Patents by Inventor Woo H. Paik

Woo H. Paik has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6021216
    Abstract: The effects of noise in a video processing system are reduced, resulting in improved image quality. A digital video signal containing a luminance component in Y color space is processed by increasing the amplitude of the luminance data in accordance with a nonlinear transfer function. As a result, low-amplitude components of the luminance signal are reduced. Subsequent quantization errors in transform coefficients produced by a spatial compression routine in a video encoder are consequently reduced. Inverse operations are performed at a video decoder to recover the original luminance data. The invention reduces quantization noise which is manifested particularly as dust-like variations in luminance intensity in an otherwise darkened region of a video image. A decoder apparatus is also presented.
    Type: Grant
    Filed: January 6, 1999
    Date of Patent: February 1, 2000
    Assignee: General Instrument Corporation
    Inventors: Vinay Sathe, Woo H. Paik
  • Patent number: 5909249
    Abstract: The effects of noise in a video processing system are reduced, resulting in improved image quality. A digital video signal containing a luminance component in Y color space is processed by increasing the amplitude of the luminance data in accordance with a nonlinear transfer function. As a result, low-amplitude components of the luminance signal are reduced. Subsequent quantization errors in transform coefficients produced by a spatial compression routine in a video encoder are consequently reduced. Inverse operations are performed at a video decoder to recover the original luminance data. The invention reduces quantization noise which is manifested particularly as dust-like variations in luminance intensity in an otherwise darkened region of a video image. A decoder apparatus is also presented.
    Type: Grant
    Filed: December 15, 1995
    Date of Patent: June 1, 1999
    Assignee: General Instrument Corporation
    Inventors: Vinay Sathe, Woo H. Paik
  • Patent number: 5687257
    Abstract: An apparatus and method for adaptively compressing blocks of video image data provide a local coding level for use in compressing successive blocks of video image data. Each block is preliminarily compressed using a global coding level. The preliminarily compressed data is processed to provide a measure of the randomness of an image area represented by the block of video image data. A local coding level is generated based on the randomness measure. The video image data is then compressed using the local coding level to provide compressed data for transmission. One or more intermediate compression stages can be provided, each generating an intermediate coding level, to better refine the randomness measure for use in generating the local coding level.
    Type: Grant
    Filed: November 9, 1994
    Date of Patent: November 11, 1997
    Assignee: General Instrument Corporation
    Inventors: Woo H. Paik, Edward A. Krause, Vincent Liu
  • Patent number: 5376968
    Abstract: Digital video signals are adaptively compressed for communication to a receiver. Superblocks, each containing a plurality of blocks of digital video data, are compressed using PCM, DPCM with a general motion vector for the entire superblock, and DPCM with a specific motion vector for each block contained within a superblock. The result of each compression mode is compared after accounting for overhead data, to determine which results in the least amount of data for each block. These blocks are assembled into a superblock, and compared together with necessary overhead and motion vector data to the same superblock processed using all PCM as well as the superblock processed using all DPCM. The comparison determines which compression mode produces the least amount of data for the superblock. The most compact superblock is selected for transmission.
    Type: Grant
    Filed: March 11, 1993
    Date of Patent: December 27, 1994
    Assignee: General Instrument Corporation
    Inventors: Allen Wu, Edward A. Krause, Woo H. Paik
  • Patent number: 5363408
    Abstract: A quadrature amplitude modulation (QAM) communication system is provided in which data can be communicated in any one of a plurality of QAM modes, such as 16-QAM, 32-QAM, and 64-QAM. A receiver detects the particular QAM mode transmitted on a trial and error basis, by attempting to decode the received data using different QAM modes until a synchronization condition is detected. The synchronization condition can require that a plurality of different synchronization tests be met. In a specific embodiment, a first synchronization test is met when a renormalization rate of a trellis decoder is below a threshold value. A second synchronization test is met when a first synchronization word is detected in the received data. A third and final synchronization test is met when a second synchronization word is detected in the received data. In order to reduce the cost of the receiver, most of the QAM mode dependent components are implemented using look-up tables stored in PROMs.
