DETERMINATION OF COLOR CHARACTERISTICS OF OBJECTS USING SPATIALLY MODULATED LIGHT

• US 20150276486A1
• Filed: 02/14/2014
• Published: 10/01/2015
• Est. Priority Date: 02/14/2014
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Inventors: Martini, Joerg, Bern, Marshall W., Johnson, Noble M., Kiesel, Peter, Kletter, Doron, Cheng, Bowen, Recht, Michael I.
• Granted Patent: US 10,451,482 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01J 3/51 using colour filters
• CPC Class Codes: G01N 15/1429 Signal processing
• CPC Class Codes: G01N 15/1433 using image recognition
• CPC Class Codes: G01N 15/1434 Optical arrangements
• CPC Class Codes: G01N 15/1459 the analysis being performed on a sample stream
• CPC Class Codes: G01N 15/147 the analysis being performed on a sample stream
• CPC Class Codes: G01N 2015/1006 for cytology
• CPC Class Codes: G01N 2015/1447 Spatial selection
• CPC Class Codes: G01N 2015/1472 with colour
• CPC Class Codes: G01N 2015/1477 Multiparameters

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.

Claims

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 light emanating from the object, the first portion of light having a first wavelength range, the first detector configured to generate a first electrical signal in response to the sensed 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 electrical signal in response to the second portion of light, wherein the first and second signals include information about color distribution of the object.

2. The system of claim 1, further comprising a first optical filter arranged in a path of the emanating light and between the object and the first detector, the first optical filter configured to substantially transmit the first wavelength range to the first detector and to substantially block wavelengths other than the first wavelength range from reaching the first detector.

3. The system of claim 2, wherein the second portion of light comprises light scattered by the object.

4. The system of claim 2, further comprising a second optical filter arranged in a path of the emanating light and between the object and the second detector, the second optical filter configured to substantially transmit the second wavelength range to the second detector and to substantially block wavelengths other than the second wavelength range from reaching the second detector.

5. The system of claim 1, further comprising an analyzer configured to determine the color distribution based on a difference between the first signal and the second signal.

6. The system of claim 1, wherein the information includes information about at least one of an amount or type of color inhomogeneity of the object.

7. The system of claim 6, wherein the type of color inhomogeneity includes one or more of a symmetric color distribution, an asymmetric color distribution, a separated color distribution, and a granular color distribution.

8. The system of claim 1, further comprising 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 and to determine at least one of the amount or type of color inhomogeneity of the object based on the first and second derivative signals.

9. The system of claim 1, further comprising an analyzer configured to perform a cross-correlation of the first electrical signal and the second electrical signal and to determine at least one of the amount or type of color inhomogeneity of the object based on the cross correlation.

10. A device, 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 modulated according to the mask features;

a first detector positioned to sense a first portion of light emanating from the object, the first portion of light having a first wavelength range, the first detector configured to generate an electrical signal in response to the sensed 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 electrical signal in response to the second portion of light, wherein the first and second signal include information about the color characteristics of the object.

11. The device of claim 10, wherein the characteristics of the object include a color distribution of the object.

12. The device of claim 10, wherein the object includes at least first and second color regions and the first signal includes information about a length along the flow direction of the first color region and the second signal includes information about a length along the flow direction of the second color region.

13. The device of claim 10, wherein the object includes at least first and second color regions and the first signal includes information about a width or thickness of the first color region along a direction perpendicular to the flow direction and the second signal includes information about a width or thickness of the second color region along the direction perpendicular to the flow direction.

14. A method, comprising:

sensing light emanating from an object moving with respect to a spatial filter, the emanating light modulated according to mask features of the spatial filter;

generating a first electrical signal in response to sensing a first portion of the emanating light having a first wavelength range; and

generating a second electrical signal in response to sensing a second portion of the emanating light having a second wavelength range, the first and second electrical signals including information about color characteristics of the object.

15. The method of claim 14, further comprising developing a difference signal comprising a difference between the first electrical signal and the second electrical signal.

16. The method of claim 14, further comprising differentiating an amplitude of the first signal and the second signal with respect to time.

17. The method of claim 16, further comprising analyzing color inhomogeneity of the object based on the differentiated signals.

18. The method of claim 16, further comprising:

determining time locations of the signal peaks of the differentiated first and second signals; and

analyzing color characteristics based on the signal peaks.

19. The method of claim 17, wherein the color characteristics includes one or more of a symmetric color distribution, an asymmetric color distribution, a separated color distribution, and a granular color distribution.

20. A device, comprising:

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 emanating from at least one object 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 object and to generate an electrical output signal in response to the sensed light, wherein the electrical output signal includes information about the color distribution of the object.

21. The device of claim 20, wherein the electrical output signal includes information about one or more of a length along the flow direction and width or thickness along a direction perpendicular to the flow direction for each of at least two color regions of the object, the first color region emanating light transmitted by the first mask features and the second color region emanating light transmitted by the second mask features.