Polycom, Inc.

Picturetel Corporation

Edmund S Thompson

Yibo Liu

Peter L Chu

Jinwei Feng

Xiangdong Wang

Jeffrey G Bernstein

Richard L Baker

Bernd Girod

Yipeng Liu

Xiancheng Yuan

Antony Henry Crossman

A videoconference apparatus and method coordinates a stationary view obtained with a stationary camera to an adjustable view obtained with an adjustable camera. The stationary camera can be a web camera, while the adjustable camera can be a pan-tilt-zoom camera. As the stationary camera obtains video, participants are detected and localized by establishing a static perimeter around a participant in which no motion is detected. Thereafter, if no motion is detected in the perimeter, any personage objects such as head, face, or shoulders which are detected in the region bounded by the perimeter are determined to correspond to the participant.

People detection method for auto-framing and tracking in a video conference

Blurriness in a video image transmitted over a lossy network can be reduced by filtering the decoder output to determine whether updating of the reference frame based on the current video data is indicated. An update may be appropriate if the decoder output is sharper than the contents of the display buffer after the last update. Additionally, an update may be appropriate if there was a significant change to the underlying image, and thus to the encoder's input. Whether such a change has occurred can be determined by analyzing the prediction mode, motion vectors, and pixel data of the output image.

Lossy channel video blur avoidance

A videoconferencing system includes at least one processor and at least one camera. The endpoint can capture one or more images with the camera. The system can locate a region of interest within an image, such as the area surrounding the face of a person participating in a videoconference. If the face area or other region of interest is too dark, the system can brighten the region to make it more visible. The system can determine whether the face is too dark by comparing the captured image to previously captured images, or comparing the luma values and other data making up the face to predetermined values, or both. The system can check the second image for over-brightening or saturation, and further adjust the image as needed. The brightening of the face area is done in such a way that the brightened region is unobtrusive to the viewer.

System and method for brightening video image regions to compensate for backlighting

A videoconferencing system includes at least one processor and at least one camera. The endpoint can capture one or more images with the camera. The system can locate a region of interest within an image, such as the area surrounding the face of a person participating in a videoconference. If the face area or other region of interest is too dark, the system can brighten the region to make it more visible. The system can determine whether the face is too dark by comparing the captured image to previously captured images, or comparing the luma values and other data making up the face to predetermined values, or both. The system can check the modified image for over-brightening or saturation, and further adjust the image as needed. The brightening of the face area is done in such a way that the brightened region is unobtrusive to the viewer.

The error concealment technique disclosed herein relates to the use of existing information by the decoder to conceal bitstream errors regardless of what the encoder does. Examples of existing information include, for example, the previous reference frame, macroblock information for the previous reference frames, etc. Another aspect of the system described herein relates to the steps that the encoder can take to enhance the decoder's ability to recover gracefully from a transmission error. Exemplary steps that can be taken by the encoder include intra walk around and sending GOB headers. Although these encoder techniques can provide greatly enhanced results, they are not strictly necessary to the system described herein.

Error concealment in a video decoder

A method and apparatus for allocating transmission bits for use in transmitting samples of a digital signal. An aggregate allowable quantization distortion value is selected representing an allowable quantization distortion error for a frame of samples of the digital signal. A set of samples are selected from the frame of samples such that a plurality of the selected samples are greater than a noise threshold. For each sample of the set, a sample quantization distortion value is computed which represents an allowable quantization distortion error for the sample. The sum of all sample quantization distortion values is approximately equal to the aggregate allowable quantization distortion value. For each sample of the set, a quantization step size is selected which yields a quantization distortion error approximately equal to the sample's corresponding quantization distortion value. Each sample is then quantized using its quantization step size. An estimation signal is prepared which is representative of the digital signal but has fewer samples than the digital signal. A signal index is prepared which represents, for at least one sample of the estimation signal, the magnitude of a signal component relative to the magnitude of a noise component. Based on the signal index, samples of the digital signal are selected which have a sufficiently large signal component. The selected samples of the digital signal and the samples of the digital estimation signal are both transmitted to a remote device. The remote device reconstructs the digital signal from the transmitted selected samples and estimation samples.

Variable bit rate speech encoder

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.

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Burlington, MA, United States of America

Edmund S Thompson