Vehicle imaging system and method for distinguishing reflective objects from lights of another vehicle

1. An imaging system for a vehicle, comprising:

an imager configured to image a scene external and forward of the vehicle and to generate image data corresponding to acquired images; and

a processor configured to receive and analyze the image data to detect the presence of a light source and to identify whether such light source is a light of another vehicle;

wherein:

when a light source is detected, said processor is configured to generate a signal that is used to control exterior lights of the vehicle to temporarily modulate at least a portion of an illumination pattern projected from the exterior lights to have a particular modulation pattern at least in the direction of the detected light source,

after generating the signal, said processor is configured to analyze the image data subsequently received to detect whether the light source has a modulation pattern corresponding to the modulation pattern of the exterior lights,

when the light source does have such a modulation pattern, said processor is configured to determine that the light source is a reflective object and not a light of another vehicle, and

when the light source does not have such a modulation pattern, said processor is configured to determine that the light source may be a light of another vehicle.

2. The imaging system of claim 1 , wherein the modulation pattern used to modulate the exterior lights is a unique modulation pattern to the vehicle.

3. The imaging system of claim 1 , wherein the modulation pattern is one of a random and a pseudorandom pattern.

4. The imaging system of claim 3 , wherein the pseudorandom modulation pattern is selected using a seed value corresponding to one of: select digits from a VIN of the vehicle, a time value corresponding to the time since a beginning of a current vehicle ignition cycle, and a number of frames captured since a beginning of a current vehicle ignition cycle.

5. The imaging system of claim 1 , wherein said processor analyzes the image data subsequently received to detect whether the light source has a modulation pattern corresponding to the modulation pattern of the exterior lights within a predetermined time window after a control signal was generated to modulate the exterior lights.

6. The imaging system of claim 1 , wherein the exterior lights are modulated at a frequency that is a multiple of at least one of 120 Hz, 100 Hz, and 50 Hz, and wherein said processor treats any light sources having a modulation pattern that is a multiple of at least one of 120 Hz, 100 Hz, and 50 Hz as nonvehicle light sources.

7. The imaging system of claim 1 , wherein said processor is configured to generate additional signals that are used to control the exterior lights in response to determinations that a light of another vehicle is present or a determination that another vehicle is no longer present.

8. A method for distinguishing between a light of another vehicle and a reflective object, comprising:

providing an imager for use in a vehicle;

imaging a scene external and forward of the vehicle and generating image data corresponding to the acquired images;

receiving and analyzing the image data in a processor to detect the presence of a light source and to identify whether such light source is a light of another vehicle;

when a light source is detected, generating a control signal to control exterior lights of the vehicle to temporarily modulate at least a portion of an illumination pattern projected from the exterior lights to have a particular modulation pattern at least in the direction of the detected light source;

after generating the control signal, analyzing the image data subsequently received to detect whether the light source has a modulation pattern corresponding to the modulation pattern of the exterior lights;

when the light source does have such a modulation pattern, determining that the light source is a reflective object and not a light of another vehicle; and

when the light source does not have such a modulation pattern, determining that the light source may be a light of another vehicle.

9. The method of claim 8 , wherein the modulation pattern used to modulate the exterior lights is a unique modulation pattern to the vehicle.

10. The method of claim 8 , wherein the modulation pattern is one of a random and a pseudorandom pattern.

11. The method of claim 10 , wherein the pseudorandom modulation pattern is selected using a seed value corresponding to one of: select digits from a VIN of the vehicle, a time value corresponding to the time since a beginning of a current vehicle ignition cycle, and a number of frames captured since a beginning of a current vehicle ignition cycle.

12. The method of claim 8 , wherein the step of analyzing the image data subsequently received to detect whether the light source has a modulation pattern corresponding to the modulation pattern of the exterior lights is performed within a predetermined time window after the control signal was generated to modulate the exterior lights.

13. The method of claim 8 , wherein the exterior lights are modulated at a frequency that is a multiple of at least one of 120 Hz, 100 Hz, 60 Hz, and 50 Hz, and wherein said processor treats any light sources having a modulation pattern that is a multiple of at least one of 120 Hz, 100 Hz, 60 Hz, and 50 Hz as nonvehicle light sources.

14. A non-transitory computer readable medium having stored thereon software instructions that, when executed by a processor within a vehicle, cause the processor to distinguish between a light of another vehicle and a reflective object, by executing the steps comprising:

controlling an imager to image a scene external and forward of the vehicle and generate image data corresponding to the acquired images;

receiving and analyzing the image data in a processor to detect the presence of a light source and to identify whether such light source is a light of another vehicle;

when a light source is detected, generating a control signal to control exterior lights of the vehicle to temporarily modulate at least a portion of an illumination pattern projected from the exterior lights to have a particular modulation pattern at least in the direction of the detected light source;

after generating the control signal, analyzing the image data subsequently received to detect whether the light source has a modulation pattern corresponding to the modulation pattern of the exterior lights;

when the light source does have such a modulation pattern, determining that the light source is a reflective object and not a light of another vehicle; and

when the light source does not have such a modulation pattern, determining that the light source may be a light of another vehicle.

15. The non-transitory computer readable medium of claim 14 , wherein the modulation pattern used to modulate the exterior lights is a unique modulation pattern to the vehicle.

16. The non-transitory computer readable medium of claim 14 , wherein the modulation pattern is one of a random and a pseudorandom pattern.

17. The non-transitory computer readable medium of claim 16 , wherein the pseudorandom modulation pattern is selected using a seed value corresponding to one of: select digits from a VIN of the vehicle, a time value corresponding to the time since a beginning of a current vehicle ignition cycle, and a number of frames captured since a beginning of a current vehicle ignition cycle.

18. The non-transitory computer readable medium of claim 14 , wherein the step of analyzing the image data subsequently received to detect whether the light source has a modulation pattern corresponding to the modulation pattern of the exterior lights is performed within a predetermined time window after the control signal was generated to modulate the exterior lights.

19. The non-transitory computer readable medium of claim 14 , wherein the exterior lights are modulated at a frequency that is a multiple of at least one of 120 Hz, 100 Hz, 60 Hz, and 50 Hz, and wherein said processor treats any light sources having a modulation pattern that is a multiple of at least one of 120 Hz, 100 Hz, 60 Hz, and 50 Hz as nonvehicle light sources.

20. The non-transitory computer readable medium of claim 14 , wherein the software instructions further cause the processor to generate an exterior light control signal that is used to control the exterior lights in response to determinations that a light of another vehicle is present or a determination that another vehicle is no longer present.