Vehicle vision system

• US 20030103141A1
• Filed: 09/27/2002
• Published: 06/05/2003
• Est. Priority Date: 12/31/1997
• Status: Active Grant

• Current Assignee: Gentex Corporation, Aptina Imaging Corporation (ON Semiconductor Corporation)
• Original Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Inventors: Fossum, Eric R., Stam, Joseph S., Bechtel, Jon H., Kemeny, Sabrina E.
• Granted Patent: US 7,567,291 B2
• Time in Patent Office: Days
• US Class Current: 348/148
• CPC Class Codes: G07C 5/0891 Video recorder in combination with video camera
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 23/88 for colour balance, e.g. white-balance circuits or colour temperature control
• CPC Class Codes: H04N 5/57 Control of contrast or brightness
• CPC Class Codes: H04N 9/73 Colour balance circuits, e.g. white balance circuits or colour temperature control camera processing pipelines for colour balance H04N23/88

Abstract

A vehicle viewing system including a camera system for generating a signal corresponding to a scene by integrating light from the scene incident on pixel cells having a variable integration time, a display system for presenting a visual representation of the scene, and a processor system operable to determine the camera system integration time based on brightness levels in the scene. The camera system preferably includes and an input attenuating filter to limit light striking the optical array. The processor system includes an image brightness detector to determine overall image brightness and a display control to determine luminance settings for the display system. The processor system may determine the intensity of the display system based on the brightness of the scene, ambient light levels, and glare on the display. The display system includes a display and a display attenuation filter for limiting the intensity as viewed by the operator.

Claims

1. A vehicle viewing system for displaying an image of a scene to a vehicle operator, the system comprising:

a camera system to generate a signal corresponding to the scene by integrating light from the scene incident on pixel cells, the pixel cells having a variable integration time;

a display system to present the image of the scene; and

a processor system in communication with the camera system and the display system, the processor system operable to determine the camera system integration time based on brightness levels in the scene.

2. A vehicle viewing system as in claim 1, wherein the camera system comprises:

an optical sensor; and

a lens system to focus the image of the scene onto the optical sensor.

3. A vehicle viewing system as in claim 2, the camera system further comprising:

a variable input attenuation filter to limit the light from the image which strikes the optical sensor.

4. A vehicle viewing system as in claim 2 wherein the optical sensor is an array of photogate CMOS active pixel sensors.

5. A vehicle viewing system as in claim 2 wherein the optical sensor is operative to implement a plurality of architectures for integrating and processing the image and wherein the processor system is operative to determine the measures of the image brightness and to determine which architectures will be in use based on the image brightness measures.

6. A vehicle viewing system as in claim 2 wherein the optical sensor is operative to reset at least one pixel sensor during an integration period and the processor system is operative to determine if each of the pixel sensors is to be reset and, for each pixel sensor to be reset, the reset time during the integration period.

7. A vehicle viewing system as in claim 2 wherein the optical sensor is operative to produce a digital signal corresponding to the scene.

8. A vehicle viewing system as in claim 7 wherein the digital signal comprises a magnitude and a range for each pixel cell, the range indicative of the integration period used by the pixel cell.

9. A vehicle viewing system as in claim 3 wherein the variable input attenuation filter comprises an electrochromic window.

10. A vehicle viewing system as in claim 1 wherein the processor system comprises an image brightness detector to sample the brightness values of the image produced by the camera system and to determine measures representative of image brightness.

11. A vehicle viewing system as in claim 10 wherein the image brightness detector is operable to determine a histogram of image brightness values for image frames output from the camera system.

12. A vehicle viewing system as in claim 10 wherein the processor system further comprises a display pixel luminance mapping control that uses the image brightness measures to determine luminance settings for the display system.

13. A vehicle viewing system as in claim 1 wherein the processor system is operable to select a curve from a plurality of curves, each curve relating display luminance as a function of image brightness measures, and wherein the processor system is operable to output a display luminance value based on an image brightness value using the selected curve.

14. A vehicle viewing system as in claim 1, wherein the processor system is operable to modify the color balance of the display system so as to reduce the relative amount of blue light in dim ambient light conditions.

15. A vehicle viewing system as in claim 1, wherein the display system comprises:

a display for emitting light; and

a display variable attenuation filter for limiting the light emitted from the display.

16. A vehicle viewing system as in claim 15, wherein the display variable attenuation filter is an electrochromic window.

17. A vehicle viewing system as in claim 1 further comprising:

an ambient light sensor for detecting the level of ambient light; and

a control logic for determining display system brightness based on the level of ambient light.

18. A vehicle viewing system as in claim 1 further comprising:

a direct glare sensor for detecting the level of glare seen on the display system; and

a control logic for determining display system brightness based on the level of glare seen on the display system.

19. A system for determining brightness levels in an image developed by a vehicle viewing system, the image composed of a plurality of digitized pixel values, the system comprising:

means for reading each of the plurality of digitized pixel values;

logic for determining into which of a plurality of ranges each of the digitized pixel values falls;

a counter corresponding to each of the plurality of ranges; and

a controller in communication with the means for reading values, the range determination logic and the counters, the controller operative to read a value, route the value through the determination logic, increment the corresponding counter, and repeat for each value.

20. A system for determining a luminance setting for each of a plurality of display pixels in a vehicle viewing system, wherein each display pixel represents a corresponding image pixel, and each image pixel having a brightness level, the system comprising:

means for determining a histogram from image pixel brightness levels; and

a logic for determining the luminance for each display pixel based on the brightness of the corresponding image pixel and the histogram.

21. A system for determining luminance settings of claim 20 wherein the logic for determining the luminance for each display pixel is a memory with an address determined from the image brightness histogram and the corresponding image pixel brightness.