Glaring reduction for dynamic rearview mirror

Patent metadata

Field	Value
Publication number	US-9307207-B2
Application number	US-201314040952-A
Country	US
Kind code	B2
Filing date	Sep 30, 2013
Priority date	Jan 7, 2013
Publication date	Apr 5, 2016
Grant date	Apr 5, 2016

Abstract

A method for generating a glare-reduced image from images captured by a camera device of a subject vehicle includes obtaining a short-exposure image and a long-exposure image and generating a resulting high dynamic range image based on the short-exposure and long-exposure images. Pixel values are monitored within both the short- and long-exposure images. A light source region is identified within both the short- and long-exposure images based on the monitored pixel values. A glaring region is identified based on the identified light source region and one of calculated pixel ratios and calculated pixel differences between the monitored pixel values of the long- and short-exposure images. The identified glaring region upon the resulting high dynamic range image is modified with the identified light source region within the short-exposure image. The glare-reduced image is generated based on the modified identified glaring region upon the resulting HDR image.

First claim

The invention claimed is:

1. Method for generating a glare-reduced image from images captured by a camera device of a subject vehicle, comprising:
obtaining a short-exposure image and a long-exposure image captured by the camera device;
generating a resulting high dynamic range (HDR) image based on the short-exposure and long-exposure images;
monitoring pixel values within both the short-exposure and the long-exposure images;
identifying a light source region within both the short-exposure and the long-exposure images based on the monitored pixel values;
calculating one of pixel ratios and pixel differences between the monitored pixel values of the long-exposure and the short-exposure images;
identifying a glaring region based on the identified light source region within both the short-exposure and the long-exposure images and one of calculated pixel ratios and calculated pixel differences;
modifying the identified glaring region upon the resulting HDR image with a short-exposure region corresponding to the identified light source region within the unmodified short-exposure image, comprising increasing the portion of the unmodified identified light source region within the short-exposure image and decreasing the portion of the identified light source region within the long-exposure image applied thereto; and
generating a glare-reduced image based on the modified identified glaring region upon the resulting HDR image.

2. The method of claim 1 , wherein the short-exposure and the long-exposure images are simultaneously obtained when the camera device utilizes a split sub-pixel imaging chip incorporating a short-exposure sub-pixel and a long-exposure sub-pixel for each pixel.

3. The method of claim 1 , wherein the short-exposure and the long-exposure images are obtained during different time periods when the camera device utilizes an imaging chip having an array of pixels each adjustable between one of a short-exposure time and a long-exposure time at a time.

4. The method of claim 3 , wherein obtaining the short-exposure and long-exposure images comprises:
for each pixel, utilizing the short-exposure time during a first time period to obtain the short-exposure image and utilizing the long-exposure time during a second time period to obtain the long-exposure image.

5. The method of claim 1 , wherein identifying the light source region within both the short-exposure and the long-exposure images comprises:
comparing the monitored pixel values to a light source threshold; and
identifying the light source region within both the short-exposure and the long-exposure images corresponding to a region wherein the monitored pixel values exceed the light source threshold.

6. The method of claim 1 , wherein the monitored pixel values comprise at least an intensity value for each pixel within both the short-exposure and the long-exposure images.

7. The method of claim 6 , wherein the monitored pixel values further comprise color information for each pixel within both the short-exposure and the long-exposure images.

8. The method of claim 1 , wherein identifying the glaring region comprises:
comparing calculated pixel ratios to a glaring threshold;
identifying the glaring region corresponding to a region around a perimeter of the identified light source where calculated pixel ratios exceed the glaring threshold.

9. The method of claim 1 , wherein identifying the glaring region comprises:
comparing calculated pixel differences to a glaring threshold;
identifying the glaring region corresponding to a region around a perimeter of the identified light source where calculated pixel differences exceed the glaring threshold.

10. The method of claim 1 , wherein generating the glare-reduced image further comprises:
in all other regions not identified as the glaring region, applying HDR processing for enhancing image quality for the resulting HDR image.

11. The method of claim 10 , wherein applying HDR processing includes at least one of applied tone mapping, adjusted exposure time, gamma correction and pixel bit-depth conversion.

12. The method of claim 1 , wherein modifying the identified glaring region upon the resulting HDR image comprises:
modifying the identified glaring region to include a portion of the identified light source region within the short-exposure image that is greater than a portion of the identified light source region within the long-exposure region.

13. The method of claim 12 . wherein the portion of the identified light source region within the short-exposure image gradually decreases from a center of the identified glaring region to a periphery of the identified glaring region.

14. Method for generating a glare-reduced image from images captured by a camera device of a subject vehicle, comprising:
obtaining a short-exposure image and a long-exposure image captured by the camera device;
generating a resulting high dynamic range (HDR) image based on the obtained short-exposure and long-exposure images;
monitoring pixel values within both the short-exposure and the long-exposure images, each pixel value comprising at least an intensity value;
identifying a light source region within both the short-exposure and the long-exposure images based on the monitored pixel values;
identifying a glaring region around a perimeter of the identified light source based on the identified light source region within both the short-exposure and the long-exposure images and the calculated pixel ratios between the monitored pixel values of the long-exposure and the short-exposure images;
modifying the identified glaring region upon the resulting HDR image with a short-exposure region corresponding to the respective identified light source region within the unmodified short-exposure image, comprising increasing the portion of the unmodified identified light source region within the short-exposure image and decreasing the portion of the identified light source region within the long-exposure image applied thereto;
applying HDR processing for obtaining optimal image quality for the resulting HDR image in all other regions not identified as the glaring region; and
generating a glare-reduced image based on the modified identified glaring region upon the resulting HDR image.

15. The method of claim 14 , wherein the identified light source region includes one of a direct light source region and a reflective light source region.

16. The method of claim 14 , wherein obtaining the short-exposure and the long-exposure images comprises one of:
spatially obtaining the short-exposure and the long-exposure images simultaneously when the camera device utilizes a split sub-pixel imaging chip incorporating a short-exposure sub-pixel and a long-exposure sub-pixel for each pixel; and
temporally obtaining the short-exposure and the long-exposure images during different time periods when the camera device utilizes an imaging chip having an array of pixels each adjustable between one of a short-exposure time and a long-exposure time at a time.

17. The method of claim 14 , wherein identifying the light source region within both the short-exposure and the long-exposure images based on the monitored pixel values comprises:
comparing the monitored pixel values to a light source threshold, the light source threshold comprising a minimum intensity indicative of a light source;
identifying the light source region within both the short-exposure and the long-exposure images corresponding to a region wherein the monitored pixel values exceed the light source threshold.

18. The

Assignees

• Gm Global Tech Operations Inc

Inventors

• Zhang Wende
• Wang Jinsong
• Lybecker Kent S
• Piasecki Jeffrey S
• Frakes Ryan M
• Hester Travis S

Classifications

• H04N23/741 Primary

  by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors · CPC title

• H04N9/045 Primary

  Electricity · mapped topic

• H04N5/2355

  Electricity · mapped topic