Imaging system and method with dynamic brightness control

• US 6,734,904 B1
• Filed: 07/23/1998
• Issued: 05/11/2004
• Est. Priority Date: 07/23/1998
• Status: Expired due to Term

• Current Assignee: Bendix Commercial Vehicle Systems LLC (Estate of Heinz Hermann Thiele), Daimler-Benz AG (Mercedes-Benz Group AG)
• Original Assignee: Iteris Incorporated, Daimler-Benz AG (Mercedes-Benz Group AG)
• Inventors: Boon, Cathy L., Mehring, Steffi
• Primary Examiner(s): Christensen, Andrew
• Assistant Examiner(s): NGUYEN, LUONG TRUNG
• Application Number:
  US09/121,800
• Time in Patent Office: 2,119 Days
• Field of Search: 348/223, 348/234, 348/295, 348/362, 348/363, 348/364, 348/352, 348/223.1, 348/149, 348/148, 340/937, 340/933, 340/935, 340/936, 382/274
• US Class Current: 348/234
• CPC Class Codes: H04N 7/183 for receiving images from a single remote source

Abstract

An imaging system with brightness control includes an image capture subsystem and an image control block and is adapted for use in conjunction with an image processing application. The image capture subsystem receives an image and converts this image into digital image data. The digital signal is then stored in a video buffer for access by the image control block. The image control block provides brightness control of an image sensor in the image control subsystem to optimize the brightness of the desired area of interest in the image relative to the background. In one application, the imaging system is used in conjunction with a lane tracking system image processing application to detect roadway lane markings from a moving vehicle.

Claims

1. A method of brightness control for an image sensor, said method comprising:

receiving image data of an image from said image sensor;

determining pixel intensities in a region of interest comprising a portion of the image including roadway lane marker(s);

estimating the number and intensity of pixels corresponding to the lane marker(s) in said region of interest based on prior knowledge of the lane marker(s);

discarding the pixels corresponding to the lane marker(s) to derive pixels comprising the background portion of the region of interest surrounding the lane marker(s);

detecting the brightness level of said pixels comprising the background portion of the region of interest;

determining an adjusted brightness level of said background portion of the region of interest, wherein the brightness of said lane marker(s) is optimized in relation to said background portion of the region of interest; and

controlling said image sensor to alter said brightness level of said background portion of the region of interest to said adjusted brightness level.

2. A method as set out in claim 1, wherein said portion of the image corresponds to the background.

3. A method as set in claim 1, wherein said image sensor comprises an imaging chip having exposure/gain settings and wherein said controlling alters said exposure/gain settings.

4. A method as set out in claim 1, wherein said image sensor comprises an imaging chip having exposure/gain settings and having an on chip/exposure gain control algorithm wherein said controlling alters parameters used by said on chip exposure/gain control algorithm to effect alteration of said exposure/gain settings.

5. An imaging system with dynamic brightness control, said system comprising:

an image sensor for providing image data of a scene;

means for automatically determining pixel intensities in a region of interest comprising a portion of the image including roadway lane marker(s);

means for automatically estimating the number and intensity of pixels corresponding to the lane marker(s) from said pixel intensities in the region of interest based on prior knowledge of the lane marker(s);

means for discarding the pixels corresponding to the lane marker(s) to derive pixels comprising the background portion of the region of interest surrounding the lane marker(s);

means for detecting a brightness level of said pixels comprising the background portion of the region of interest surrounding the lane marker(s);

means for determining an adjusted brightness level of said background portion of the region of interest surrounding the lane marker(s), wherein the brightness of said lane markers is optimized in relation to said background portion of the region of interest surrounding the lane marker(s); and

control means, coupled to the image sensor, for controlling the image sensor to alter said brightness level of said background portion of the region of interest surrounding the lane marker(s) to said adjusted brightness level.

6. The imaging system as set out in claim 5, wherein said image sensor comprises an imaging chip for detecting an image and providing image signals.

7. The imaging system as set out in claim 5, wherein the imaging chip includes adjustable exposure/gain settings and wherein the control means adjusts the exposure/gain settings of the imaging chip.

8. The imaging system as set out in claim 6, wherein the imaging chip includes adjustable exposure/gain settings and wherein the imaging chip further includes an on chip exposure/gain control algorithm and wherein the control means adjusts the parameter used by said on chip exposure/gain control algorithm to effect alteration of the exposure/gain settings of the imaging chip.

9. The imaging system as set out in claim 6, wherein said imaging sensor further includes a video buffer for storing digital image data.

10. The imaging system as set out in claim 5, wherein said portion of the image comprises the background portion surrounding the object(s) of interest and wherein said adjusted brightness level is chosen to maintain the brightness level of said background at or below a desired threshold.

11. The imaging system as set out in claim 7, wherein the control means dynamically controls the imaging chip settings on a frame by frame basis.

12. The imaging system as set out in claim 8, wherein the control means dynamically controls the imaging chip settings on a frame by frame basis.

13. The imaging system as set out in claim 5, wherein the means for detecting only examines the image data corresponding to a portion of the image data having a brightness level below a threshold value.