Method and device for controlling the exposure of a camera

• US 20060269271A1
• Filed: 01/20/2004
• Published: 11/30/2006
• Est. Priority Date: 08/14/2003
• Status: Abandoned Application

• Current Assignee: Conti Temic Microelectronic GmbH (Continental AG)
• Original Assignee: Conti Temic Microelectronic GmbH (Continental AG)
• Inventors: Kokel, Dieter
• Application Number:
  US10/568,379
• Publication Number:
  US 20060269271A1
• Time in Patent Office: Days
• US Class Current: 396/213
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 23/76 by influencing the image signals

Abstract

Disclosed is an exposure control method for a camera with at least one image sensor in which an image brightness set-point is preset and control is carried out with reference to this image brightness set-point it is provided to adjust the gradient of a substantially linear dependence of image brightness on illumination.

Claims

1-9. -9. (canceled)

10. An exposure control method for a camera with at least one image sensor in which an image brightness set-point (Hsoll) is preset and control is carried out with reference to this image brightness set-point (Hsoll), the method comprising:

adjusting a gradient (α

) by controlling at least one of an integration time or an intensification of an image sensor;

determining a new gradient from an initial gradient α

1, image brightness set-point Hsoll and current image brightness Hist according to the formula;

α

2=α

1*Hsoll/Hist.

11. A method according to claim 10, wherein image brightness Hist is compared with a tolerance range (Hsoll1, Hsoll2) around image brightness set-point (Hsoll);

and a new gradient α

2 is preset in one control step only if image brightness Hist lies outside said tolerance range (Hsoll1, Hsoll2) around image brightness set-point (Hsoll).

12. A method according to claim 10, wherein a preset characteristic of a characteristic (K) of the dependence of image brightness (H) on illumination (B) is taken into consideration when determining new gradient α

2.

13. A method according to claim 12, wherein characteristic K does not run through origin U and new gradient α

2 is determined considering at least one offset value Offs1 according to the following formula;

α

2=α

1*(Hsoll−

Offs1)/(Hist−

Offs1).

14. A method according to claim 13, wherein for each gradient (α

2, α

1) a respective offset value (Offs1, Offs2) is provided and new gradient α

2 is determined considering said respective offset values according to the following formula;

α

2=α

1*(Hsoll−

Offs1)/(Hist−

Offs2).

15. An exposure control device for a camera with at least one image sensor in which an image brightness set-point Hsoll is preset and control is carried out with reference to this image brightness set-point Hsoll, the device comprising:

a computer for evaluating images and for substantially controling exposure and image brightness.

16. A device according to claim 15, wherein specific, relevant pixels are selected to measure an image brightness and image brightness control is substantially carried out with reference to selected regions.

17. A device according to claim 15, wherein the computer uses an adjusted sensitivity for the current image brightness of a scene the image of which is being formed and for providing this value to a system.

18. A device according to claim 15, wherein the device is used in vehicle environment monitoring camera for motor vehicles.