Autonomous glare removal technique

Patent metadata

Field	Value
Publication number	US-11388350-B2
Application number	US-202017133600-A
Country	US
Kind code	B2
Filing date	Dec 23, 2020
Priority date	Dec 27, 2019
Publication date	Jul 12, 2022
Grant date	Jul 12, 2022

Abstract

A method is presented for reducing glare in images captured by an imaging system. As a starting point, multiple images of a scene are captured by an imaging system to form a set of images, where the imaging system includes a voltage tunable polarizer and each image in the set of images is captured with the voltage tunable polarizer set at a different polarization angle. The method further includes: partitioning each image in the set of images into a plurality of segments; for corresponding segments in the set of images, determining an amount of change in intensity across corresponding segments of images; quantifying the amount of intensity change for each image in the set of images; and identifying a given image from the set of images based on the quantified amount of intensity change, where the given image has least amount of intensity change amongst the set of images.

First claim

What is claimed is:

1. A method for reducing glare in images captured by an imaging system, comprising:
capturing, by an imaging system, multiple images of a scene to form a set of images, where the imaging system includes a voltage tunable polarizer and each image in the set of images is captured with the voltage tunable polarizer set at a different polarization angle;
partitioning, by a signal processor of the imaging system, each image in the set of images into a plurality of segments;
for corresponding segments in the set of images, determining, by the signal processor, an amount of change in intensity across corresponding segments of images in the set of images;
quantifying, by the signal processor, the amount of intensity change for each image in the set of images;
identifying, by the signal processor, a given image from the set of images based on the quantified amount of intensity change, where the given image has least amount of intensity change amongst the set of images.

2. The method of claim 1 further comprises partitioning each image in the set of images such that each segment includes data from three or more pixels of an imager of the imaging system.

3. The method of claim 1 further comprises, for each segment in each image in the set of images, computing an average intensity for pixels comprising a given segment, and determining an amount of change in intensity across corresponding segments of images by calculating a percentage change in the average intensity across corresponding segments.

4. The method of claim 3 wherein quantifying the amount of intensity change for each image further comprises assigning a weighting factor to each segment in the plurality of segments based on the amount of change in intensity across corresponding segments of images, constructing a return matrix, multiplying the weighting factor for each segment by the return matrix to yield a result matrix, and determining the given image from the result matrix, where values of the return matrix indicate image with lowest intensity value for the corresponding segment in the set of images.

5. The method of claim 1 further comprises displaying the given image on a display device.

6. The method of claim 1 further comprises inputting the given image into a control system for an autonomous vehicle and controlling the autonomous vehicle in part based on the given image.

7. The method of claim 4 further comprises
identifying a particular segment from the plurality of segments which exhibits glare;
identifying a particular image from the set of images, where the particular image includes the particular segment with lowest average intensity for pixels comprising the particular segment;
determining a polarization angle at which the particular image was captured;
capturing additional images of a scene with the imaging system, where the additional images are captured at polarization angles centered around the polarization angle at which the particular image was captured and separation between the polarization angles is less than the separation at which the multiple images were captured.

8. The method of claim 7 further comprises
partitioning each image in the additional images into the plurality of segments;
for the particular segment in each additional image, determining an amount of change in intensity across pixels comprising the particular segment; and
selecting the particular segment from the additional images, where the selected particular segment has lowest amount of change in intensity across pixels comprising the selected particular segment; and
constructing a final image in part using the selected particular segment.

9. The method of claim 1 wherein the voltage tunable polarizer includes: a first quarter waveplate configured to receive the light from a scene; a first liquid crystal retarder positioned adjacent to the first quarter waveplate and configured to receive the light passing through the first quarter waveplate; a linear polarizer having an incoming surface positioned adjacent to the first liquid crystal retarder and configured to receive the light passing through the first liquid crystal retarder; a second liquid crystal retarder positioned adjacent to an outgoing surface of the linear polarizer and configured to receive the light passing through the linear polarizer; and a second quarter waveplate positioned adjacent to the second liquid crystal retarder and configured to receive the light passing through the second liquid crystal retarder, where the incoming surface of the linear polarizer opposes the outgoing surface of the linear polarizer.

10. A method for reducing glare in images captured by an imaging system, comprising:
capturing, by an imaging system, multiple images of a scene to form a set of images, where the imaging system includes a voltage tunable polarizer and each image in the set of images is captured with the voltage tunable polarizer set at a different polarization angle;
partitioning, by a signal processor of the imaging system, each image in the set of images into a plurality of segments;
for corresponding segments in the set of images, determining, by the signal processor, an amount of change in intensity across corresponding segments of images in the set of images;
identifying a particular segment from the plurality of segments which exhibits glare;
identifying a particular image from the set of images, where the particular image includes the particular segment with lowest average intensity for pixels comprising the particular segment;
determining a polarization angle at which the particular image was captured;
capturing additional images of a scene with the imaging system, where the additional images are captured at polarization angles centered around the polarization angle at which the particular image was captured and separation between the polarization angles is less than the separation at which the multiple images were captured.

11. The method of claim 10 further comprises partitioning each image in the set of images such that each segment includes data from three or more pixels of an imager of the imaging system.

12. The method of claim 10 further comprises, for each segment in each image in the set of images, computing an average intensity for pixels comprising a given segment, and determining an amount of change in intensity across corresponding segments of images by calculating a percentage change in the average intensity across corresponding segments.

13. The method of claim 10 further comprises
partitioning each image in the additional images into the plurality of segments;
for the particular segment in each additional image, determining an amount of change in intensity across pixels comprising the particular segment; and
selecting the particular segment from the additional images, where the selected particular segment has lowest amount of change in intensity across pixels comprising the selected particular segment; and
constructing a final image in part using the selected particular segment.

14. The method of claim 13 wherein constructing a final image further comprises:
quantifying, by the signal processor, the amount of intensity change for each image in the set of images;
identifying, by the signal processor, a given image from the set of images based on the quantified amount of intensity change, where the given image has least amount of intensity change amongst the set of images;
replacing segment corresponding to the selected particular segment in the given image with the selected particular segment to form the final image.

15. An imaging system, c

Assignees

• Univ Michigan Regents

Inventors

• Lee Somin Eunice
• Liu Yunbo
• Park Young Geun

Classifications

• H04N23/75 Primary

  by influencing optical camera components · CPC title

• H04N23/55 Primary

  Optical parts specially adapted for electronic image sensors; Mounting thereof · CPC title

• H04N23/60

  Control of cameras or camera modules · CPC title

• H04N5/2254

  Electricity · mapped topic

• H04N5/238 Primary

  Electricity · mapped topic