    Type: Grant
    Filed: March 24, 1992
    Date of Patent: November 8, 1994
    Assignee: General Instrument Corporation
    Inventors: Woo H. Paik, Scott A. Lery, John M. Fox
  • Patent number: 5321725
    Abstract: A method and apparatus for communicating high definition television signals is provided. Video signals are divided into blocks of PCM data. The PCM data is processed using motion estimation and compensation to provide DPCM data. For each block, one of PCM and DPCM data is selected for transmission based on a predetermined criteria. The selected data is compressed using the discrete cosine transform to provide blocks of transform coefficients. The coefficients are quantized to improve their coding efficiency and variable length coded. The variable length coded coefficients are coded using a concatenated coding scheme with a Reed-Solomon outer code and trellis inner code to provide coded signals for transmission. The coded signals are transmitted using QAM.
    Type: Grant
    Filed: July 10, 1992
    Date of Patent: June 14, 1994
    Assignee: General Instrument Corporation
    Inventors: Woo H. Paik, Scott A. Lery, Chris Heegard, Edward A. Krause, Jerrold A. Heller
  • Patent number: 5315388
    Abstract: A multiple serial access memory which includes a dynamic random access memory array is disclosed. The array is randomly addressed to input blocks of data. Address signals are provided to the array to output rows of data. A plurality of serial output ports are coupled to the output of the array for selectively latching different rows of data output from the array. The serial output ports are clocked to output the latched data therefrom. In an illustrated embodiment, each of the serial output ports contains a shift register having a length equal to the width of the memory array. The shift register is responsive to a first timing signal for latching a row of data from the array. A second timing signal actuates the shift register to shift a row of latched data. The serial access selector coupled to the shift register outputs a selected portion of the shifted data from the serial output port.
    Type: Grant
    Filed: November 19, 1991
    Date of Patent: May 24, 1994
    Assignee: General Instrument Corporation
    Inventors: Paul Shen, Woo H. Paik, Edward A. Krause
  • Patent number: 5311546
    Abstract: A method and apparatus are provided for adaptively equalizing data signals in a communications receiver. An unequalized data signal is demodulated. The demodulated data signal is filtered in an adaptive equalizer that initially updates adaptive filter coefficients using error signals derived from a first algorithm. A carrier lock signal is generated when a phase error of a filtered signal output from the adaptive equalizer reaches a threshold value. The adaptive filter coefficients are updated using error signals derived from a second algorithm instead of the first algorithm in response to the carrier lock signal. The first algorithm is a self-recovering equalization algorithm such as the Constant Modulus Algorithm. The second algorithm can be a decision directed algorithm. Carrier phase is recovered without the use of a phase rotator or phase de-rotator, by locating the adaptive equalizer inside of the carrier recovery loop.
    Type: Grant
    Filed: April 27, 1993
    Date of Patent: May 10, 1994
    Assignee: General Instrument Corporation
    Inventors: Woo H. Paik, Scott A. Lery, Adam S. Tom
  • Patent number: 5307375
    Abstract: A two stage accumulator is provided for updating coefficients. The accumulator is particularly useful in an adaptive equalizer. A first stage of the accumulator receives an error word and outputs sign and carry bits resulting from the addition of the error word and an N-bit LSB portion of a larger M-bit coefficient. A second stage is responsive to the sign and carry bits for updating the (M-N) MSB's of the M-bit coefficient. New error words are cyclically provided to the first stage during successive coefficient update cycles. The first stage can be implemented using an N-bit twos complement adder. The second stage can be implemented using an up/down counter. A leakage function is provided by causing the up/down counter to periodically skip over increment and decrement cycles.
    Type: Grant
    Filed: November 19, 1992
    Date of Patent: April 26, 1994
    Assignee: General Instrument Corporation
    Inventors: Allen Wu, Woo H. Paik
  • Patent number: 5291281
    Abstract: An apparatus and method for adaptively compressing blocks of video image data provide a local coding level for use in compressing successive blocks of video image data. Each block is preliminarily compressed using a global coding level. The preliminarily compressed data is processed to provide a measure of the randomness of an image area represented by the block of video image data. A local coding level is generated based on the randomness measure. The video image data is then compressed using the local coding level to provide compressed data for transmission. One or more intermediate compression stages can be provided, each generating an intermediate coding level, to better refine the randomness measure for use in generating the local coding level.
