Detection and Classification of Light Sources Using a Diffraction Grating

• US 20090182690A1
• Filed: 01/13/2009
• Published: 07/16/2009
• Est. Priority Date: 01/15/2008
• Status: Active Grant

• Current Assignee: MobilEye Vision Technologies Ltd. (Intel Corporation)
• Original Assignee: MobilEye Vision Technologies Ltd. (Intel Corporation)
• Inventors: Stein, Gideon
• Granted Patent: US 9,176,006 B2
• Time in Patent Office: Days
• US Class Current: 706/12
• CPC Class Codes: G01J 1/04 Optical or mechanical part supplementary adjustable parts
• CPC Class Codes: G01J 1/0407 Optical elements not provided otherwise, e.g. manifolds, windows, holograms, gratings
• CPC Class Codes: G01J 1/4228 arrangements with two or more detectors, e.g. for sensitivity compensation
• CPC Class Codes: G01J 2001/4247 for testing lamps or other light sources
• CPC Class Codes: G01J 2003/2836 Programming unit, i.e. source and date processing
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0205 Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
• CPC Class Codes: G01J 3/0208 using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
• CPC Class Codes: G01J 3/18 using diffraction elements, e.g. grating gratings per se G02B
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01J 3/2803 using photoelectric array detector
• CPC Class Codes: G01J 3/2823 Imaging spectrometer
• CPC Class Codes: G01J 3/46 Measurement of colour; Colour measuring devices, e.g. colorimeters measuring colour temperature G01J5/60
• CPC Class Codes: G02B 5/04 Prisms
• CPC Class Codes: G06N 20/00 Machine learning
• CPC Class Codes: G06N 20/10 using kernel methods, e.g. support vector machines [SVM]

Abstract

A system mounted in a vehicle for classifying light sources. The system includes a lens and a spatial image sensor. The lens is adapted to provide an image of a light source on the spatial image sensor. A diffraction grating is disposed between the lens and the light source. The diffraction grating is adapted for providing a spectrum. A processor is configured for classifying the light source as belonging to a class selected from a plurality of classes of light sources expected to be found in the vicinity of the vehicle, wherein the spectrum is used for the classifying of the light source. Both the image and the spectrum may be used for classifying the light source or the spectrum is used for classifying the light source and the image is used for another driver assistance application.

Claims

1. A system mounted in a vehicle, the system for classifying a light source, the system comprising:

a spatial image sensor;

a lens that is adapted to provide an image of a light source on said spatial image sensor;

a diffraction grating disposed between said lens and said light source, said diffraction grating adapted to provide a spectrum; and

a processor configured to classify said light source as belonging to a class selected from a plurality of classes of light sources expected to be found in a vicinity of the vehicle, said processor using said spectrum to classify said light source.

2. The system according to claim 1, wherein said spectrum is sensed by said spatial image sensor.

3. The system according to claim 1, wherein the light source is selected from the group consisting of streetlights, headlights, taillights and traffic signs.

4. The system according to claim 1, further comprising a hood enclosure that is configured to limit a field of view so that an image provided by said lens does not superimpose said spectrum.

5. The system according to claim 1, wherein the processor uses both said image and said spectrum to classify said light source.

6. The system according to claim 1, wherein said image is not used in the classifying, wherein said image is usable for a driver assistance application.

7. The system according to claim 1, wherein said diffraction grating is a holographic diffraction grating.

8. The system according to claim 1, wherein said diffraction grating is a blazed diffraction grating.

9. The system according to claim 8, wherein said diffraction grating is blazed at a wavelength selected based on a known spectrum of a known light source.

10. The system according to claim 1, wherein said spatial image sensor has at least one programmable photosensitive gain region.

11. The system according to claim 1, further comprising a second spatial image sensor that detects said spectrum.

12. The system according to claim 1, further comprising a second spatial image sensor, wherein said spatial image sensor and said second spatial image sensor have different electronic gains.

13. The system according to claim 1, wherein said lens and said diffraction grating are are a single optical element.

14. A method of classifying a light source using a system including a camera equipped with a lens and a spatial image sensor, the lens providing an image of the light source on the spatial image sensor, the method comprising:

training at least one classifier based on a plurality of known spectra of light sources expected to be found in a vicinity of the system thereby producing at least one trained classifier;

detecting the image of the light source;

providing a spectrum of the light source;

locating said spectrum on the spatial image sensor; and

classifying the light source based on said spectrum as belonging to a class selected from a plurality of classes of the light sources, by applying said at least one trained classifier.

15. The method, according to claim 14, wherein said classifying is performed by applying rules based on at least one known spectrum of the light sources expected to be found in the vicinity of the system.

16. The method according to claim 14, wherein said at least one classifier includes a least one binary classifier.

17. The method according to claim 14, wherein said at least one classifier is based on support vector machines.

18. The method, according to claim 14, wherein said classifying is based on both said spectrum and said image.

19. The method, according to claim 14, wherein said spectrum is selectably produced by either a diffraction grating or a prism.

20. A system for classifying a light source, the system comprising:

a spatial image sensor;

a lens that provides an image of a light source on said spatial image sensor;

a diffraction grating or prism disposed between said lens and said light source, said diffraction grating or prism adapted to provide a spectrum; and

a processor configured to classify said light source as belonging to a class selected from a plurality of classes of light sources,

wherein said spectrum is used by said processor to classify said light source.

21. A system for classifying a light source, the system comprising:

a diffraction grating that diffracts light from a light source;

a pair of spatial image sensors, a first of the pair being disposed to receive a direct transmission of focused, diffracted light corresponding to a zeroth diffraction order, a second of the pair being disposed to receive an indirect transmission of focused, diffracted light corresponding to a first diffraction peak;

a lens that focuses light diffracted by the diffraction grating into images on respective ones of the pair of spatial image sensors, a first image corresponding to the zeroth diffraction order being focused on the first spatial image sensor, a second image corresponding to the first diffraction peak being focused on the second spatial image sensor; and

a processor that uses the images sensed by the spatial image sensors to classify the light source into one of a specified set of light source classes.