Method and system for video processing to remove noise from a digital video sequence containing a modulated light signal

Patent metadata

Field	Value
Publication number	US-9888203-B2
Application number	US-201615093120-A
Country	US
Kind code	B2
Filing date	Apr 7, 2016
Priority date	Jul 26, 2011
Publication date	Feb 6, 2018
Grant date	Feb 6, 2018

Abstract

In one aspect, the present disclosure relates to a method for removing noise from a digital video sequence containing a modulated light signal emitted from a beacon light source. In some embodiments, the method includes electronically receiving, by an image sensor of a device, a digital video sequence of a scene, calculating noise from the digital video sequence, wherein the noise comprises information within the digital video sequence corresponding to the un-modulated illumination of the scene, reducing the noise from the digital video sequence to obtain an isolated digital video sequence of the modulated illumination of the scene, and demodulating the emitted light signal from the isolated digital video sequence.

First claim

What is claimed is:

1. A method comprising:
electronically receiving, by an image sensor of a device, a still image of a scene, wherein:
the scene comprises both modulated illumination emitted by a beacon light source and un-modulated illumination; and
the still image comprises a plurality of pixel values, each of the plurality of pixel values being for a given point in the still image;

calculating noise from the still image, wherein the noise comprises information within the still image corresponding to the un-modulated illumination of the scene;
removing the calculated noise from the still image to obtain an isolated digital image of the modulated illumination of the scene; and
demodulating the emitted light signal from the isolated digital image.

2. The method of claim 1 , wherein removing the calculated noise comprises subtracting the plurality of pixel values corresponding to the un-modulated illumination of the scene from the plurality of pixel values corresponding to the modulated illumination of the scene.

3. The method of claim 1 , wherein demodulating the emitted light signal from the isolated digital image comprises:
applying a blob detection algorithm to the isolated digital image, wherein a blob represents a region of interest identifiable as one of a plurality of beacon light sources, the blob detection algorithm including:
determining an average pixel value for the region of interest;
comparing the average pixel value to a threshold value; and
based on the comparison, storing a binary value for the region of interest in a processed image indicating where the plurality of beacon light sources are detected.

4. The method of claim 3 , further comprising;
identifying a physical location of the device based on the processed image indicating where the plurality of beacon light sources are detected.

5. The method of claim 4 , wherein the processed image is at a sampling rate equal to a frame rate of the image sensor.

6. The method of claim 1 , wherein removing the calculated noise comprises:
applying phase correlation to detect scene motion between a plurality of frames, the plurality of frames including the still image;
upon detecting the scene motion between the plurality of frames, transforming the plurality of frames by shifting each of the plurality of frames to cause each frame to overlie a previous frame;
generating an averaged image by averaging a plurality of frames such that a banding effect due to the time-varying illumination of a plurality of beacon light sources is reduced to a constant value added on to all pixels of the averaged image; and
subtracting the averaged image from the still image to reveal the isolated digital image that is independent of the scene.

7. The method of claim 1 , wherein calculating the noise comprises averaging the plurality of pixel values of each given point of the still image.

8. The method of claim 7 , wherein the averaging is performed using a technique comprising one of calculating a simple numerical average, calculating a normalized average, calculating a Gaussian average, or calculating a difference between the still image and at least one prior digital image previously received electronically by the image sensor of the device.

9. The method of claim 1 , wherein removing the calculated noise comprises subtracting the calculated noise from the still image to obtain the isolated digital image.

10. The method of claim 9 , wherein demodulating the emitted light signal from the isolated digital image comprises taking the Fourier transform of row values along different columns of the isolated digital image.

11. An apparatus comprising:
an imaging sensor; and
a processor in communication with the imaging sensor configured to:
electronically receive a still image of a scene, wherein:
the scene comprises both modulated illumination emitted by a beacon light source and un-modulated illumination; and
the still image comprises a plurality of pixel values, each of the plurality of pixel values being for a given point in the still image;

calculate noise from the still image, wherein the noise comprises information within the still image corresponding to the un-modulated illumination of the scene;
remove the calculated noise from the still image to obtain an isolated digital image of the modulated illumination of the scene; and
demodulate the emitted light signal from the isolated digital image.

12. The apparatus of claim 11 , wherein the processor is configured to remove the calculated noise using a technique comprising subtracting the plurality of pixel values corresponding to the un-modulated illumination of the scene from the plurality of pixel values corresponding to the modulated illumination of the scene.

13. The apparatus of claim 11 , wherein demodulating the emitted light signal from the isolated digital image comprises:
applying a blob detection algorithm to the isolated digital image, wherein a blob represents a region of interest identifiable as one of a plurality of beacon light sources, the blob detection algorithm including:
determining an average pixel value for the region of interest;
comparing the average pixel value to a threshold value; and
based on the comparison, storing a binary value for the region of interest in a processed image indicating where the plurality of beacon light sources are detected.

14. The apparatus of claim 13 , wherein the processor is configured to identify a physical location of the apparatus based on the processed image indicating where the plurality of beacon light sources are detected.

15. The apparatus of claim 14 , wherein the processed image is at a sampling rate equal to a frame rate of the image sensor.

16. The apparatus of claim 11 , wherein removing the calculated noise comprises:
applying phase correlation to detect scene motion between a plurality of frames, the plurality of frames including the still image;
upon detecting the scene motion between the plurality of frames, transforming the plurality of frames by shifting each of the plurality of frames to cause each frame to overlie a previous frame;
generating an averaged image by averaging a plurality of frames such that a banding effect due to the time-varying illumination of a plurality of beacon light sources is reduced to a constant value added on to all pixels of the averaged image; and
subtracting the averaged image from the still image to reveal the isolated digital image that is independent of the scene.

17. The apparatus of claim 11 , wherein the processor is configured to perform the calculating of noise using a technique comprising averaging the plurality of pixel values of each given point of the still image.

18. The apparatus of claim 17 , wherein the processor is configured to perform averaging using a technique comprising one of calculating a simple numerical average, calculating a normalized average, calculating a Gaussian average, or calculating a difference between the still image and at least one prior digital image previously received electronically by the imaging sensor.

19. The apparatus of claim 11 , wherein removing the calculated noise comprises subtracting the calculated noise from the still image to obtain the isolated digital image.

20. The apparatus of claim 19 , wherein demodulating the emitted light signal from the isolated digital image comprises taking the Fourier transform of row values along different columns of the isolated digital image.

21. A device comprising:
an

Assignees

• Abl Ip Holding Llc
• Abl Ip Holdings Llc

Inventors

• Ryan Daniel
• Staats Peter
• Sumner Jr Robert

Classifications

• H04B10/1149

  Arrangements for indoor wireless networking of information · CPC title

• H04B10/116

  Visible light communication · CPC title

• H04N23/80

  Camera processing pipelines; Components thereof · CPC title

• H04N23/57

  Mechanical or electrical details of cameras or camera modules specially adapted for being embedded in other devices · CPC title

• H04N23/81

  for suppressing or minimising disturbance in the image signal generation · CPC title