CAMERA ARRANGEMENT FOR A VEHICLE AND METHOD FOR CALIBRATING A CAMERA AND FOR OPERATING A CAMERA ARRANGEMENT

• US 20150109445A1
• Filed: 05/13/2011
• Published: 04/23/2015
• Est. Priority Date: 05/13/2011
• Status: Active Grant

• Current Assignee: Valeo Schalter und Sensoren GmbH (Valeo SE)
• Original Assignee: Valeo Schalter und Sensoren GmbH (Valeo SE)
• Inventors: Wedajo, Brouk, Quelquejay, Yan, Ahiad, Samia, Robert-Landry, Caroline, Petit, Julia
• Granted Patent: US 10,079,979 B2
• Time in Patent Office: Days
• US Class Current: 348/148
• CPC Class Codes: B60R 2300/402 Image calibration
• CPC Class Codes: G01J 1/4204 with determination of ambient light solar light G01J2001/4266
• CPC Class Codes: G03B 17/18 Signals indicating condition of a camera member or suitability of light indicating depth of field G03B13/30
• CPC Class Codes: G03B 43/00 Testing correct operation of photographic apparatus or parts thereof
• CPC Class Codes: G03B 7/08 Control effected solely on the basis of the response, to the intensity of the light received by the camera, of a built-in light-sensitive device
• CPC Class Codes: H04N 17/002 for television cameras
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation

Abstract

The invention relates to a camera arrangement for a vehicle, comprising a camera (12), wherein by means of the camera arrangement a brightness of the surroundings of the camera is determinable. The camera arrangement comprises a storage device (38) in which is stored at least one brightness reference value (34) capturable by the camera. This reference value (34) is correlated with a corresponding value (36) indicative of a photometric quantity measurable by means of a photometer (14) at this brightness. An evaluation unit of the camera arrangement is designed for comparing a brightness value determined by the camera with the brightness reference value (34). Furthermore, the invention relates to a method for calibrating a camera (12) and for operating a camera arrangement.

Claims

1. A camera arrangement for a vehicle, comprising:

a camera, wherein by means of the camera arrangement a brightness of the surroundings of the camera is determinable,

wherein, the camera arrangement comprises a storage device in which is stored at least one brightness reference value capturable by the camera, which is correlated with a corresponding value indicative of a photometric quantity measurable by means of a photometer at this brightness, and

wherein the camera arrangement comprises an evaluation unit which is designed for comparing a brightness value determined by the camera with the brightness reference value.

2. The camera arrangement according to claim 1, wherein, the brightness determinable by the camera arrangement takes into account brightness values per pixel of a picture capturable by the camera.

3. The camera arrangement according to claim 1, wherein, at least two brightness reference values which are capturable by the camera are stored in the storage device, wherein the reference values correspond to different gamma values of the camera.

4. The camera arrangement according to claim 1, wherein at least two brightness reference values which are capturable by the camera are stored in the storage device, wherein the reference values correspond to different integration times during which a picture sensor of the camera accumulates charge carriers as the camera captures a picture.

5. The camera arrangement according to claim 4, wherein a plurality of brightness reference values which are capturable by the camera are stored in a lookup-table provided in the storage device together with the corresponding values indicative of the photometric quantity.

6. The camera arrangement according to claim 5, wherein a portion of the lookup-table to be focused on is pre-determined in dependence on a preset gamma value and/or a preset integration time of the camera.

7. The camera arrangement according to claim 1, wherein the photometric quantity is indicative of the brightness perceivable by the human eye.

8. The camera arrangement according to claim 1, wherein the at least one brightness reference value is stored as greyscale value.

9. A method for calibrating a camera for a vehicle, comprising:

exposing the camera and a photometer are exposed to a light source;

measuring, using the photometer, a photometric quantity indicative of the brightness of the light source,

wherein at least one brightness value determined by the camera is correlated as brightness reference value with the photometric quantity measured by the photometer; and

storing the reference value of the brightness and a corresponding value indicating the photometric quantity are stored in a storage device.

10. Method according to claim 9, wherein a plurality of brightness reference values and corresponding values are stored in a lookup-table provided in the storage device.

11. The method according to claim 9, wherein the camera and the photometer are exposed to the light source simultaneously.

12. The method according claim 9, wherein the camera and the photometer capture respective angles of view of the same quantity.

13. A method for operating a camera arrangement comprising a camera for a vehicle, comprising:

determining, using the camera arrangement a brightness of the surroundings of the camera;

accessing a storage device of the camera arrangement, in which at least one brightness reference value is stored, which is capturable by the camera;

correlating the at least one reference value with a corresponding value indicative of a photometric quantity measured by a photometer at this brightness; and

comparing, by an evaluation unit of the camera arrangement, a brightness value determined by the camera with the at least one brightness reference value.

14. The method according to claim 13, wherein the brightness reference value is obtained by a calibration method according to claim 9.