Patents by Inventor Oscar Chi-Lim Au

Oscar Chi-Lim Au 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).

  • Device, method and digital video encoder for block-matching motion estimation
    Patent number: 6842483
    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.
    Type: Grant
    Filed: September 11, 2000
    Date of Patent: January 11, 2005
    Assignee: The Hong Kong University of Science and Technology
    Inventors: Oscar Chi-Lim Au, Ming Lei Liou, Alexandros Tourapis, Guobin Shen
  • Methods and apparatus for hiding data in halftone images
    Patent number: 6690811
    Abstract: We propose modifying the error-diffusion method for transforming a grey-scale image into a halftone image, so that binary data is hidden in the resulting halftone image. Simultaneously, a second halftone image is generated by error diffusion, not storing the hidden data. The hidden binary data is typically a binary image, and the dark regions of this binary image can be seen when the two halftone images are overlaid.
    Type: Grant
    Filed: December 8, 2000
    Date of Patent: February 10, 2004
    Assignee: The Hong Kong University of Science and Technology
    Inventors: Oscar Chi-Lim Au, Ming Sun Fu
  • Methods and apparatus for hiding data in halftone images
    Publication number: 20020106102
    Abstract: We propose modifying the error-diffusion method for transforming a grey-scale image into a halftone image, so that binary data is hidden in the resulting halftone image. Simultaneously, a second halftone image is generated by error diffusion, not storing the hidden data. The hidden binary data is typically a binary image, and the dark regions of this binary image can be seen when the two halftone images are overlaid.
    Type: Application
    Filed: December 8, 2000
    Publication date: August 8, 2002
    Inventors: Oscar Chi-Lim Au, Ming Sun Fu