Stereo-image processing apparatus

• US 8,417,022 B2
• Filed: 06/25/2008
• Issued: 04/09/2013
• Est. Priority Date: 06/28/2007
• Status: Active Grant

• Current Assignee: Subaru Corp.
• Original Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Inventors: Morimitsu, Noboru
• Primary Examiner(s): DULANEY, KATHLEEN YUAN
• Application Number:
  US12/213,884
• Publication Number:
  US 20090046924A1
• Time in Patent Office: 1,749 Days
• Field of Search: 382/154, 382/104, 382/278, 382/294, 345/419, 348/116, 348/42, 348/153, 356/12, 356/3.14, 340/939
• US Class Current: 382/154
• CPC Class Codes: G01C 11/06 by comparison of two or more pictures of the same area

Abstract

A stereo-image processing apparatus includes a stereo-image taking means configured to take a plurality of images from different viewpoints, a parallax detecting means configured to detect a parallax of a subject on the basis of the images taken by the stereo-image taking means, an object detecting means configured to detect objects on the basis of the parallax detected by the parallax detecting means and a parallax offset value, and a parallax-offset-value correcting means configured to correct the parallax offset value on the basis of a change in a parallax corresponding to an object whose size in real space does not change with time, of the objects detected by the object detecting means, and a change in an apparent size of the object.

Claims

1. A stereo-image processing apparatus, comprising:

stereo-image taking means configured to take a plurality of images from different viewpoints;

parallax detecting means configured to detect parallax of a subject based on the images taken by the stereo-image taking means;

object detecting means configured to detect objects based on parallax detected by the parallax detecting means and a parallax offset value; and

parallax-offset-value correcting means configured to correct the parallax offset value based on a change in parallax corresponding to an object whose size in real space does not change with time, of the objects detected by the object detecting means, and a change in an apparent size of the object, wherein

the parallax-offset-value correcting means calculates a parallax error based on the changes in parallax and the apparent size of the object, and corrects the parallax offset value based on the parallax error,

the parallax-offset-value correcting means calculates the parallax error ε

according to the following expression when parallax changes from dp₁ to dp₂ and the apparent size of the object changes from b₁ to b₂;

ε

=(b₁·

dp₂−

b₂·

dp₁)/(b₂−

b₁), and

the parallax-offset-value correcting means corrects the parallax offset value based on the parallax error ε

.

2. The stereo-image processing apparatus according to claim 1, wherein the parallax-offset-value correcting means forms a histogram for a plurality of parallax errors calculated at different times, and corrects the parallax offset value based on the mode of the histogram.

4. The stereo-image processing apparatus according to claim 1, wherein

the detected object, which is determined to undergo an apparent change in size, is an object above a road surface.

5. The stereo-image processing apparatus according to claim 4, further comprising:

taillight distance detecting means configured to detect a distance between right and left taillights of a preceding vehicle, wherein

the object detecting means detects a preceding vehicle as the object whose size in real space does not change,

the parallax-offset-value correcting means corrects the parallax offset value based on a change in parallax corresponding to the right and left taillights and a change in an apparent distance in the images between the right and left taillights of the preceding vehicle.

6. The stereo-image processing apparatus according to claim 4, further comprising:

storage means configured to store parallax and the apparent size of the detected object,

wherein, when the detected object is exchanged, a history of the storage means is cleared.

7. The stereo-image processing apparatus according to claim 6, wherein an exchange of the detected object is determined to occur when the object detection means detects that a second object entered into the image field of the stereo-image taking means.

8. The stereo-image processing apparatus according to claim 4, wherein

the stereo-image taking means is configured to take a plurality of images from different viewpoints within an image field,

a determination as to whether the detected object has undergone an apparent change in size is made by a comparing first image data with second image data, and

the detected object is present in the image field during both a first period corresponding to the first image data and a second period corresponding to the second image data.

9. The stereo-image processing apparatus according to claim 1, wherein the object is a preceding vehicle.

3. The stereo-image processing apparatus the apparent size of the object is a width of the object in the images.

10. A stereo-image processing apparatus comprising:

stereo-image taking means configured to take a plurality of images from different viewpoints;

parallax detecting means configured to detect parallax of a subject based on the images taken by the stereo-image taking means;

object detecting means configured to detect objects based on parallax detected by the parallax detecting means and a parallax offset value; and

parallax-offset-value correcting means configured to correct the parallax offset value based on a change in parallax corresponding to an object whose size in real space does not change with time, of the objects detected by the object detecting means, and a change in an apparent size of the object, wherein

the object detecting means detects a preceding vehicle as the object whose size in real space does not change with time, and

the parallax-offset-value correcting means corrects the parallax offset value based on a change in parallax corresponding to the preceding vehicle and a change in an apparent size of the preceding vehicle in the images serving as the apparent size of the object; and

the stereo-image processing apparatus further comprising taillight distance detecting means configured to detect a distance between right and left taillights of the preceding vehicle, wherein

the parallax-offset-value correcting means corrects the parallax offset value based on a change in parallax corresponding to the right and left taillights and a change in an apparent distance in the images between the right and left taillights of the preceding vehicle.

11. The stereo-image processing apparatus according to claim 10, further comprising:

storage means configured to store parallax and the apparent size of the object,

wherein, when the preceding vehicle detected by the object detecting means is exchanged, a history of parallax and the apparent size of the object stored in the storage means is cleared.

12. A stereo-image processing apparatus comprising:

stereo-image taking means configured to take, within an image field, a plurality of images from different viewpoints within the image field;

parallax detecting means configured to detect parallax of a subject based on the images taken by the stereo-image taking means;

object detecting means configured to detect objects based on parallax detected by the parallax detecting means and a parallax offset value; and

parallax-offset-value correcting means configured to correct the parallax offset value based on a change in parallax corresponding to a change in an apparent size of an object detected by the object detecting means, which object does not change in size in real space, wherein

a determination as to whether the detected object has undergone an apparent change in size is made by a comparing first image data with second image data,

the detected object is present in the image field during both a first period corresponding to the first image data and a second period corresponding to the second image data,

the parallax-offset-value correcting means calculates a parallax error ε

according to the following expression when parallax changes from dp₁ to dp₂ and the apparent size of the object changes from b₁ to b₂;

ε

=(b₁·

dp₂−

b₂·

dp₁)/(b₂−

b₁), and

the parallax-offset-value correcting means corrects the parallax offset value based on the parallax error ε

.

13. The stereo-image processing apparatus according to claim 12, further comprising:

taillight distance detecting means configured to detect a distance between right and left taillights of a preceding vehicle, wherein

the object detecting means detects a preceding vehicle as the object whose size in real space does not change,

the parallax-offset-value correcting means corrects the parallax offset value based on a change in parallax corresponding to the right and left taillights and a change in an apparent distance in the images between the right and left taillights of the preceding vehicle.

14. The stereo-image processing apparatus according to claim 12, further comprising:

storage means configured to store parallax and the apparent size of the detected object,

wherein, when the detected object is exchanged, a history of the storage means is cleared.

15. The stereo-image processing apparatus according to claim 14, wherein an exchange of the detected object is determined to occur when the object detection means detects that a second object entered into the image field of the stereo-image taking means.