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  • H04N19/12—Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
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  • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
  • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
  • H04N19/176—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a block, e.g. a macroblock
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  • H04N19/179—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being a scene or a shot
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  • H04N19/186—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being a colour or a chrominance component
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  • H04N19/64—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding using sub-band based transform, e.g. wavelets characterised by ordering of coefficients or of bits for transmission
  • H04N19/647—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding using sub-band based transform, e.g. wavelets characterised by ordering of coefficients or of bits for transmission using significance based coding, e.g. Embedded Zerotrees of Wavelets [EZW] or Set Partitioning in Hierarchical Trees [SPIHT]
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  • H04N19/124—Quantisation
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  • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
  • H04N19/146—Data rate or code amount at the encoder output
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  • H04N19/42—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation

Definitions

• the present invention generally relates to the field of video data compression, and more particularly to a method and apparatus for video data compression which operates on dynamical systems, such as cellular automata (CA).
• CA cellular automata
• 3D data consisting of the "flow" of two-dimensional images (i.e., "frames") over time (Fig. 11). Thirty frames per second (fps) is the standard rate considered to define a fairly good quality video. Eighteen fps will be acceptable for certain situations. High definition video demands rates on the order of 60 fps.
• POTS Plain Old Telephone System
• a digital video stream with 640x480 frames will require four times the compression or storage requirement outlined above. Therefore, the need for fast and effective compression is apparent.
• the best approach for dealing with the bandwidth limitation and also reduce huge storage requirement is to compress the data. Since video is a conglomeration of individual picture frames, typical video compression methods are largely defined by: 1) the way the individual reference frames are encoded, and 2) the technique for relating/predicting intermediate frames together given the information about the reference frames.
• Some of the most popular techniques for compressing image data combine transform approaches (e.g. the Discrete Cosine Transform, DCT) with psycho-visual techniques.
• DCT Discrete Cosine Transform
• JPEG Joint Photographic Expert Group
• Prior patents that specifically address video compression include those of Greene (U.S. Patent No. 5,838,377), which uses the wavelets approach; and Agarwal (U.S. Patent No. 5,729,691) who taught the use of conglomeration of transforms (including DCT, Slaar and Haar transforms) for video compression.
• the present invention makes use of a transform method that uses a dynamical system, such as cellular automata transforms (CAT).
• a dynamical system such as cellular automata transforms (CAT).
• CAT cellular automata transforms
• the evolving fields of cellular automata are used to generate "building blocks" for image data.
• the rules governing the evolution of the dynamical system can be adjusted to produce "building blocks" that satisfy the requirements of low-bit rate image compression process.
• a method of compressing digital video data which includes the steps of : (a) determining a multi-state dynamical rule set and an associated transform basis function, (b) receiving input image data, and (c) performing a forward transform using the transform basis function to obtain transform coefficients suitable for reconstructing the input video data.
• a method of compressing video data which includes the steps of : (a) receiving a 3-D block of input video data, defined by directions k, I and m, the block of input video data comprised of a plurality of data frames; (b) determining a transform basis function having a size defined by N A , N,, and N m ; (c) selecting N m data frames to be compressed together; (d) dividing each data frame into N k x N, rectangles; and (e) performing a forward transform on a block of data defined by N k x N, x N law law using the transform basis function, to obtain transform coefficients suitable for reconstructing the input video data.
• An advantage of the present invention is the provision of a method and apparatus for digital video compression which provides improvements in the efficiency of digital media storage.
• Another advantage of the present invention is the provision of a method and apparatus for digital video compression which provides faster data transmission tlirough communication channels.
• Fig. 1 illustrates a one-dimensional multi-state dynamical system
• Fig 2 illustrates the layout of a cellular automata lattice space for a Class I Scheme
• Fig 3 illustrates the layout of a cellular automata lattice space for a Class II Scheme
• Fig 4 illustrates a one-dimensional sub-band transform of a data sequence of length L
• Fig 5 is a flow diagram illustrating the steps involved in generating efficient image building blocks, according to a preferred embodiment of the present invention.
• Fig 6 is a flow diagram illustrating the encoding, quantization, and embedded stream processes, according to a preferred embodiment of the present invention
• Fig 7 is a flow diagram illustrating a decoding process, according to a preferred embodiment of the present invention.
• Fig 8 illustrates interrelated factors that influence the compression process
• Fig 9 illustrates decomposition of CAT transform coefficients into 4 bands, according to a preferred embodiment of the present invention
• Fig 10 illustrates the image formed by the Group I components of Fig 9, as further CAT decomposed and sorted into another 4 groups at a lower resolution
• Fig 1 1 illustrates video data as a three-dimensional data block of two- dimensional "frames" flowing through time
• Fig 12 illustrates sub-bands m a 3D hierarchical CA transform, w herein each resolution le ⁇ el has 8 bands, and
• Fig 13 is a block diagram of an apparatus according to a preferred embodiment of the present invention.
• transform basis functions also referred to herein as "filters' ) to transform video data for the purpose of more efficient storage on digital media or faster transmission through communications channels.
• a transform basis function is comprised of a plurality of "building blocks,” also referred to herein as “elements” or “transform bases.”
• the elements of the transform basis function are obtained from the evolving field of cellular automata.
• Fig. 8 illustrates some of the costs involved in data compression techniques.
• data compression schemes seek to remove or minimize the inherent redundancy within a data string.
• efforts at compressing any data invariably come at a price.
• compression costs pertains to three interrelated factors:
• Fig. 8 degenerates into a dual-factor relationship in which more compression is typically achieved at the expense of computational ease.
• a classic example is the family of adaptive encoders. Data that is perceived (e.g., photographs, audio, and video) can often be compressed with some degree of loss in the reconstructed data. Greater compression is achieved at the expense of signal fidelity.
