Device, method and digital video encoder for block-matching motion estimation
AssigneeThe Hong Kong University of Science and Technology
InventorsOscar Chi-Lim Au, Ming Lei Liou, Alexandros Tourapis, Guobin Shen
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Abstract
A device or method for video compression uses a technique in which changes in the image are encoded by motions of block of the image and signals indicating evolutions in the block. To determine the motions of the blocks of a each frame, a search is performed for a similar block of a previous frame based on points of the previous frame which are arranged in successive diamond shaped zones. The diamond shaped zones may be centred on the position of the block in previous frame, or one or more predicted motions of the block. The method terminates according to criteria defined using thresholds.
Claims15
A method of selecting, for a first block of a first image based on an array of pixels, a similar block of a second image based on said array of pixels, the method including:
- (i) defining a reference pixel in said array;
- (ii) deriving at least one threshold value based on a previously-derived mismatch value for at least one further block of the first image;
- (iii) defining a plurality of search zones in said array, labelled by integer index i, said zones surrounding said reference pixel and having a radius which increases for increasing i;
- (iv) after step (ii), for successive zones, and for successive pixels in each zone, determining a block of the second image based on each successive pixel of said successive pixels, and determining a mismatch value between said first block of the first image and said determined block based on a mismatch criterion;
- and
- (v) selecting said similar block of the second image as the determined block for which said determined mismatch is lowest;
- wherein step (iv) is terminated upon at least one termination criterion being satisfied, said termination criterion being defined in terms of a respective said threshold value based on a previously-derived mismatch value.
A method of selecting, for a first block of a first image based on an array of pixels, a similar block of a second image based on said array of pixels, the method including:
- (i) defining a reference pixel in said array;
- (ii) deriving at least one threshold value based on a mismatch value of a second block of the first image adjacent said first block;
- (iii) defining a plurality of search zones in said array, labelled by integer index i, said zones surrounding said reference pixel and having a radius which increases for increasing i;
- (iv) after step (ii), for successive zones, and for successive pixels in each zone, determining a block of the second image based on each successive pixel of said successive pixels, and determining a mismatch value between said first block of the first image and said determined block based on a mismatch criterion;
- and
- (v) selecting said similar block of the second image as the determined block for which said determined mismatch is lowest;
- wherein step (iv) is terminated upon at least one termination criterion being satisfied, said termination criterion being defined in terms of a respective said threshold value based on a previously-derived mismatch value.
A method of selecting, for a first block of a first image based on an array of pixels, a similar block of a second image based on said array of pixels, the method including:
- (i) defining a reference pixel in said array;
- (ii) deriving at least one threshold value based on a mismatch value of a second block of the first image adjacent said first block and deriving at least one further threshold value using a previously-derived mismatch value of a block of a third image corresponding in position to said first block of the first image;
- (iii) defining a plurality of search zones in said array, labeled by integer index i, said zones surrounding said reference pixel and having a radius which increases for increasing i;
- (iv) after step (ii), for successive zones, and for successive pixels in each zone, determining a block of the second image based on each successive pixel of said successive pixels, and determining a mismatch value between said first block of the first image and said determined block based on a mismatch criterion;
- and
- (v) selecting said similar block of the second image as the determined block for which said determined mismatch is lowest;
- wherein step (iv) is terminated upon any of a plurality of one termination criterion being satisfied, at least one said termination criterion being defined in terms of a respective said threshold value and at least one said termination criterion being defined in terms of a respective said further threshold value.
Dependencies are inferred from the claim text.