1
Hamid Gharavi: Method and apparatus for low bit-rate interframe video coding. Bell Communications Research, James W Falk, Stephen M Gurey, April 11, 1989: US04821119 (166 worldwide citation)

An improved low bit-rate interframe video encoder is disclosed of the type known as a hybrid coder. A hybrid coder achieves image compression by using a two-dimensional signal transformation on blocks of differential pel data in the forward loop of a DPCM coder. The transform coefficients of each bl ...


2
Hamid Gharavi: Efficient coding scheme for multilevel video transmission. Bell Communications Research, Leonard Charles Suchyta, Stephen M Gurey, October 12, 1993: US05253058 (137 worldwide citation)

A highly efficient video coding scheme is disclosed which codes, for transmission, the pel values of a scanned high quality HDTV video signal in such a manner that a low-quality version of the signal as well as a high-quality version are available to different video subscribers. The coder includes a ...


3
Hamid Gharavi: Apparatus and method for differential sub-band coding of video signals. Bell Communications Research, James W Falk, Stephen M Gurey, November 6, 1990: US04969040 (99 worldwide citation)

A method and apparatus for achieving a high compression of a video signal. The PEL-by-PEL difference between an input signal consisting of digital PEL values of a scanned video signal and a motion compensated interframe prediction signal is decomposed into several narrow bands using separable two-di ...


4
Hamid Gharavi: Two-dimensional block scanning for subband image and video coding. Bell Communications Research, Leonard Charles Suchyta, Stephen M Gurey, January 4, 1994: US05276525 (83 worldwide citation)

A signal coder is disclosed with improved compression of pictorial data that has been decomposed into plural subbands through a two-dimensional quadrature-mirror decomposition (102). In each of the higher frequency bands, the decomposed samples are quantized and then partitioned (106, 110, 114), in ...


5
Hamid Gharavi: Block-matching motion estimator for video coder. Bell Communications Research, Leonard Charles Suchyta, Stephen M Gurey, April 6, 1993: US05200820 (83 worldwide citation)

A method and apparatus (110) for performing block-matching motion estimation in a video coder is disclosed which estimates the motion vector associated with each block of pels in the current coding frame. The motion vector for each block in the current frame is estimated by searching through a large ...


6
Hamid Gharavi: Multilayer universal video coder. Bell Communications Research, Leonard Charles Suchyta, Stephen M Gurey, August 10, 1993: US05235420 (57 worldwide citation)

A video coder is disclosed which codes the digital pel values of a video signal in such a manner that different levels of picture quality, i.e. resolution, are available to users. The coder uses a two-dimensional quadrature-mirror filter (103) to decomposes the input into plural subbands. The baseba ...


7
Hamid Gharavi: Image coding technique. AT&T Bell Laboratories, Ronald D Slusky, March 25, 1986: US04578704 (23 worldwide citation)

In a first embodiment, an image signal is segmented into bilevel and multilevel regions. The picture elements, or pels, representing the bilevel regions are center-thresholded and encoded using a two-dimensional CCITT coding scheme. The pels representing the multilevel regions are coded in a differe ...


8
Hamid Gharavi: Conditional quantization grey level and color image coding apparatus. Bell Communications Research, James W Falk, Stephen M Gurey, September 23, 1986: US04613948 (14 worldwide citation)

In the transmission of PCM coded picture elements (pels), the level value of each pel of an image is quantized in accordance with one-of-a-plurality of quantization schemes that is determined by the quantized level values of adjacent neighbor pels. Each of the quantization schemes is configured from ...



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