Canon Kabushiki Kaisha

James David Clark

James Philip Andrew

Timothy Merrick Long

George Politis

Kevin John Moore

Peter William Mitchell Ilbery

Peter Leslie Bell

A method of determining a quality value for an image frame is disclosed. The method comprises dividing (in a step) the frame into a plurality of tiles () and determining attributes (in a step) of each said tile based upon pixel values of the tile, and pixel values of a corresponding tile of a preceding frame. The method then establishes (in steps) the quality value of the frame by testing the tile attributes of the frame against pre-determined criteria. The method then defines (in a step) the quality value of the frame depending upon results of the testing.

Method for detecting and selecting good quality image frames from video

The method compresses image data into a fixed sized memory. The image is encoded in scans, where the scans are ordered from a perceptually most significant scan to a perceptually least significant scan. The scans also have an attributedetermining whether a scan is active or inactive. The method comprises an encoding, transferring and setting step. The encoding stepencodes active scans of image data into scan bit-stream data. The transferring steptransfers the encoded scan bit-stream data to the fixed size memory. The setting stepsets, if the fixed size memory becomes full, the attribute of a perceptually least significant scan to inactive.

Compression into a fixed size buffer

An apparatus includes a DCT unit for transforming blocks of pixels into respective blocks of transform coefficients, entropy encoders for encoding respective partitions of the DCT blocks where at least one partition comprises bit-plane data from each block of transform coefficients, and a scan output manager for storing the entropy encoded partitions in a buffer of fixed memory size. The manager manages the storing of the coded partitions in the buffer whereby during the storing of the coded partitions if it is determined the buffer is full, a coded least perceptually significant partition currently stored in the buffer is overwritten by data from a coded more perceptually significant partition.

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Fairlight, Australia

James David Clark