    Type: Grant
    Filed: June 18, 1992
    Date of Patent: March 1, 1994
    Assignee: General Instrument Corporation
    Inventors: Woo H. Paik, Edward A. Krause, Vincent Liu
  • Patent number: 5243624
    Abstract: Convergence of a complex adaptive equalizer used in digital communications is substantially improved by updating all coefficients of the equalizer during each filter clock cycle. Complex signal data is passed through a plurality of successive delay stages to provide N sets of delayed complex signal data. The product of each set and a complex error signal is obtained. Each product is concurrently updated with previous product data for the set to provide N sets of updated complex coefficients for selective input to equalizer filters. In an illustrated embodiment, the updated coefficients are truncated and their gain is adjusted prior to input to the filters. The updated coefficients can be multiplexed to provide a clocked stream of coefficient sets for input to the equalizer filters. A VLSI implementation of the equalizer is also disclosed.
    Type: Grant
    Filed: July 26, 1991
    Date of Patent: September 7, 1993
    Assignee: General Instrument Corporation
    Inventors: Woo H. Paik, Scott A. Lery, Allen Wu
  • Patent number: 5241563
    Abstract: An interleaver processes information in a pseudorandom order to provide pseudorandom interleaved data for communication to a deinterleaver. The pseudorandom interleaved data is processed at the deinterleaver in a pseudorandom order corresponding to that used at the interleaver means, to recover the original information. The pseudorandom processing at the deinterleaver is synchronized with the pseudorandom processing at the interleaver on a trial and error basis. In one embodiment, full synchronization occurs when a Viterbi decoder receiving data from the deinterleaver has a renormalization rate within a designated threshold and when enough synchronization words are detected in data output from the deinterleaver to meet a predetermined criterion. In another embodiment, a timer is used to initiate a new starting address for the pseudorandom processing at the deinterleaver during successive time intervals.
    Type: Grant
    Filed: August 10, 1992
    Date of Patent: August 31, 1993
    Assignee: General Instrument Corporation
    Inventors: Woo H. Paik, John M. Fox, Scott A. Lery
  • Patent number: 5241382
    Abstract: A macroblock packet format is provided for use in a digital HDTV system wherein successive video frames are divided into a plurality of macroblocks. The macroblocks comprise a plurality of superblocks, each containing a plurality of luminance and chrominance video data blocks. A DLEN field is provided in the macroblock packet format to identify the length of the macroblock packet. The packets also include variable length encoded portions of video data. The macroblock packets are transmitted in a data multiplex that also includes a next macroblock position (NMP) word. A receiver compares the DLEN information with the NMP word to verify synchronization, and reacquires the signal if synchronization has been lost.
    Type: Grant
    Filed: April 25, 1992
    Date of Patent: August 31, 1993
    Assignee: General Instrument Corporation
    Inventors: Woo H. Paik, Vincent Liu, Paul Shen, Edward A. Krause
  • Patent number: 5233348
    Abstract: Apparatus is provided for decoding variable length code words to recover transform coefficients, such as DCT transform coefficients provided by a high definition television encoder. A first category of the code words has a length of no more than n bits. A second category has a length of greater than n bits. A feedback ROM is used to decode the code words. Code words from the first category are processed by directly addressing a lookup table in the ROM. Code words from the second category are processed using multiple passes through the ROM, wherein a portion of the data output during a prior pass is fed back to address the memory during a subsequent pass.
    Type: Grant
    Filed: March 26, 1992
    Date of Patent: August 3, 1993
    Assignee: General Instrument Corporation
    Inventors: Stephen C. Pollmann, Paul Moroney, Edward A. Krause, Paul Shen, Woo H. Paik
  • Patent number: 5233629
    Abstract: Coded modulation schemes based on codes for QPSK modulation are directly incorporated into QAM based modulation systems, forming trellis coded QAM for communicating information. Concatenated coding with QPSK based trellis coding and symbol error correcting coding is used. In an encoder, an N-bit QAM constellation pattern is divided into four subsets, each including N/4 symbol points of the constellation pattern. A two-bit QPSK codeword is assigned to each of the four subsets. A symbol to be transmitted is first encoded using an outer error correcting encoding algorithm. Part of the symbol is then encoded with an inner code that comprises a rate 1/2 trellis encoding algorithm to provide a QPSK codeword, which is mapped with the remaining bits of the symbol to provide a modulation function. The remaining bits correlate the symbol with one of the symbol points included in the subset defined by the QPSK codeword. A receiver is provided to recover information from the modulation function.
