Method and apparatus for calibrating sampling operations for an object detection process

• US 7,440,587 B1
• Filed: 11/24/2004
• Issued: 10/21/2008
• Est. Priority Date: 11/24/2004
• Status: Active Grant

• Current Assignee: Adobe Inc.
• Original Assignee: Adobe Systems Incorporated (Adobe Inc.)
• Inventors: Bourdev, Lubomir D.
• Primary Examiner(s): Tabatabai; Abolfazl
• Application Number:
  US10/997,395
• Time in Patent Office: 1,427 Days
• Field of Search: 382/103, 382/107, 382/115, 382/116, 382/117, 382/118, 382/227, 382/297, 382/317, 348/77, 348/94, 348/152, 348/154, 348/155, 348/169, 348/170, 348/171, 348/172, 348/208.16, 348/352, 348/353, 348/356
• US Class Current: 382/103
• CPC Class Codes: G06V 10/255 Detecting or recognising potential candidate objects based on visual cues, e.g. shapes
• CPC Class Codes: G06V 10/75 Organisation of the matching processes, e.g. simultaneous or sequential comparisons of image or video features; Coarse-fine approaches, e.g. multi-scale approaches; using context analysis; Selection of dictionaries

Abstract

One embodiment of the present invention provides a system that detects an object in an image. During operation, the system determines a relationship between sampling parameters and a detection rate for an object detection process. The system also determines a relationship between the sampling parameters and a detection speed for the object detection process. The system uses the determined relationships to generate specific sampling parameters. Next, the system performs the object detection process, wherein the object detection process uses the sampling parameters to sample locations in the image. This sampling process is used to refine the search for the object by identifying locations that respond to an object detector and are hence likely to be proximate to an instance of the object.

Claims

1. A method for detecting an object in an image, comprising:

determining a relationship between sampling parameters and a detection rate for an object detection process;

determining a relationship between the sampling parameters and a detection speed for the object detection process;

wherein the sampling parameters include;

a sampling function, which determines locations within the image to sample; and

a refinement threshold, wherein if a response obtained while sampling a given location exceeds the refinement threshold, a localized search for the object is performed in the vicinity of the given location;

using the determined relationships to generate specific sampling parameters; and

performing the object detection process, wherein the object detection process uses the sampling parameters to sample locations in the image, wherein a sampling process is used to refine the search for the object by identifying locations that respond to an object detector and are hence likely to be proximate to an instance of the object.

2. The method of claim 1, wherein generating the specific sampling parameters involves balancing detection speed and detection rate.

3. The method of claim 2, wherein generating the specific sampling parameters involves maximizing detection speed for a fixed detection rate.

4. The method of claim 2, wherein generating the specific sampling parameters involves maximizing detection rate for a fixed detection speed.

5. The method of claim 1, wherein the object detection process involves:

using the sampling function to identify locations in the image to sample; and

applying the object detector to the identified locations;

wherein if the object detector'"'"'s response at a given location exceeds the refinement threshold, the method further comprises refining the search by attempting to locate a perfect center for the object in the vicinity of the given location.

6. The method of claim 1, wherein the sampling function is determined based upon empirical results obtained while using the object detector.

7. The method of claim 1, wherein the refinement threshold is determined based upon empirical results obtained while using the object detector.

8. A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for detecting an object in an image, the method comprising:

determining a relationship between sampling parameters and a detection rate for an object detection process;

determining a relationship between the sampling parameters and a detection speed for the object detection process;

wherein the sampling parameters include;

a sampling function which determines locations within the image to sample; and

a refinement threshold wherein if a response obtained while sampling a given location exceeds the refinement threshold a localized search for the object is performed in the vicinity of the given location;

using the determined relationships to generate specific sampling parameters; and

performing the object detection process, wherein the object detection process uses the sampling parameters to sample locations in the image, wherein a sampling process is used to refine the search for the object by identifying locations that respond to an object detector and are hence likely to be proximate to an instance of the object.

9. The computer-readable storage medium of claim 8, wherein generating the specific sampling parameters involves balancing detection speed and detection rate.

10. The computer-readable storage medium of claim 9, wherein generating the specific sampling parameters involves maximizing detection speed for a fixed detection rate.

11. The computer-readable storage medium of claim 9, wherein generating the specific sampling parameters involves maximizing detection rate for a fixed detection speed.

12. The computer-readable storage medium of claim 8, wherein the object detection process involves:

using the sampling function to identify locations in the image to sample; and

applying the object detector to the identified locations;

wherein if the object detector'"'"'s response at a given location exceeds the refinement threshold, the method further comprises refining the search by attempting to locate a perfect center for the object in the vicinity of the given location.

13. The computer-readable storage medium of claim 8, wherein the sampling function is determined based upon empirical results obtained while using the object detector.

14. The computer-readable storage medium of claim 8, wherein the refinement threshold is determined based upon empirical results obtained while using the object detector.

15. An apparatus that detects an object in an image, comprising:

a determination mechanism configured to,

determine a relationship between sampling parameters and a detection rate for an object detection process,

and to determine a relationship between the sampling parameters and a detection speed for the object detection process;

wherein the sampling parameters include;

a sampling function, which determines locations within the image to sample; and

a refinement threshold, wherein if a response obtained while sampling a given location exceeds the refinement threshold, the object detection mechanism is configured to perform a localized search for the object in the vicinity of the given location;

a parameter generation mechanism configured to use the determined relationships to generate specific sampling parameters; and

an object detection mechanism configured to perform the object detection process, wherein the object detection process uses the sampling parameters to sample locations in the image, wherein a sampling process is used to refine the search for the object by identifying locations that respond to an object detector and are hence likely to be proximate to an instance of the object.

16. The apparatus of claim 15, wherein while generating the specific sampling parameters, the parameter generation mechanism is configured to balance detection speed and detection rate.

17. The apparatus of claim 16, wherein the parameter generation mechanism is configured to maximize detection speed for a fixed detection rate.

18. The apparatus of claim 16, wherein the parameter generation mechanism is configured to maximize detection rate for a fixed detection speed.

19. The apparatus of claim 15, wherein the object detection mechanism is configured to,

use the sampling function to identify locations in the image to sample, and to

apply the object detector to the identified locations;

and

wherein if the object detector'"'"'s response at a given location exceeds the refinement threshold, the object detection mechanism is configured to refine the search by attempting to locate a perfect center for the object in the vicinity of the given location.

20. The apparatus of claim 15, wherein the sampling function is determined based upon empirical results obtained while using the object detector.

21. The apparatus of claim 15, wherein the refinement threshold is determined based upon empirical results obtained while using the object detector.