Vehicle camera image quality improvement in poor visibility conditions by contrast amplification

• US 9,681,062 B2
• Filed: 09/25/2012
• Issued: 06/13/2017
• Est. Priority Date: 09/26/2011
• Status: Active Grant

• Current Assignee: Magna Electronics Incorporated (Magna International Incorporated)
• Original Assignee: Magna Electronics Incorporated (Magna International Incorporated)
• Inventors: Kussel, Marcel
• Primary Examiner(s): Teitelbaum, Michael
• Application Number:
  US14/343,937
• Publication Number:
  US 20140232872A1
• Time in Patent Office: 1,722 Days
• CPC Class Codes: B60R 1/00 Optical viewing arrangements; Real-time viewing arrangements for drivers or passengers using optical image capturing systems, e.g. cameras or video systems specially adapted for use in or on vehicles
• CPC Class Codes: B60R 2300/307 virtually distinguishing relevant parts of a scene from the background of the scene
• CPC Class Codes: B60R 2300/8053 for bad weather conditions or night vision
• CPC Class Codes: H04N 23/76 by influencing the image signals

Abstract

A vision system for a vehicle includes an imaging sensor disposed at the vehicle and having an exterior field of view, and an image processor. The imaging sensor captures image data and the image processor is operable to process successive frames of captured image data. Responsive to a determination of a low visibility driving condition, the image processor increases the contrast of the captured images to enhance discrimination of objects in the field of view of the imaging sensor. The image processor may execute a first brightness transfer function on frames of captured image data to enhance the contrast of captured image data, and may execute a second brightness transfer function over successive frames of earlier captured image data and may execute a tone mapping of the earlier captured image data and the currently captured image data to generate a contrast enhanced output image.

Claims

1. A vision system for a vehicle, said vision system comprising:

an imaging sensor disposed at the vehicle and having an exterior field of view, said imaging sensor capturing image data;

an image processor operable to process successive frames of captured image data;

wherein, responsive to a determination of a low visibility driving condition, said image processor increases contrast of features in the captured image data by brightening brighter areas and dampening darker areas of the captured image data, and wherein said image processor increases contrast of features in the captured image data over multiple successive frames of captured image data to enhance discrimination of objects present in the field of view of said imaging sensor; and

wherein said vision system, via image processing of multiple successive frames of captured image data during a determined low visibility driving condition, tracks, from frame to frame, image flow of features caused by movement of the vehicle to enhance detection and identification of objects present in the exterior field of view of said imaging sensor.

2. The vision system of claim 1, wherein said image processor processes captured image data to determine a low visibility driving condition.

3. The vision system of claim 2, wherein said image processor is operable to determine that fog is present in the field of view of said imaging sensor.

4. The vision system of claim 1, wherein said image processor executes a first brightness transfer function on frames of captured image data to enhance contrast of features in captured image data to enhance discrimination of objects present in the field of view of said imaging sensor.

5. The vision system of claim 4, wherein said image processor executes a second brightness transfer function on other frames of captured image data.

6. The vision system of claim 5, wherein said image processor executes tone mapping of multiple frames of captured image data to generate a contrast enhanced output image to enhance discrimination of objects in the field of view of said imaging sensor.

7. The vision system of claim 6, wherein said image processor tracks a detected object over successive frames of captured image data to determine if the detected object is an object of interest in the field of view of said imaging sensor.

8. The vision system of claim 1, wherein said image processor, during processing of captured image data, is responsive at least in part to at least one of a vehicle speed and a vehicle steering angle.

9. The vision system of claim 8, wherein said image processor distinguishes moving objects from non-moving objects responsive at least in part to at least one of a vehicle speed and a vehicle steering angle.

10. The vision system of claim 1, comprising a display for displaying images derived from image data captured by said imaging sensor for viewing by a driver of the vehicle when normally operating the vehicle.

