Picturetel Corporation

Xiancheng Yuan

Jeffrey G Bernstein

Bernd Girod

Richard L Baker

Edmund S Thompson

Matthew M Bace

A method and apparatus for providing a flexible and scalable videoconferencing system for use in connection with a network provides for scalably encoding an image sequence for transmission onto the network. The encoding enables the encoded image sequence to be decoded at any one of at least two spatial resolutions and any one of at least two frame rates. The decoder, depending upon the computing platform, its resources, speed, and efficiencies, can select to decode the received image at any of the available spatial resolutions and at any of the available frame rates. A lower spatial resolution and/or a lower frame rate require less computing resources. Multiple received image sequences can be decoded simultaneously, at, for example, a lowest resolution. The decoded images can be displayed for viewing on the computer monitor at the desired spatial resolution level and frame rate.

Method and apparatus for visual communications in a scalable network

A method and apparatus for processing block coded image data wherein each block comprises a plurality of pixels. A local pixel is selected from a first block of pixels. The selected pixel is preferably near a border between the first block of pixels and a second block of pixels. At least one external pixel is selected from the second block of pixels. The selected external pixel(s) is (are) also near the border. The selected local pixel is modified to reduce the difference between the local pixel and the selected external pixel(s). The selected pixel value is modified as follows. A low pass filter coefficient is selected for each selected local pixel value and for each selected external pixel value. The selected local pixel value and the external pixel values are each multiplied by their corresponding low pass filter coefficient. The products of these multiplications are summed together to form a low pass filtered pixel value.

Method and apparatus for processing block coded image data to reduce

A method and apparatus for transmitting a sequence of image frames by encoding interframe error data features the steps of compiling a spatially decomposed image of a background of the sequence of image frames, spatially decomposing a warped image of a previous frame, and spatially decomposing a new input image. The spatially decomposed input image is compared with the spatially decomposed background image and with the spatially decomposed warped image. An error signal defining the spatially decomposed input image is generated based on these comparisons.

Hierarchical encoding method and apparatus employing background

A method and apparatus for encoding interframe error data in an image transmission system, and in particular in a motion compensated image transmission system for transmitting a sequence of image frames from a transmitter to a receiver, employ hierarchical entropy coded lattice threshold quantization to increase the data compression of the images being transmitted. The method and apparatus decimate an interframe predicted image data and an uncoded current image data, and apply hierarchical entropy coded lattice threshold quantization encoding to the resulting pyramid data structures. Lossy coding is applied on a level-by-level basis for generating the encoded data representation of the image difference between the predicted image data and the uncoded original image. The method and apparatus are applicable to systems transmitting a sequence of image frames (or other pattern data, such as speech) both with and without motion compensation.

Growing community of inventors

Bedford, MA, United States of America

Xiancheng Yuan