Xerox Corporation

Gte Laboratories Incorporated

To R Hsing

Jagdish C Tandon

James C Stoffel

Joseph J Daniele

Kwok L Yip

Joachim A Ritter

In a teleconferencing system activity levels of digital voice signals are compared over activity selection times and the signals are multiplied, over frame delays, by predetermined constants dependent on the relative levels of activity. The most active signal is multiplied by a constant of at least about 0.8, so that signal dominates through a frame delay, but the frame delays are sufficiently short that multiple speakers can be understood from the summed signal. No speaker maintains dominance for a sufficiently long time to substantially suppress speech of others.

Framed digital voice summing for teleconferencing

Digitally encoded voice signals are weighted dynamically in multipliers prior to summation of the digital signals. Greater weight is given to the more active channels. In one system, the signals are weighted proportionately to the square of the amplitude of each digital voice signal.

Digital voice summing for teleconferencing

An adaptive thresholder of the fractional average context type for processing image pixels in which an offset potential, which is used in conjunction with the image potentials of the nearest neighbor pixels to provide an updated threshold potential, is obtained on a pixel by pixel basis as a function of the pixel white peak and black valley potentials. The white peak and black valley potentials are compared with the image potential of each pixel being processed and with predetermined minimum white and maximum black potentials to provide updated white peak and black valley potentials for use in updating the offset potential during processing of each pixel.

Adaptive thresholder

An output scanner for producing images in response to image signals, the scanner having a high intensity illumination lamp, fiber optic bundle for converting the light output of the lamp to a succession of light rays for exposing an imaging member line by line, an electro-mechanical modulator for modulating the light rays individually in response to image signals, and a lens array for transmitting light rays from the modulator to the imaging member. The modulator comprises a full width array of closely spaced finger-like reflectors which deflect upon application of a preset potential thereto, the potential being applied to the reflectors selectively in accordance with an image signal.

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Sudbury, MA, United States of America

To R Hsing