Optical flow estimation method
AssigneeQueen Mary & Westfield College, University of London
InventorsMiguel Coimbra, Michael Davies
Life of this patent
Estimating the term…
Abstract
The optical flow in an image is estimated using only parameters extracted directly from a compressed video data stream, substantially eliminating the need to decode the video data stream for this purpose. Coefficients extracted from the compressed video data stream are used to establish a confidence map indicative of the edge strength within the image data and hence the accuracy of the associated motion field. A smooth motion field is generated from the motion vectors inherent in the compressed video data stream. The motion field is then used to update the confidence map between frames, providing an estimate of the optical flow.
Claims23
An optical flow estimation method comprising the steps of:
- (a) obtaining encoded image data representative of an image sequence of a changing object having a motion field;
- (b) extracting from said encoded image data first frame data blocks not incorporating motion vector encoding;
- (c) extracting from said encoded image data second frame data blocks incorporating motion vector encoding;
- (d) determining from said first frame data blocks confidence map data indicative of the edge strength within said encoded image data and hence the accuracy of the motion field;
- (e) deriving from said second frame data blocks smooth motion field data blocks in which each data block has a single motion vector and the magnitudes of the motion vectors are normalised;
- and
- (f) updating the confidence map data on the basis of the smooth motion field data blocks to provide output data indicative of the optical flow of the image.
An optical flow estimation system utilising encoded image data representative of an image sequence of a changing object having a motion field, the system comprising:
- (a) first extraction means for extracting from said encoded image data first frame data blocks not incorporating motion vector encoding;
- (b) second extraction means for extracting from said encoded image data second frame data blocks incorporating motion vector encoding;
- (c) determination means for determining from said first frame data blocks confidence map data indicative of the edge strength within said encoded image data and hence the accuracy of the motion field;
- (d) derivation means for deriving from said second frame data blocks smooth motion field data blocks in which each data block has a single motion vector and the magnitudes of the motion vectors are normalised;
- and
- (e) updating means for updating said confidence map data on the basis of said smooth motion field data blocks to provide output data indicative of the optical flow of the image.
A computer readable recording medium on which is recorded an optical flow estimation program for causing a computer to execute the following steps:
- (a) extracting, from encoded image data representative of an image sequence of a changing object having a motion field, first frame data blocks not incorporating motion vector encoding;
- (b) extracting from said encoded image data second frame data blocks incorporating motion vector encoding;
- (c) determining from said first frame data blocks confidence map data indicative of the edge strength within said encoded image data and hence the accuracy of the motion field;
- (d) deriving from said second frame data blocks smooth motion field data blocks in which each data block has a single motion vector and the magnitudes of the motion vectors are normalised;
- and
- (e) updating the confidence map data on the basis of the smooth motion field data blocks to provide output data indicative of the optical flow of the image.
Dependencies are inferred from the claim text.