Method and apparatus for tracking a moving object
AssigneeU.S. Philips Corporation
InventorsTimothy I. P. Trew, Gabriele C. Seeling
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Abstract
A method of tracking a moving object in a scene, for example the face of a person in videophone applications, comprises forming an initial template of the face, extracting a mask outlining the face, dividing the template into a plurality (for example sixteen) sub-templates, searching the next frame to find a match with the template, searching the next frame to find a match with each of the sub-templates, determining the displacements of each of the sub-templates with respect to the template, using the displacements to determine affine transform coefficients and performing an affine transform to produce an updated template and updated mask.
Claims13
A method of tracking the movement of a three dimensional object in a scene over a series of two dimensional picture frames, the method comprising the steps of
- a) forming an initial template in an initial frame of the series, said initial template including the moving object to be tracked;
- b) dividing said initial template into a plurality of sub-templates which are not associated with specific features of said object;
- c) searching a subsequent frame of said series to locate a first region of said subsequent frame which matches said initial template and determining a first displacement in position between said initial template and said first region of said subsequent frame;
- d) searching said subsequent frame of said series to locate respective sub-regions of said subsequent frame of said series which match respective sub-templates of the initial template and determining respective additional displacements in position between each sub-template and its respective matched sub-region of said subsequent frame;
- e) determining from the first displacement and the additional displacements, a relative displacement in position between said first region of said subsequent frame and said respective sub-regions of said subsequent frame;
- f) using said relative displacement to determine coefficients for a bivariate transform capable of mapping said first and additional displacements in position;
- and
- g) performing said bivariate transform to produce an updated initial template.
An apparatus for tracking the movement of a three dimensional object in a scene over a series of two dimensional picture frames, said apparatus comprising in combination:
- a) means for forming an initial template in an initial frame of the series, said initial template including the moving object to be tracked;
- b) means for dividing said initial template into a plurality of sub-templates which are not associated with specific features of said object;
- c) means for searching a subsequent frame of said series to locate a first region of said subsequent frame which matches said initial template and determining a first displacement in position between said initial template and said first region of said subsequent frame;
- d) means for searching said subsequent frame of said series to locate respective sub-regions of said subsequent frame of said series which match respective sub-templates of the initial template and determining respective additional displacements in position between each sub-template and its respective matched sub-regions of said subsequent frame;
- e) means for determining from the first displacement and the additional displacements, a relative displacement in position between said first region of said subsequent frame and said respective sub-regions of said subsequent frame;
- f) means for determining coefficients for a bivariate transform capable of mapping said first and additional displacements in position using said relative displacement;
- and
- g) means for performing said bivariate transform to produce an updated initial template.
Dependencies are inferred from the claim text.