Lighting Control for HDR Camera

• US 20100328489A1
• Filed: 12/04/2007
• Published: 12/30/2010
• Est. Priority Date: 12/27/2006
• Status: Abandoned Application

• Current Assignee: Continental Automotive GmbH (Continental AG)
• Original Assignee: Continental Automotive GmbH (Continental AG)
• Inventors: Bauer, Jochen, Rieder, Andre, Wiedemann, Christoph
• Application Number:
  US12/521,588
• Publication Number:
  US 20100328489A1
• Time in Patent Office: Days
• US Class Current: 348/229.1
• CPC Class Codes: G06T 2207/20208 High dynamic range [HDR] image processing
• CPC Class Codes: G06T 2207/30256 Lane; Road marking
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation

Abstract

A method for matching the sensitivity characteristic of an image converter to the light-intensity distribution of an optical image which is projected onto the photosensitive surface of the image converter. There are provided steps for creating a frequency distribution of the image signal values in the optical image converted by the image converter, for determining one or more quantiles of the frequency distribution of the image signal values, and for creating a adapted parameter set of setting values of the image converter on the basis of the specific quantile or quantiles of the frequency distribution.

Claims

1-16. -16. (canceled)

17. A method of adapting a sensitivity characteristic of an image converter to a light-intensity distribution of an optical image projected onto a photosensitive surface of the image converter, the method which comprises:

creating a frequency distribution of image signal values in the optical image converted by the image converter;

determining at least one first quantile and a second quantile of the frequency distribution of the image signal values, with an order of the second quantile being higher than an order of the first quantile;

determining a frequency distribution of light intensities on the photosensitive surface of the image converter by using a relationship, determined by a current parameter set of setting values of the image converter, between light intensities on the photosensitive surface and the image signal values output by the image converter;

creating an adapted parameter set of setting values of the image converter defined to match the first quantile of the frequency distribution of the image signal values resulting from the determined frequency distribution of the light intensities to one target value and to match the second quantile of the frequency distribution to a second target value; and

setting the setting values corresponding to the adapted parameter set.

18. The method according to claim 17, wherein the adapted parameter set comprises at least one operating mode setting value for setting an operating mode of the image converter.

19. The method according to claim 17, wherein the adapted parameter set comprises values for setting offset, lighting time, and gain of the image converter.

20. The method according to claim 17, which further comprises determining an operating mode setting value on the basis of at least one additional quantile.

21. The method according to claim 20, wherein an order of the at least one additional quantile is higher than the order of the first quantile and lower than the order of the second quantile.

22. The method according to claim 17, wherein the step of determining the frequency distribution of the light intensities on the photosensitive surface of the image converter comprises determining the frequency distribution of the light intensities based on a mathematical model via the conversion of a light intensity into an image signal using the current setting values of the image converter as parameters.

23. The method according to claim 22, which comprises generating the adapted parameter set of setting values of the image converter from a previously determined frequency distribution of the light intensities by using the mathematical model as a basis.

24. The method according to claim 22, which further comprises the following method steps:

determining an operating mode setting value on the basis of at least one additional quantile;

comparing a quotient of the light intensity determined for the at least one additional quantile and the light intensity determined for the second quantile with a threshold value; and

if the at least one quotient is greater than the threshold value, switching the image converter into a first operating mode, and

if the at least one quotient is less than or equal to the threshold value, switching the image converter into a second operating mode.

25. The method according to claim 24, wherein the image converter has a linear sensitivity characteristic in the first operating mode.

26. The method according to claim 24, wherein the image converter has a sensitivity characteristic in the second operating mode with at least two linear characteristic segments with different gradients.

27. The method according to claim 21, wherein the adapted parameter set comprises values for setting lin-log timing and lin-log voltage of the image converter determined on the basis of the at least one additional quantile and the second quantile.

28. The method according to claim 21, which comprises determining the values of the adapted parameter set for setting offset, lighting time, and gain of the image converter based on the first quantile and the at least one additional quantile.

29. A device for matching a sensitivity characteristic of an image converter to a light-intensity distribution of an optical image projected onto a photosensitive surface of the image converter, the device comprising:

a histogram device for creating a frequency distribution of image signal values of the optical image converted by the image converter;

a quantile determining device for determining at least two quantiles of the frequency distribution of the image signal values; and

a setting calculation system for creation of an adapted parameter set of setting values of the image converter on a basis of the quantiles of the frequency distribution determined by said quantile determining device, said setting calculation system including a back-calculation system configured to determine the frequency distribution of the light intensities on the photosensitive surface of the image converter;

wherein said histogram device, said quantile determining device, and said setting calculation system are commonly configured to carry out the method according to claim 17.

30. The device according to claim 29, wherein said setting calculation system comprises an operating mode setting mechanism for setting an operating mode of the image converter.

31. The device according to claim 29, wherein said setting calculation system comprises a comparator for comparing at least one quotient of a light intensity determined for an additional quantile and a light intensity determined for the second quantile with a threshold value.

32. A computer program product for matching a sensitivity characteristic of an image converter to a light intensity distribution of an optical image projected onto a photosensitive surface of the image converter, the computer program product comprising:

a series of physically distinguishable states in computer-readable and computer-executable language which, when corresponding instructions are executed on a data processing system, carry out the method according to claim 17.

33. A computer program product for matching a sensitivity characteristic of an image converter to a light intensity distribution of an optical image projected onto a photosensitive surface of the image converter, the computer program product comprising:

a series of physically distinguishable states in computer-readable and computer-executable language which, when corresponding instructions are executed on a data processing system, embody the device according to claim 29.