US5228098A — Adaptive spatio-temporal compression/decompressio…

Claim 1

Independent Claim 144 words

A method of adaptive spatio-temporally compressing/decompressing an image defined as an array of picture elements comprises the steps of: defining blocks of the picture elements as intermediate nodes and leaves according to a spatial quadtree hierarchy until all intermediary nodes are resolved into leaves, each leaf having an associated intensity value; assigning for each leaf a temporal bit indicative of whether a significant change in the intensity value has occurred between successive frames of the image; and encoding the intermediary nodes and leaves into a compressed data stream representative of the image having a first bit value for each intermediary node starting from the highest level of the spatial quadtree hierarchy and a second bit value for each leaf, each leaf where the temporal bit indicates the significant change being followed by a plurality of bits representing a new intensity value for that leaf.

Claim 2

Independent Claim 144 words

A method of adaptive spatio-temporally compressing/decompressing an image defined as an array of picture elements comprises the steps of: defining blocks of the picture elements as intermediate nodes and leaves according to a spatial quadtree hierarchy until all intermediary nodes are resolved into leaves, each leaf having an associated intensity value; assigning for each leaf a temporal bit indicative of whether a significant change in the intensity value has occurred between successive frames of the image; and encoding the intermediary nodes and leaves into a compressed data stream representative of the image having a first bit value for each intermediary node starting from the highest level of the spatial quadtree hierarchy and a second bit value for each leaf, each leaf where the temporal bit indicates the significant change being followed by a plurality of bits representing a new intensity value for that leaf.

Claim 3

Dependent Claim 52 words

A method as recited in claim 1 further comprising the step of decoding the compressed data stream by detecting each leaf where the temporal bit indicates the significant change and determining the corresponding range of addresses in a memory for updating the intensity values of the image with the new intensity value.

Claim 4

Dependent Claim 126 words

A method as recited in claim 2 wherein the decoding step comprises the steps of: initializing a decoder algorithm at the beginning of each frame of the image within the compressed data stream; testing each bit of the compressed data stream in sequence until a bit indicating a leaf is found; determining from the temporal bit of the leaf whether the new intensity value is present; specifying a block size indicating the number of pixels in the leaf and an address representing a starting location in the memory for the leaf; replacing the intensity values for the pixels of the leaf specified by the block size and address with the new intensity value; and repeating the testing and replacing steps until the image frame is complete.

Claim 5

Dependent Claim 60 words

A method as recited in claim 3 wherein the testing step comprises the steps of: checking the bit from the sequence to determine if it represents an intermediary node; decreasing the block size by a factor of two when the checked bit represents the intermediary node; and going on to the determining step when the checked bit represents the leaf.

Claim 6

Independent Claim 183 words

An apparatus for adaptive spatio-temporal compressing/decompressing of an image comprising: means for converting a signal representing the image into a digital data stream representing intensity values for each pixel of the image; means for storing a sequential portion of the digital data stream representing a frame of the image; means for determining temporal difference values for the pixels between two frames of the image; means for encoding the digital data stream into a compressed data stream as a function of the temporal difference values using a quadtree hierarchy of intermediary nodes and leaves, each leaf including a temporal bit indicative of a significant change in the intensity values for that leaf between the two frames, the compressed data stream having a single bit for each intermediary node of the quadtree of a first value, two bits for each leaf with the first bit being of a second value and the second bit being the temporal bit, and a plurality of bits representing a new intensity value for the leaf after each pair of leaf bits where the temporal bit has a specified value.

Claim 7

Independent Claim 183 words

An apparatus for adaptive spatio-temporal compressing/decompressing of an image comprising: means for converting a signal representing the image into a digital data stream representing intensity values for each pixel of the image; means for storing a sequential portion of the digital data stream representing a frame of the image; means for determining temporal difference values for the pixels between two frames of the image; means for encoding the digital data stream into a compressed data stream as a function of the temporal difference values using a quadtree hierarchy of intermediary nodes and leaves, each leaf including a temporal bit indicative of a significant change in the intensity values for that leaf between the two frames, the compressed data stream having a single bit for each intermediary node of the quadtree of a first value, two bits for each leaf with the first bit being of a second value and the second bit being the temporal bit, and a plurality of bits representing a new intensity value for the leaf after each pair of leaf bits where the temporal bit has a specified value.

Claim 8

Dependent Claim 33 words

An apparatus as recited in claim 5 further comprising means for decoding the compressed data stream to update a display memory at those locations representative of a leaf having the new intensity value.

Claim 9

Dependent Claim 80 words

An apparatus as recited in claim 6 wherein the decoding means comprises: means for identifying the leaf having the new intensity value from the compressed data stream; means for generating a start address for the display memory for the identified leaf; means for generating a block size from the identified leaf; and means for extracting the new intensity value from the identified leaf for storage in the display memory in locations determined by the start address and the block size.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1996-07-12	1997-01-11	1997-07-13	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2000-07-12	2001-01-11	2001-07-13	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2004-07-12	2005-01-11	2005-07-13	$7700.00	Window Closed / Lapsed

Adaptive spatio-temporal compression/decompression of video image signals

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