    Type: Grant
    Filed: July 26, 1991
    Date of Patent: August 3, 1993
    Assignee: General Instrument Corporation
    Inventors: Woo H. Paik, Scott A. Lery, Chris Heegard
  • Patent number: 5216503
    Abstract: A multichannel image compression system uses a plurality of encoders to compress image data. A coding level command is provided to each of the encoders to specify a level of quality to be provided by each encoder. Encoded image data, provided by the encoders in response to the coding level command, is multiplexed into a combined signal for transmission. The coding level command is adjusted in response to an accumulated amount of data from the combined signal, to maintain the accumulated data within a throughput capability of a communication channel. Although the coding level command may specify a global coding level that is the same for all of the encoders, the encoders can derive local coding levels from the global coding level to provide different encoding qualities. Decoder apparatus is provided to recover an image from the compressed image data.
    Type: Grant
    Filed: December 24, 1991
    Date of Patent: June 1, 1993
    Assignee: General Instrument Corporation
    Inventors: Woo H. Paik, Edward A. Krause, Vincent Liu, Paul Shen, Henry Derovanessian
  • Patent number: 5138447
    Abstract: Digital video signals are processed by a plurality of independently operating processors to provide data for transmission in a compressed, motion compensated form. A video image frame area is divided into a set of subframes. The set of subframes is systematically shifted such that the individual subframes progressively cycle across and wrap around the video image frame area. For each successive video frame, video image data bounded by each of the different subframes is independently compressed using motion estimation to reduce data redundancy among the successive frames. The motion estimation is limited for each subframe of a current video frame to areas of a previous video frame that were bounded by the same subframe in the previous frame. In an illustrated embodiment, the set of subframes is shifted once for each successive video frame, and each subframe includes a refresh region whereby the video image frame area is progressively refreshed as the subframes are shifted thereacross.
    Type: Grant
    Filed: February 11, 1991
    Date of Patent: August 11, 1992
    Assignee: General Instrument Corporation
    Inventors: Paul Shen, Edward A. Krause, Woo H. Paik
  • Patent number: 5136411
    Abstract: A CATV system uses a single single-mode optical fiber for transmitting a composite optical signal containing television signals in different frequency channels for a plurality of subscriber terminals from a headend terminal to a distribution terminal, and converts the transmitted signals at the distribution terminal into electrical signals for distribution to a plurality of subscriber terminals over a plurality of coaxial cables. The distribution terminal further receives electrical service request signals from each of the plurality of subscriber terminals, and converts each received service request signal into an optical service request signal for transmission to the headend terminal over the same single-mode optical fiber as used from transmitting the composite optical signal. Wavelength-division multiplexer/demultiplexers couple the optical fiber to the headend terminal and the distribution terminal to enable bidirectional transmission.
    Type: Grant
    Filed: September 19, 1989
    Date of Patent: August 4, 1992
    Assignee: General Instrument Corporation
    Inventors: Woo H. Paik, David Grubb, III, David E. Charlton
  • Patent number: 5093720
    Abstract: Motion compensated coding of interlaced digital video signals is provided. Pixel data from successive interlaced video fields is compared to similarly situated pixel data in a plurality of previous fields to find a preferred counterpart for each current field set of pixel data. A prediction error signal is generated for each current field set of pixel data indicative of the difference between it and its preferred counterpart from a previous field. Each prediction error signal is encoded with data indicative of the previous field in which the preferred counterpart can be found. In a preferred embodiment, each set of current field pixel data is compared to a range of similarly situated pixels in each of the previous fields, and the prediction error signal is also encoded with motion vector data indicative of the location of the preferred counterpart in its previous field.
    Type: Grant
    Filed: August 20, 1990
    Date of Patent: March 3, 1992
    Assignee: General Instrument Corporation
    Inventors: Edward A. Krause, Woo H. Paik, Vincent Liu, James N. Esserman
  • Patent number: 5091782
    Abstract: The compression of successive blocks of digital data is optimized by selecting between different compression algorithms or different data formats on a block-by-block basis. In one application, digitized interlaced video signals are processed for transmission in a compressed form. A set of pixel data presented in a field format is compressed to provide a first compressed video signal. The set of pixel data is also presented in a frame format and compressed to provide a second compressed video signal. Errors are evaluated in the first and second compressed video signals. The compressed video signal having the least error is selected for further processing. The technique is repeated for successive sets of pixel data and the selected signals are encoded to identify them as field formatted or frame formatted signals. The encoded selected signals are then combined to provide a compressed video signal data stream for transmission. Apparatus for receiving and decoding the signals is also disclosed.
    Type: Grant
    Filed: April 9, 1990
    Date of Patent: February 25, 1992
    Assignee: General Instrument Corporation
    Inventors: Edward A. Krause, Woo H. Paik