11. The vision system of claim 10, comprising a plurality of imaging sensors disposed at the vehicle and having respective exterior fields of view and capturing image data, wherein said display displays images derived from image data captured by imaging sensors of said plurality of imaging sensors.

12. The vision system of claim 10, wherein said imaging sensor is disposed at a rear portion of the vehicle and has an exterior field of view rearward of the vehicle, and wherein said display displays images derived from image data captured by said imaging sensor during a reversing maneuver of the vehicle.

13. A vision system for a vehicle, said vision system comprising:

a plurality of imaging sensors disposed at the vehicle and having respective exterior fields of view, wherein individual imaging sensors of said plurality of imaging sensors capture image data;

wherein said imaging sensors comprise CMOS imaging sensors;

an image processor operable to process successive frames of captured image data;

wherein, responsive to a determination of a low visibility driving condition, said image processor increases contrast of features in captured image data by brightening brighter areas and dampening darker areas of the captured image data, and wherein said image processor increases contrast of features in the captured image data over multiple successive frames of captured image data to enhance discrimination of objects present in the fields of view of said imaging sensors;

wherein said vision system, via image processing of multiple successive frames of captured image data during a determined low visibility driving condition, tracks, from frame to frame, image flow of features caused by movement of the vehicle to enhance detection and identification of objects present in the exterior field of view of said imaging sensor;

a display for displaying images derived from image data captured by said imaging sensors for viewing by a driver of the vehicle when normally operating the vehicle; and

wherein said display displays images derived from image data captured by said imaging sensors.

14. The vision system of claim 13, wherein said image processor processes captured image data to determine that fog is present in the field of view of at least one of said imaging sensors.

15. The vision system of claim 13, wherein said image processor executes a first brightness transfer function on frames of captured image data to enhance contrast of features in image data captured by one of said imaging sensors, and wherein said image processor executes a second brightness transfer function on other frames of image data captured by said one of said imaging sensors.

16. The vision system of claim 13, wherein said image processor executes tone mapping of multiple frames of captured image data to generate a contrast enhanced output image to enhance discrimination of objects in the field of view of one of said imaging sensors, and wherein said image processor tracks a detected object over successive frames of captured image data to determine if the detected object is an object of interest in the field of view of said one of said imaging sensors.

17. A vision system for a vehicle, said vision system comprising:

an imaging sensor disposed at a rear portion of the vehicle and having an exterior field of view rearward of the vehicle, wherein said imaging sensor captures image data;

wherein said imaging sensor comprises a CMOS imaging sensor;

an image processor operable to process successive frames of captured image data;

wherein, responsive to a determination of a low visibility driving condition, said image processor increases contrast of features in captured image data by brightening brighter areas and dampening darker areas of the captured image data, and wherein said image processor increases contrast of features in the captured image data over multiple successive frames of captured image data to enhance discrimination of objects present in the field of view of said imaging sensor;

wherein said vision system, via image processing of multiple successive frames of captured image data during a determined low visibility driving condition, tracks, from frame to frame, image flow of features caused by movement of the vehicle to enhance detection and identification of objects present in the exterior field of view of said imaging sensor;

a display for displaying images derived from image data captured by said imaging sensor for viewing by a driver of the vehicle when normally operating the vehicle; and

wherein said display displays images derived from captured image data during a reversing maneuver of the vehicle.

18. The vision system of claim 17, wherein said image processor processes captured image data to determine that fog is present in the field of view of said imaging sensor.

19. The vision system of claim 17, wherein said image processor executes a first brightness transfer function on frames of captured image data and wherein said image processor executes a second brightness transfer function on other frames of captured image data.

20. The vision system of claim 17, wherein said image processor executes tone mapping of multiple frames of captured image data to generate a contrast enhanced output image to enhance discrimination of objects in the field of view of said imaging sensor, and wherein said image processor tracks a detected object over successive frames of captured image data to determine if the detected object is an object of interest in the field of view of said imaging sensor.