Motion-based segmentor detecting vehicle occupants using optical flow method to remove effects of illumination
First Claim
1. A method for isolating a current segmented image from a current ambient image, comprising the steps of:
- a) computing a directional gradient image for the current ambient image;
b) computing a time difference image, wherein the time difference image comprises a difference between the current ambient image and a prior ambient image;
c) computing an optical flow field image and an illumination field image, responsive to the directional gradient image, the time difference image, and the current ambient image; and
d) performing an adaptive threshold computation on the optical flow field image thereby generating a binary image, wherein the current segmented image corresponds to and is associated with at least part of the binary image.
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Abstract
An image segmentation method and apparatus are described. The inventive system and apparatus generates a segmented image of an occupant or other target of interest based upon an ambient image, which includes the target and the environment in the vehicle that surrounds the target. The inventive concept defines a bounding ellipse for the target. This ellipse may be provided to a processing system that performs tracking of the target. In one embodiment, an optical flow technique is used to compute motion and illumination field values. The explicit computation of the effects of illumination dramatically improves motion estimation and thereby facilitates computation of the bounding ellipses.
66 Citations
19 Claims
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1. A method for isolating a current segmented image from a current ambient image, comprising the steps of:
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a) computing a directional gradient image for the current ambient image;
b) computing a time difference image, wherein the time difference image comprises a difference between the current ambient image and a prior ambient image;
c) computing an optical flow field image and an illumination field image, responsive to the directional gradient image, the time difference image, and the current ambient image; and
d) performing an adaptive threshold computation on the optical flow field image thereby generating a binary image, wherein the current segmented image corresponds to and is associated with at least part of the binary image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A segmentation system for isolating a current segmented image from a current ambient image, comprising:
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a) a camera, wherein the camera outputs a the current ambient image and a prior ambient image, and wherein the current ambient image includes the current segmented image;
b) a directional gradient and time difference module, wherein the directional gradient and time difference module generates a directional gradient image and a time difference image based on the current ambient image and the prior ambient image;
c) an optical flow module, wherein the optical flow module calculates and outputs an optical flow field image and an illumination field image; and
d) an adaptive threshold module, wherein the adaptive threshold module generates a binary image, and wherein the current segmented image corresponds to and is associated with at least part of the binary image. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A segmentation system for isolating a current segmented image from a current ambient image, comprising:
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a) means for computing a directional gradient image for the current ambient image;
b) means for computing a time difference image, wherein the time difference image comprises a difference between the current ambient image and a prior ambient image;
c) means for computing an optical flow field image and an illumination field image, responsive to the directional gradient image, the time difference image, and the current ambient image; and
a) means for performing an adaptive threshold computation on the optical flow field image thereby generating a binary image, wherein the current segmented image corresponds to and is associated with at least part of the binary image.
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19. A computer program, executable on a general purpose computer, comprising:
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a) a first set of instructions for computing a directional gradient image for the current ambient image;
b) a second set of instructions for computing a time difference image, wherein the time difference image comprises a difference between the current ambient image and a prior ambient image;
c) a third set of instructions for computing an optical flow field image and an illumination field image, responsive to the directional gradient image, the time difference image, and the current ambient image; and
d) a fourth set of instructions for performing an adaptive threshold computation on the optical flow field image thereby generating a binary image, wherein the current segmented image corresponds to and is associated with at least part of the binary image.
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Specification