Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1996-02-01
2001-01-30
Kelley, Chris (Department: 2713)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
Reexamination Certificate
active
06181747
ABSTRACT:
TECHNICAL FIELD
The present invention relates to methods and systems for encoding and decoding digital video data.
BACKGROUND ART
Video compression systems are employed to reduce the number of bits needed to transmit and store a digital video signal. As a result, a lower bandwidth communication channel can be employed to transmit a compressed video signal in comparison to an uncompressed video signal. Similarly, a reduced capacity of a storage device, which can comprise a memory or a magnetic storage medium, is required for storing the compressed video signal. A general video compression system includes an encoder, which converts the video signal into a compressed signal, and a decoder, which reconstructs the video signal based upon the compressed signal.
In the design of a video compression system, an objective is to reduce the number of bits needed to represent the video signal while preserving its visual content. Current methods and systems for video compression have achieved a reasonable quality of content preservation at a transmission bit rate of 56 kilobits per second. These methods and systems are based upon directly compressing a waveform representation of the video signal.
Motion compensation is one approach which is utilized in many video compression schemes. Current approaches model motion in terms of simple displacements of blocks or a global transformation of an entire scene to model camera motion.
SUMMARY OF THE INVENTION
The need exists for a video compression system which significantly reduces the number of bits needed to transmit and store a video signal, and which simultaneously preserves the visual content of the video signal.
It is thus an object of the present invention to significantly reduce the bit rate needed to transmit a video signal.
Another object of the present invention is to provide an efficient encoding of redundant temporal data contained within a digital video signal.
In carrying out the above objects, the present invention provides a method of encoding a video signal representative of a plurality of image frames. The plurality of image frames includes a starting frame and at least one subsequent frame. The method includes steps of identifying at least one object in the image frames, and locating a plurality of feature points of the at least one object. A step of determining a mathematical transformation which maps locations of the feature points in the starting frame to locations in each of the at least one subsequent frame is performed. The method also includes steps of encoding the mathematical transformation and a bit plane representation of the starting frame.
Further, in carrying out the above objects, the present invention provides a method of decoding an encoded representation of a plurality of image frames. The plurality of image frames includes a starting frame and at least one subsequent frame. The method includes a step of receiving an encoded signal containing an encoded bit plane representation for the starting frame and an encoded mathematical transformation. A step of decoding the encoded bit plane representation is performed to extract a bit plane representation for the starting frame. A step of decoding the encoded mathematical transformation is performed to extract a mathematical transformation which maps locations of feature points in the starting frame to locations in each of the at least one subsequent frame. A step of transforming the bit plane representation of the starting frame in accordance with the mathematical transformation is performed to form a bit plane representation for each subsequent frame.
Further in carrying out the above objects, systems are provided which perform the steps of the above-described methods.
Embodiments of the present invention advantageously produce high compression rates for coding small object motions or deformations in video and film digital data. A practical temporal description of quasi-rigid, as well as rigid body motion for generic objects that are constant during a sequence of interest, i.e., objects which are neither created nor destroyed during the sequence being coded, is provided. The motion is based on actual object deformation rather than artificial motion descriptions based on arbitrary block matching techniques. This approach complements methods that provide a global description of camera motions such as zoom and pan.
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Crook John A.
Hughes Electronics Corporation
Kelley Chris
Sales Michael W.
Wong Allen
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