Method and apparatus for detecting motion vectors based on hierarchical motion estimation
First Claim
1. A method for encoding a video signal having a current frame and a preceding frame based on motion vectors between the current and the preceding frames estimated within a frame duration, wherein the current frame is divided into a plurality of search blocks of an identical size and the preceding frame is divided into a corresponding number of search regions, each search region being further divided into a multiplicity of candidate blocks of said identical size, which comprises the steps of:
- (a) grouping the candidate blocks for each search region into a multiple number of search areas of different hierarchies from a highest hierarchy to a lowest hierarchy, each hierarchy having a different threshold value, wherein the search area of the highest hierarchy includes a smaller number of candidate blocks than that of the lowest hierarchy;
(b) motion-estimating each of the search blocks corresponding to each search area starting from the highest hierarchy to the lowest hierarchy to provide a estimated motion vector for each of the search blocks, wherein the motion vector represents the displacement between each of the search blocks and a candidate block which yields a minimum error function smaller than a threshold value of a hierarchy containing the candidate block; and
(c) providing the estimated motion vectors obtained from the step (b) as the motion vectors of the current frame.
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Abstract
Motion vectors are determined between a current frame and a preceding frame within a frame duration by employing a time-sharing multi-tier hierarchical motion estimation approach, wherein the candidate blocks being grouped into a multiple number of hierarchical search areas. The motion vector determination scheme is initiated by performing a motion estimation of a highest hierarchy for all of the search blocks; and an error function and a motion vector of the highest hierarchy are stored. Subsequently, motion-estimation of a lower hierarchy is performed for each of the selected search blocks which have the error functions greater than the threshold value of the highest hierarchy. In the next step, the error functions of the highest and the lower hierarchies are compared for each of the selected search blocks and a smaller error function is selected therefrom to thereby update each of the stored potential motion vectors with the motion vector corresponding to the selected error function. The updating process is repeated for the next hierarchies and the stored potential motion vectors are provided as the motion vectors of the current frame when updating process for the stored potential motion vector for a predetermined lowest hierarchy is accomplished or the frame duration is exhausted.
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Citations
15 Claims
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1. A method for encoding a video signal having a current frame and a preceding frame based on motion vectors between the current and the preceding frames estimated within a frame duration, wherein the current frame is divided into a plurality of search blocks of an identical size and the preceding frame is divided into a corresponding number of search regions, each search region being further divided into a multiplicity of candidate blocks of said identical size, which comprises the steps of:
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(a) grouping the candidate blocks for each search region into a multiple number of search areas of different hierarchies from a highest hierarchy to a lowest hierarchy, each hierarchy having a different threshold value, wherein the search area of the highest hierarchy includes a smaller number of candidate blocks than that of the lowest hierarchy; (b) motion-estimating each of the search blocks corresponding to each search area starting from the highest hierarchy to the lowest hierarchy to provide a estimated motion vector for each of the search blocks, wherein the motion vector represents the displacement between each of the search blocks and a candidate block which yields a minimum error function smaller than a threshold value of a hierarchy containing the candidate block; and (c) providing the estimated motion vectors obtained from the step (b) as the motion vectors of the current frame. - View Dependent Claims (2, 3, 4)
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5. An apparatus for estimating motion vectors between a current frame and a preceding frame within a frame duration, wherein the current frame is divided into a plurality of search blocks of an identical size and the preceding frame is divided into a corresponding number of search regions, each search region being further divided into a multiplicity of candidate blocks of said identical size, which comprises:
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means for grouping the candidate blocks for each search region into a multiple number of search areas of different hierarchies from a highest hierarchy to a lowest hierarchy, each hierarchy having a different threshold value, wherein the search area of the highest hierarchy includes a smaller number of candidate blocks than that of the lowest hierarchy; estimation means for motion-estimating each of the search blocks corresponding to each search area starting from the highest hierarchy to the lowest hierarchy to provide a potential motion vector for each of the search blocks, wherein the motion vector represents the displacement between each of the search blocks and a candidate block which yields a minimum error function smaller than a threshold value of a hierarchy containing the candidate block; and means for providing the potential motion vectors as the motion vectors of the current frame. - View Dependent Claims (6, 7, 8)
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9. An apparatus for encoding a video signal having a current frame and a preceding frame based on motion vectors between the current and the preceding frames estimated within a frame duration, wherein the current frame is divided into a plurality of search blocks of an identical size and the preceding frame is divided into a corresponding number of search regions, each search region being further divided into a multiplicity of candidate blocks of said identical size, which comprises:
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means for grouping the candidate blocks for each search region into a multiple number of search areas of different hierarchies from a highest hierarchy to a lowest hierarchy, each hierarchy having a different threshold value, wherein the search area of the highest hierarchy includes a smaller number of candidate blocks than that of the lowest hierarchy; estimation means for motion-estimating each of the search blocks corresponding to each search area starting from the highest hierarchy to the lowest hierarchy to provide a potential motion vector for each of the search blocks, wherein the motion vector represents the displacement between each of the search blocks and a candidate block which yields a minimum error function smaller than a threshold value of a hierarchy containing the candidate block; and means for providing the potential motion vectors as the motion vectors of the current frame. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification