Structured Light Depth Imaging Under Various Lighting Conditions

• US 20150003684A1
• Filed: 06/04/2014
• Published: 01/01/2015
• Est. Priority Date: 06/28/2013
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Appia, Vikram VijayanBabu
• Granted Patent: US 10,089,739 B2
• Time in Patent Office: Days
• US Class Current: 382/106
• CPC Class Codes: G01C 11/025 by scanning the object
• CPC Class Codes: G06T 2207/20012 Locally adaptive
• CPC Class Codes: G06T 7/11 Region-based segmentation
• CPC Class Codes: G06T 7/136 involving thresholding
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light
• CPC Class Codes: G06V 20/64 Three-dimensional objects

Abstract

A method of image processing in a structured light imaging system is provided that includes receiving a captured image of a scene, wherein the captured image is captured by a camera of a projector-camera pair, and wherein the captured image includes a binary pattern projected into the scene by the projector, applying a filter to the rectified captured image to generate a local threshold image, wherein the local threshold image includes a local threshold value for each pixel in the rectified captured image, and extracting a binary image from the rectified captured image wherein a value of each location in the binary image is determined based on a comparison of a value of a pixel in a corresponding location in the rectified captured image to a local threshold value in a corresponding location in the local threshold image.

Claims

1. A method of image processing in a structured light imaging system, the method comprising:

receiving a captured image of a scene, wherein the captured image is captured by a camera of a projector-camera pair comprised in the structured light imaging system, and wherein the captured image comprises a binary pattern projected into the scene by the projector;

rectifying the captured image to generated a rectified captured image;

applying a filter to the rectified captured image to generate a local threshold image, wherein the local threshold image comprises a local threshold value for each pixel in the rectified captured image; and

extracting a binary image from the rectified captured image wherein a value of each location in the binary image is determined based on a comparison of a value of a pixel in a corresponding location in the rectified captured image to a local threshold value in a corresponding location in the local threshold image.

2. The method of claim 1, wherein extracting a binary image comprises setting a location in the binary image to one when a value of a pixel in a corresponding location in the rectified captured image is greater than a local threshold value in a corresponding location in the local threshold image and setting the value of the location in the binary image to zero when the value of the pixel is less than the local threshold value.

3. The method of claim 1, wherein the filter generates each local threshold value as a local mean of a corresponding pixel in the rectified image.

4. The method of claim 1, wherein the filter is one selected from a group consisting of a local circular averaging filter and a local box average filter.

5. A structured light imaging system comprising:

an imaging sensor component configured to capture images of a scene;

a projector component configured to project a binary pattern into the scene;

means for rectifying a captured image to generated a rectified captured image;

means for applying a filter to the rectified captured image to generate a local threshold image, wherein the local threshold image comprises a local threshold value for each pixel in the rectified captured image; and

means for extracting a binary image from the rectified captured image wherein a value of each location in the binary image is determined based on a comparison of a value of pixel in a corresponding location in the rectified captured image to a local threshold value in a corresponding location in the local threshold image.

6. The structured light imaging system of claim 5, wherein extracting a binary image comprises setting a location in the binary image to one when a value of a pixel in a corresponding location in the rectified captured image is greater than a local threshold value in a corresponding location in the local threshold image and setting the value of the location in the binary image to zero when the value of the pixel is less than the local threshold value.

7. The structured light imaging system of claim 5, wherein the filter generates each local threshold value as a local mean of a corresponding pixel in the rectified image.

8. The structured light imaging system of claim 5, wherein the filter is one selected from a group consisting of a local circular averaging filter and a local box average filter.

9. A non-transitory computer-readable medium storing instructions that, when executed by at least one processor in a structured light imaging system, cause a method of image processing to be performed, the method comprising:

receiving a captured image of a scene, wherein the captured image is captured by a camera of a projector-camera pair comprised in the structured light imaging system, and wherein the captured image comprises a binary pattern projected into the scene by the projector;

rectifying the captured image to generated a rectified captured image;

applying a filter to the rectified captured image to generate a local threshold image, wherein the local threshold image comprises a local threshold value for each pixel in the rectified captured image; and

extracting a binary image from the rectified captured image wherein a value of each location in the binary image is determined based on a comparison of a value of pixel in a corresponding location in the rectified captured image to a local threshold value in a corresponding location in the local threshold image.

10. The computer-readable medium of claim 9, wherein extracting a binary image comprises setting a location in the binary image to one when a value of a pixel in a corresponding location in the rectified captured image is greater than a local threshold value in a corresponding location in the local threshold image and setting the value of the location in the binary image to zero when the value of the pixel is less than the local threshold value.

11. The computer-readable medium of claim 9, wherein the filter generates each local threshold value as a local mean of a corresponding pixel in the rectified image.

12. The computer-readable medium of claim 9, wherein the filter is one selected from a group consisting of a local circular averaging filter and a local box average filter.