Vehicle vision system with color correction

• US 10,230,873 B2
• Filed: 01/24/2018
• Issued: 03/12/2019
• Est. Priority Date: 11/07/2011
• Status: Active Grant

• Current Assignee: Magna Electronics Incorporated (Magna International Incorporated)
• Original Assignee: Magna Electronics Incorporated (Magna International Incorporated)
• Inventors: Wierich, Thomas
• Primary Examiner(s): Truong, Nguyen T
• Application Number:
  US15/878,764
• Publication Number:
  US 20180152604A1
• Time in Patent Office: 412 Days
• Field of Search: 348148
• CPC Class Codes: B60R 11/04 Mounting of cameras operative during drive; Arrangement of controls thereof relative to the vehicle
• CPC Class Codes: B60R 2300/30 characterised by the type of image processing
• CPC Class Codes: B60R 2300/802 for monitoring and displaying vehicle exterior blind spot views
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 2207/30252 Vehicle exterior; Vicinity of vehicle
• CPC Class Codes: G06T 7/90 Determination of colour characteristics
• CPC Class Codes: H04N 1/6027 Correction or control of colour gradation or colour contrast H04N1/6058 takes precedence
• CPC Class Codes: H04N 23/12 with one sensor only
• CPC Class Codes: H04N 23/698 for achieving an enlarged field of view, e.g. panoramic image capture
• CPC Class Codes: H04N 23/88 for colour balance, e.g. white-balance circuits or colour temperature control

Abstract

A method for processing color image data captured by a vehicular camera to correct for color error includes providing a color camera with an imaging array having a plurality of photosensors, disposing one or more spectral filters at or in front of photosensors of the imaging array, and disposing the color camera at a vehicle so as to have a field of view exterior of the vehicle. An image processor is provided that processes image data captured by the color camera. The processing of image data includes processing image data in a color correction loop to correct color variation due to lighting conditions so that images derived from captured image data are color corrected. The color correction accounts for color of light emitted by an illumination source.

Claims

1. A method for processing color image data captured by a vehicular camera disposed at a vehicle to correct for color error, said method comprising:

providing a color camera comprising an imaging array having a plurality of photosensors;

disposing one or more spectral filters at or in front of photosensors of the plurality of photosensors of the imaging array;

disposing the color camera at a vehicle so as to have a field of view exterior of the vehicle;

providing an image processor;

capturing image data with the color camera;

providing captured image data to the image processor;

processing image data captured by the color camera via the image processor;

wherein said processing of image data comprises processing image data in a color correction loop to correct color variation due to lighting conditions so that images derived from captured image data are color corrected; and

wherein the color correction accounts for color of light emitted by an illumination source.

2. The method of claim 1, wherein said processing of image data utilizes pre-determining illumination scenarios.

3. The method of claim 2, wherein said processing of image data comprises pre-determining illumination scenarios, such that, when a particular illumination scenario is determined, the image processor can utilize a predetermined polynomial equation to calculate data points along an x-y color curve based on the determined particular illumination scenario.

4. The method of claim 1, wherein disposing the color camera comprises disposing the color camera at a rear of the vehicle so as to have a field of view rearward of the vehicle.

5. The method of claim 4, comprising providing the illumination source at the rear of the vehicle.

6. The method of claim 1, wherein a hysteresis loop corrects color variation due to lighting conditions so that white colors are properly determined to be along a Planckian Locus.

7. The method of claim 1, wherein said processing of image data comprises utilization of a color correction algorithm that includes a color correction matrix algorithm.

8. The method of claim 7, wherein the color correction algorithm comprises the color correction matrix algorithm and a histogram algorithm to determine a color correction for the captured image data.

9. The method of claim 7, wherein said processing of image data comprises receiving an output from a histogram algorithm and, after processing the output, generating an output that is used as an input to the color correction matrix algorithm.

10. The method of claim 9, wherein an output of the color correction matrix algorithm is used as an input to the histogram algorithm.

11. The method of claim 10, comprising repeating the color correction matrix algorithm and the histogram algorithm until a desired level of color correction is determined.

12. The method of claim 11, wherein the color correction matrix algorithm and the histogram algorithm repeatedly operate to migrate a plurality of data points representative of white points through a color room towards a center line of white points along a Planckian locus.

13. The method of claim 12, wherein the histogram algorithm does not use the data points when an RGB component of the data points exceeds a threshold fraction of full scale.

14. The method of claim 13, wherein the threshold fraction of full scale of the RGB component is ninety percent.

15. The method of claim 1, wherein the image processor includes polynomial equations representative of light plots in white illuminated illumination scenarios, and wherein the image processor, responsive to a determination that captured image data is representative of a typical illumination scenario, uses a corresponding polynomial equation to determine a desired point along a polynomial equation without having to interpolate between data points.

16. A method for processing color image data captured by a vehicular camera disposed at a vehicle to correct for color error, said method comprising:

providing a color camera comprising an imaging array having a plurality of photosensors;

disposing one or more spectral filters at or in front of photosensors of the plurality of photosensors of the imaging array;

disposing the color camera at a vehicle so as to have a field of view exterior of the vehicle;

providing an illumination source at the vehicle;

providing an image processor;

capturing image data with the color camera with the illumination source activated;

providing captured image data to the image processor;

processing image data captured by the color camera via the image processor;

wherein said processing of image data comprises processing image data in a color correction loop to correct color variation due to lighting conditions so that images derived from captured image data are color corrected;

wherein said processing of image data comprises utilization of a color correction matrix algorithm; and

wherein the color correction accounts for color of light emitted by the illumination source.

17. The method of claim 16, wherein said processing of image data comprises utilization of a color correction algorithm that includes a color correction matrix algorithm, and wherein the color correction algorithm comprises the color correction matrix algorithm and a histogram algorithm to determine a color correction for the captured image data.

18. The method of claim 16, wherein the image processor, responsive to a determination that captured image data is representative of a typical illumination scenario, uses a corresponding polynomial equation to determine a desired point along a polynomial equation without having to interpolate between data points.

19. A method for processing color image data captured by a vehicular camera disposed at a vehicle to correct for color error, said method comprising:

providing a color camera comprising an imaging array having a plurality of photosensors;

disposing one or more spectral filters at or in front of photosensors of the plurality of photosensors of the imaging array;

disposing the color camera at a rear of a vehicle so as to have a field of view rearward of the vehicle;

providing an image processor;

capturing image data with the color camera;

providing captured image data to the image processor;

processing image data captured by the color camera via the image processor;

wherein said processing of image data comprises processing image data in a color correction loop to correct color variation due to lighting conditions so that images derived from captured image data are color corrected;

wherein said processing of image data comprises pre-determining illumination scenarios, such that, when a particular illumination scenario is determined, the image processor can calculate data points along an x-y color curve based on the determined particular illumination scenario; and

wherein the color correction accounts for color of light emitted by an illumination source.

20. The method of claim 19, wherein, when a particular illumination scenario is determined, the image processor utilizes a predetermined polynomial equation to calculate data points along the x-y color curve based on the determined particular illumination scenario.