Abstract: The present invention relates to a method and system for foreground segmentation in which frames of a video sequence are analyzed in the transform domain to determine one or more features. The features are used to model the background. The background can be modeled as a single Gaussian model with a mean and variance of the features. A current frame is segmented by determining if one or more features of the current frame analyzed in the foreground domain satisfy a threshold between the background model. The threshold value can be based on the mean and/or variance of features. During the segmentation, the mean and variance can be updated based on previous corresponding values and current features to adaptively update the background model. In one embodiment, the frames are divided into a plurality of blocks. A transform is used to analyze the blocks in the transform domain. For example, the transform can be a discrete cosine transform (DCT).

Abstract: A model stored in a memory accessible by a video transcoder includes a first rate-distortion function modeling a requantization of an input video. A second-rate distortion function models a resynchronization marker insertion rate for the transcoded video, and a third rate-distortion function models an intra-block insertion rate for the transcoded video.

Abstract: A method and system reduces the spatial resolution of a compressed bitstream of a sequence of frames of a video signal by first decoding the frames, and storing the decoded frames in a first frame buffer. While performing the decoding, motion compensating is performed with full resolution motion vectors of the stored decoded frames. The decoded frames are then down-sampled to a reduced resolution, and stored in a second frame buffer. The reduced resolution frames are partially encoded to produce a reduced resolution compressed bitstream of the video. While performing the partial encoding, motion compensation is performed with reduced resolution motion vectors of the stored reduced resolution frames.

Abstract: A method compensates for drift in macroblocks of a partially decoded input bitstream. The macroblocks include intra-mode and inter-mode macroblocks, and each macroblock includes DCT coefficients, and at least one motion vector. An estimate of drift is measured in the partially decoded input bitstream. The estimated drift is translated into an intra refresh rate. The modes of inter-mode macroblock are mapped to intra-mode macroblock according to the refresh rate. The DCT coefficients and the motion vector for each changed macroblock are modified in accordance with the mapping for each changed macroblock.

Abstract: A method transcodes an input video to an output video, which can have a lower bit rate than the input video. Sets of rate values and corresponding sets of distortion values are determined for each components of the output video. There is one set of rate values and one corresponding set of distortion values for each component in the output video. The components include a requantization of the input video, inserted resynchronization markers, and inserted intra-blocks. Then, bits are allocated to each of the components in the output video according to the associated set of rate values and the associated corresponding set of distortion values.

Abstract: A model stored in a memory accessible by a video transcoder includes a first rate-distortion function modeling a requantization of an input video. A second-rate distortion function models a resynchronization marker insertion rate for the transcoded video, and a third rate-distortion function models an intra-block insertion rate for the transcoded video.

Abstract: The present invention relates to a method and system for foreground segmentation in which frames of a video sequence are analyzed in the transform domain to determine one or more features. The features are used to model the background. The background can be modeled as a single Gaussian model with a mean and variance of the features. A current frame is segmented by determining if one or more features of the current frame analyzed in the foreground domain satisfy a threshold between the background model. The threshold value can be based on the mean and/or variance of features. During the segmentation, the mean and variance can be updated based on previous corresponding values and current features to adaptively update the background model. In one embodiment, the frames are divided into a plurality of blocks. A transform is used to analyze the blocks in the transform domain. For example, the transform can be a discrete cosine transform (DCT).

Abstract: A method transcodes groups of macroblocks of a partially decoded input bitstream. The groups of macroblocks include intra-mode and inter-mode macroblocks. Each macroblock includes DCT coefficients, and at least one motion vector. The modes of each group of macroblocks are mapped to be identical only if there is an inter-mode block and an intra-mode macroblock in the group. If any of the macroblocks in the group are mapped, then the DCT coefficients and the motion vector for such mapped macroblocks are modified in accordance with the mapping to generate reduced-resolution macroblock for an output compressed bitstream to compensate for drift.

Abstract: A method transcodes groups of macroblocks of a partially decoded input bitstream. The groups of macroblocks include intra-mode and inter-mode macroblocks. Each macroblock includes DCT coefficients, and at least one motion vector. The modes of each group of macroblocks are mapped to be identical only if there is an inter-mode block and an intra-mode macroblock in the group. If any of the macroblocks in the group are mapped, then the DCT coefficients and the motion vector for such mapped macroblocks are modified in accordance with the mapping to generate reduced-resolution macroblock for an output compressed bitstream to compensate for drift.

