System and method of auto-exposure control for image acquisition hardware using three dimensional information

• US 8,326,084 B1
• Filed: 12/21/2004
• Issued: 12/04/2012
• Est. Priority Date: 11/05/2003
• Status: Active Grant

• Current Assignee: Cognex Technology & Investment Corporation (Cognex Corporation)
• Original Assignee: Cognex Technology & Investment Corporation (Cognex Corporation)
• Inventors: Marrion, Cyril C. Jr., Nichani, Sanjay
• Primary Examiner(s): Bali, Vikkram
• Application Number:
  US11/019,931
• Time in Patent Office: 2,905 Days
• Field of Search: 382/103, 382/106, 382/154, 382/274, 348/47, 348/143, 348/156, 348/207.1, 348/207.11, 348/208.12, 348/208.14
• US Class Current: 382/285
• CPC Class Codes: G06T 2207/30201 Face
• CPC Class Codes: G06T 7/248 involving reference images or patches
• CPC Class Codes: G06T 7/285 using a sequence of stereo image pairs
• CPC Class Codes: G06T 7/593 from stereo images
• CPC Class Codes: G06V 20/53 Recognition of crowd images, e.g. recognition of crowd congestion
• CPC Class Codes: G07C 9/00 Individual registration on entry or exit
• CPC Class Codes: G07C 9/15 with arrangements to prevent the passage of more than one individual at a time
• CPC Class Codes: H04N 13/296 Synchronisation thereof; Control thereof
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation

Abstract

A system and method of auto-exposure control is provided for image acquisition hardware using three dimensional information to identify a region(s) of interest within an acquired 2D image or images upon which to apply traditional auto-exposure techniques. By performing auto-exposure analysis over the region of interest, the acquisition property settings can be assigned such that the light levels within the region of interest fall within the linear range, producing sufficient grayscale information for identifying particular objects and profiles in subsequently acquired images. For example, in a machine vision application that detects people passing through a doorway, the region of interest can be the portion of the 2D image that generated 3D features of a head and shoulders profile within a 3D model of the doorway scene. With higher quality images, more accurate detection of people candidates within the monitored scene results.

Claims

1. A method of auto-exposure control for image acquisition hardware using three dimensional information, comprising:

acquiring 2D images of a scene from one or more cameras having an initial image acquisition property setting;

detecting 3D features of an object of interest from the 2D images;

defining a region of interest from the 3D features, the region of interest encompassing the entire 3D features and a portion of the 2D images, the portion being adjacent to the 3D features and encompassing the entire border of the 3D features, the region of interest excluding a remainder portion of the images;

analyzing intensity levels in the region of interest to determine a camera acquisition property setting specific to the region of interest;

applying the determined acquisition property setting to the one or more cameras; and

repeating the steps of defining, analyzing and applying as the 3D features are tracked across the 2D images.

2. The method of claim 1 wherein the region of interest includes 3D features that correspond to a head and shoulders profile.

3. The method of claim 1 wherein the initial acquisition property setting and the next acquisition property setting is one or more of a gain control setting, an exposure time setting, an offset setting, a contrast setting, a brightness setting, an illumination setting, a strobe light setting, or a structured lighting setting.

4. The method of claim 1 wherein the one or more cameras is a stereo camera.

5. The method of claim 1 wherein the region of interest includes 3D features that correspond to a profile of a human or other vertebrate body part.

7. The method of claim 5 wherein the portal is a revolving door, a sliding door, a swinging door, or a man trap.

6. A method of auto-exposure control for image acquisition hardware using three dimensional information, comprising:

acquiring 2D images of a scene about a portal from one or more cameras having an initial acquisition property setting;

detecting 3D features of an object of interest from the 2D images;

defining a region of interest from the 3D features, the region of interest encompassing the entire 3D features and a portion of the 2D images, the portion being adjacent to the 3D features and encompassing the entire border of the 3D features, the region of interest excluding a remainder portion of the images;

analyzing intensity levels in the region of interest to determine a camera acquisition property setting specific to the region of interest;

applying the determined acquisition property setting to the one or more cameras; and

repeating the steps of defining, analyzing and applying as the 3D features are tracked across the 2D images.

8. The method of claim 6 wherein the one or more cameras is a stereo camera.

9. The method of claim 6 wherein the region of interest includes 3D features that correspond to a profile of a human or other vertebrate body part.

10. A system of auto-exposure control for image acquisition hardware using three dimensional information, comprising:

one or more cameras having an initial acquisition property setting, the one or more cameras acquiring 2D images of a scene; and

a 3D imaging system detecting 3D features of an object of interest from the 2D images and defining a region of interest from the 3D features, the region of interest encompassing the entire 3D features and a portion of the 2D images, the portion being adjacent to the 3D features and encompassing the entire border of the 3D features, the region of interest excluding a remainder portion of the images, the 3D imaging system analyzing the region of interest to determine a camera acquisition property setting specific to the region of interest and applying the determined acquisition property setting to the one or more cameras.

11. The system of claim 10 wherein:

the 3D imaging system adjusts the location of the region of interest and acquisition property setting as the 3D features are tracked across further 2D images.

12. The system of claim 10 wherein the region of interest includes 3D features that correspond to a head and shoulders profile.

13. The system of claim 10 wherein the initial acquisition property setting and the next acquisition property setting is one or more of a gain control setting, an exposure time setting, an offset setting, a contrast setting, a brightness setting, an illumination setting, a strobe light setting, or a structured lighting setting.

14. The system of claim 10 wherein the one or more cameras is a stereo camera.

15. The system of claim 10 wherein the region of interest includes 3D features that correspond to a profile of a human or other vertebrate body part.

16. A system of auto-exposure control for image acquisition hardware using three dimensional information, comprising:

one or more cameras having an initial acquisition property setting, the one or more cameras acquiring 2D images of a scene about a portal; and

a 3D imaging system detecting 3D features of an object of interest from the 2D images and defining a region of interest from the 3D features, the region of interest including the entire 3D features that correspond to a head and shoulders profile and a portion of the 2D images, the portion being adjacent to the 3D features and encompassing the entire border of the 3D features, the region of interest excluding a remainder portion of the images, the 3D imaging system analyzing the region of interest to determine a camera acquisition property setting specific to the region of interest and applying the determined acquisition property setting to the one or more cameras.

17. The system of claim 16 wherein:

the 3D imaging system adjusts the location of the region of interest and acquisition property setting as the head and shoulders profile is tracked across further 2D images.

18. The system of claim 16 wherein the portal is a revolving door, a sliding door, a swinging door, or a man trap.

19. The system of claim 16 wherein the one or more cameras is a stereo camera.

20. The system of claim 16 wherein the region of interest includes 3D features that correspond to a profile of a human or other vertebrate body part.

21. A system of auto-exposure control for image acquisition hardware using three dimensional information, comprising:

one or more cameras having an initial acquisition property setting, the one or more cameras acquiring 2D images of a scene;

means for detecting 3D features of an object of interest from the 2D images and locating a region of interest from the 3D features, the region of interest encompassing the entire 3D features and a portion of the 2D images, the portion being adjacent to the 3D features and encompassing the entire border of the 3D features and excluding a remainder portion of the images;

means for analyzing intensity levels in the region of interest to determine a camera acquisition property setting specific to the region of interest;

means for applying the determined acquisition property setting to the one or more cameras; and

means for repeating the steps of defining, analyzing and applying as the 3D features are tracked across the 2D images.

22. The system of claim 21 wherein the one or more cameras is a stereo camera.

23. The system of claim 21 wherein the region of interest includes 3D features that correspond to a profile of a human or other vertebrate body part.