrical signals; receiving and converting a set of analog signals representative of color of the reference A to a set of digital signals; storing the digital signals, representative of the reference color A, described collectively as an ordered sequence of weighted numbers representing the unnormalized spectral constitution of the colored object A; receiving and converting similarly a set of signals representative of object color B, described collectively as an ordered sequence of weighted numbers representing the unnormalized spectral constitution of the colored object B; determining mean-values of said digital sets of signals; determining cross-correlation between said sets of signals; determining mean-value difference between the first and second set of signals; providing a discrimination threshold for cross-correlation and providing a discrimination threshold for mean-value difference; and, comparing object A and object B correlations and mean-value difference values whereby two colors can be discriminated.