Abstract: A method and system reduces the spatial resolution of a compressed bitstream of a sequence of frames of a video signal by first decoding the frames, and storing the decoded frames in a first frame buffer. While performing the decoding, motion compensating is performed with full resolution motion vectors of the stored decoded frames. The decoded frames are then down-sampled to a reduced resolution, and stored in a second frame buffer. The reduced resolution frames are partially encoded to produce a reduced resolution compressed bitstream of the video. While performing the partial encoding, motion compensation is performed with reduced resolution motion vectors of the stored reduced resolution frames.

Abstract: A method compensates for drift in macroblocks of a partially decoded input bitstream. The macroblocks include intra-mode and inter-mode macroblocks, and each macroblock includes DCT coefficients, and at least one motion vector. An estimate of drift is measured in the partially decoded input bitstream. The estimated drift is translated into an intra refresh rate. The modes of inter-mode macroblock are mapped to inter-mode macroblock according to the refresh rate. The DCT coefficients and the motion vector for each changed macroblock are modified in accordance with the mapping for each changed macroblock.

Abstract: A digital watermarking process whereby an invisible watermark inserted into a host image is utilized to determine whether or not the image has been altered and, if so, where in the image such alteration occurred. The watermarking method includes the steps of providing a look-up table containing a plurality of coefficients and corresponding values; transforming the image into a plurality of blocks, wherein each block contains coefficients matching coefficients in the look-up table; and embedding the watermark in the image by performing the following substeps for at least some of the blocks: First, a coefficient is selected for insertion of a marking value representative of a corresponding portion of the watermark. Next, the value of the selected coefficient to used to identify a corresponding value in the look-up table. Finally, the identified coefficient is left unchanged if the corresponding value is the same as the marking value, and is changed if the corresponding value is different from the marking value.

Abstract: A new technique for extracting a hierarchical decomposition of a complex video selection for browsing purposes, combines visual and temporal information to capture the important relations within a scene and between scenes in a video, thus allowing the analysis of the underlying story structure with no a priori knowledge of the content. A general model of hierarchical scene transition graph is applied to an implementation for browsing. Video shots are first identified and a collection of key frames is used to represent each video segment. These collections are then classified according to gross visual information. A platform is built on which the video is presented as directed graphs to the user, with each category of video shots represented by a node and each edge denoting a temporal relationship between categories. The analysis and processing of video is carried out directly on the compressed videos.

Abstract: A new technique for extracting a hierarchical decomposition of a complex video selection for browsing purposes, combines visual and temporal information to capture the important relations within a scene and between scenes in a video, thus allowing the analysis of the underlying story structure with no a priori knowledge of the content. A general model of hierarchical scene transition graph is applied to an implementation for browsing. Video shots are first identified and a collection of key frames is used to represent each video segment. These collections are then classified according to gross visual information. A platform is built on which the video is presented as directed graphs to the user, with each category of video shots represented by a node and each edge denoting a temporal relationship between categories. The analysis and processing of video is carried out directly on the compressed videos.

Abstract: In an image coding system, block based motion estimation is used to determine motion vectors for blocks of pixels in a current frame or field. Only a portion of blocks from a predetermined pattern of blocks in a current frame or field are searched for a match with a block of pixels in a previous frame or field over a designated search area. Motion vectors for the blocks of the current frame or field not selected for searching are obtained by interpolation from motion vectors obtained for associated searched neighboring blocks, respectively, or by using the zero motion vector, or by performing a search over a limited range around the position defined by each of the motion vectors from neighboring blocks.

Abstract: In an imaging system, block based motion estimation is used to determine motion vectors for blocks of pixels in a current frame or field. Only a portion of blocks from a predetermined pattern of blocks in a current frame or field are searched for a match with a block of pixels in a previous frame or field over a designated search area. Motion vectors for the blocks of the current frame or field not selected for searching are obtained by interpolation from motion vectors obtained for associated searched neighboring blocks, respectively.

Abstract: The detector is responsive to a modulated intermediate frequency (IF) or radio frequency (RF) signal for producing four sample signals spaced at 90.degree. one-quarter IF (or RF) cycle apart, the first and third sample signals corresponding to the amplitude of the IF signal and its negative value, respectively, the stream of such sample signals corresponding to the inphase component of the IF signal; the fourth and second sample signals corresponding to the amplitude of the IF signal and its negative value, respectively, the stream of such sample signals corresponding to the quadrature component of the IF signal.

Abstract: A combinatorial digital filter apparatus utilizing a second order filter in which bits are processed simultaneously rather than serially.