Method and apparatus for computing a parallax

• US 9,324,147 B2
• Filed: 07/21/2011
• Issued: 04/26/2016
• Est. Priority Date: 01/22/2009
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Lin, Sixin, Yuan, Hui, Chang, Yilin, Yang, Haitao, Liu, Xiaoxian, Huo, Junyan, Yang, Fuzheng
• Primary Examiner(s): BAILEY, FREDERICK D
• Application Number:
  US13/188,322
• Publication Number:
  US 20110273537A1
• Time in Patent Office: 1,741 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06T 7/55 from multiple images
• CPC Class Codes: G06T 7/97 Determining parameters from multiple pictures depth or shape recovery from multiple images G06T7/55; stereo camera calibration G06T7/85

Abstract

A method and an apparatus for computing a parallax are provided. The method includes: obtaining a plurality of views of a pixel point; computing gradients in a plurality of directions of the pixel point in the plurality of view; computing a matching error corresponding to a parallax of the pixel point according to the gradients; and computing the parallax of the current pixel point according to the matching error. Through the method and the apparatus for computing a parallax, the accuracy of parallax estimation is increased.

Claims

1. A method for electronically computing a parallax, the method comprising:

obtaining a plurality of views of a pixel point, wherein the plurality of views comprises a current view where the pixel point is located and a reference view of a reference pixel point corresponding to the pixel point;

computing gradients in a plurality of directions of the pixel point in the plurality of views;

computing a matching error of the pixel point in the plurality of views;

modifying the matching error according to an average value of absolute differences between gradients of the pixel point and gradients in a plurality of directions of a matching pixel in the reference view; and

computing a parallax of the pixel point according to the modified matching error.

2. The method according to claim 1, wherein each gradient is a luminance difference or a color difference between the pixel point and an adjacent pixel point of the pixel point.

3. The method according to claim 1, wherein computing the gradients in the plurality of directions of the pixel point in the plurality of views comprises:

computing gradients in eight directions of the pixel point in the plurality of views.

4. The method according to claim 1, wherein computing the matching error of the pixel point comprises:

computing the matching error of the pixel point in the current view relative to the reference pixel point in the reference view according to the gradients.

5. The method according to claim 1, wherein after computing the gradients in the plurality of directions of the pixel point in the plurality of views, the method comprises:

performing motion detection on the pixel point in the current view, so as to acquire a detection result; and

computing the matching error of the pixel point comprises;

computing the matching error of the pixel point by referring to the detection result.

6. The method according to claim 5, wherein performing the motion detection on the pixel point in the current view comprises:

computing a difference between an average value of luminances of all pixel points in a window N*N, Nε

{1, 3, 5, 7, . . . } with the pixel point as a center, and an average value of luminances of pixel points of the same position area in an adjacent frame with respect to time;

if the difference is greater than a predetermined motion detection threshold, judging that the pixel point is a motion pixel point; and

if the difference is not greater than a predetermined motion detection threshold, judging that the pixel point is a stationary pixel point.

7. A method for electronically computing a parallax, the method comprising:

obtaining a plurality of views of a pixel point, wherein the plurality of views comprises a current view where the pixel point is located and a reference view of a reference pixel point corresponding to the pixel point;

performing motion detection on the pixel point in the current view and creating a motion detection result;

computing a matching error of the pixel point according to the motion detection result;

computing gradients in a plurality of directions of the pixel point in the plurality of views;

modifying the matching error according to an average value of absolute differences between gradients of the pixel point and gradients in a plurality of directions of a matching pixel in the reference view; and

computing a parallax of the pixel point according to the modified matching error.

8. The method according to claim 7, wherein performing the motion detection on the pixel point in the current view comprises:

computing a difference between an average value of luminances of all pixel points in a window N*N, Nε

{1, 3, 5, 7, . . . } with the pixel point as a center, and an average value of luminances of pixel points of the same position area in an adjacent frame with respect to time;

if the difference is greater than a predetermined motion detection threshold, judging that the pixel point is a motion pixel point; and

if the difference is not greater than a predetermined motion detection threshold, judging that the pixel point is a stationary pixel point.

9. The method according to claim 7, wherein before performing the motion detection on the pixel point in the current view, the method further comprises:

computing the matching error of the pixel point if the pixel point is a first frame in a group of pictures (GOP), or performing the motion detection on the pixel point if the pixel point is not a first frame in a GOP.

10. An apparatus for computing a parallax, the apparatus comprising:

circuitry configured to obtain a plurality of views of a pixel point, wherein the plurality of views comprises a current view where the pixel point is located and a reference view of a reference pixel point corresponding to the pixel point;

circuitry configured to compute gradients in a plurality of directions of the pixel point in the plurality of views;

circuitry configured to compute a matching error of the pixel point and a modified matching error according to an average value of absolute differences between gradients of the pixel point and gradients in a plurality of directions of a matching pixel in the reference view; and

circuitry configured to compute a parallax of the pixel point according to the modified matching error.

11. The apparatus according to claim 10, wherein the apparatus further comprises:

circuitry configured to perform motion detection on the pixel point in the current view and provide a detection result; and

circuitry configured to compute the matching according to the gradients by referring to the detection result.

12. An apparatus for computing a parallax, the apparatus comprising:

circuitry configured to obtain a plurality of views of a pixel point, wherein the plurality of views comprises a current view where the pixel point is located and a reference view of a reference pixel point corresponding to the pixel point;

circuitry configured to compute gradients in a plurality of directions of the pixel point in the plurality of views;

circuitry configured to perform motion detection on the pixel point in the current view and create a motion detection result;

circuitry configured to compute a matching error according to the motion detection result, and configured to modify the matching error according to an average value of absolute differences between gradients of the pixel point and gradients in a plurality of directions of a matching pixel in the reference view; and

circuitry configured to compute a parallax of the pixel point according to the modified matching error.

13. The apparatus according to claim 12, comprising:

circuitry configured to judge whether the pixel point in the current view is a first frame in a GOP, wherein;

if the pixel point is a first frame in a GOP, the circuitry computes the matching error of the pixel point;

if the pixel point is not a first frame in a GOP, the circuitry performs the motion detection on the pixel point.

14. The apparatus according to claim 12, wherein the motion detection comprises:

computing a difference between an average value of luminances of all pixel points in a window N*N, Nε

{1, 3, 5, 7, . . . } with the pixel point as a center, and an average value of luminances of pixel points of the same position area of an adjacent frame with respect to time;

if the difference is greater than a predetermined motion detection threshold, judging that the pixel point is a motion pixel point; and

if the difference is not greater than a predetermined motion detection threshold, judging that the pixel point is a stationary pixel point.