• a successful encoding strategy will produce an error profile that cannot be perceived by the human eye (digital images and video) or ear (digital audio). Perceptual coding becomes a key and integral part of the encoding process.
• Cellular Automata are dynamical systems in which space and time are discrete.
• the cells are arranged in the form of a regular lattice structure and must each have a finite number of states. These states are updated synchronously according to a specified local rule of interaction.
• a simple 2-state 1 -dimensional cellular automaton will consist of a line of cells/sites, each of which can take value 0 or 1.
• a specified rule usually deterministic
• the values are updated synchronously in discrete time steps for all cells.
• each cell can take any of the integer values between 0 and K - 1.
• the rule governing the evolution of the cellular automaton will encompass m sites up to a finite distance r away.
• the cellular automaton is referred to as a A " -state, -site neighborhood CA.
• Fig. 1 illustrates a multi-state one- dimensional cellular automaton.
• each set of W j results in a given rule of evolution.
• the chief advantage of the above rule-numbering scheme is that the number of integers is a function of the neighborhood size; it is independent of the maximum state, K, and the shape/size of the lattice.
• a lk are transform bases
• A: is a vector (defined in D) of non-negative integers, while c k are referred to as "transform coefficients" or "weights” whose values are obtained from the inverse transform basis function:
• transform basis function B is the inverse of transform basis function A.
• a given CA transform basis function is characterized or classified by one (or a combination) of the following features:
• transform basis functions are those with transform coefficients
• transform basis functions are generated from the instantaneous point density of the evolving field of the cellular automata.
• Other transform basis functions are generated from a multiple-cell- averaged density of the evolving automata.
• D ⁇ 1 One-dimensional ( D ⁇ 1 ) cellular spaces offer the simplest environment for generating CA transform bases. They offer several advantages, including:
• L N 2
• ⁇ 2 cells are evolved over T time steps.
• One major advantage of the latter approach is the flexibility to tie the precision of the elements of the transform basis function to the evolution time T.
• the bottom base states (with ⁇ 2 cells) shown in Fig. 3 form the initial configuration of the cellular automata.
• transform basis function types belonging to this group include:
• the transform bases A lk should satisfy:
• the inverse transform bases are:
• transform basis functions calculated from the CA states will generally not be orthogonal.
• Fig. 5 there is shown a flow chart illustrating the steps involved in generating an efficient transform basis function (comprised of "building blocks"), according to a preferred embodiment of the present invention.
• TestVideo data is input into a dynamical system as the initial configuration of the automaton, and a maximum iteration is selected.
• an objective function is determined, namely fixed file size/minimize error or fixed error/minimize file size (step 504).
• parameters of a dynamical system rule set also referred to herein as "gateway keys" are selected.
• Typical rule set parameters include CA rule of interaction, maximum number of states per cell, number of cells per neighborhood, number of cells in the lattice, initial configuration of the cells, boundary configuration, geometric structure of the CA space (e.g., one-dimensional, square and hexagonal), dimensionality of the CA space, type of the CA transform (e.g., standard orthogonal, progressive orthogonal, non-orthogonal and self-generating), and type of the CA transform basis functions.
• the rule set includes:
• Boundary conditions (BC) to be imposed.
• the dynamical system is a finite system, and therefore has extremities (i.e., end points).
• extremities i.e., end points.
• the nodes of the dynamical system in proximity to the boundaries must be dealt with.
• One approach is to create artificial neighbors for the "end point” nodes, and impose a state thereupon.
• Another common approach is to apply cyclic conditions that are imposed on both "end point” boundaries. Accordingly, the last data point is an immediate neighbor of the first.
• the boundary conditions are fixed. Those skilled in the art will understand other suitable variations of the boundary conditions.
• the dynamical system is then evolved for T time steps in accordance with the rule set parameters (step 510).
• the resulting dynamical field is mapped into the transform bases (i.e., "building blocks"), a forward transform is performed to obtain transform coefficients.
• the resulting transform coefficients are quantized to eliminate insignificant transform coefficients (and/or to scale transform coefficients), and the quantized transform coefficients are stored.
• an inverse transform is performed to reconstruct the original test data (using the transform bases and transform coefficients) in a decoding process (step 512).
• the error size and file size are calculated to determine whether the resulting error size and file size are closer to the selected objective function than any previously obtained results (step 514). If not, then new W-set coefficients are selected.
• one or more of the other dynamical system parameters may be modified in addition to, or instead of, the W-set coefficients (return to step 508). If the resulting error size and file size are closer to the selected objective function than any previously obtained results, then store the coefficient set W as BestW and store the transform bases as Best Building Blocks (step 516). Continue with steps 508-518 until the number of iterations exceeds the selected maximum iteration (step 518). Thereafter, store and/or transmit N, m, K, T, BC and BestW, and Best Building Blocks (step 520). One or more of these values will then be used to compress/decompress actual video data, as will be described in detail below.
• the initial configuration of the dynamical system, or the resulting dynamical field may be stored/transmitted instead of the Best Building Blocks (i.e., transform bases). This may be preferred where use of storage space is to be minimized. In this case, further processing will be necessary in the encoding process to derive the building blocks (i.e.. transform bases).
• the CA filter i.e., transform basis function
• the CA filters can be applied to input data in a non-overlapping or overlapping manner, when deriving the transform coefficients.
• the tacit assumption in the above derivations is that the CA filters are applied in a non-overlapping manner.
• the input data is divided into segments, where none of the segments overlap.
• the filter A of size N x N is applied in the form:
• N- ⁇ f. ⁇ ⁇ C ⁇ ⁇ l, mo ⁇ N)k ⁇ )
• CA filters can also be evolved as overlapping filters.
• the transform equation will be in the form:
• CA transform techniques seek to represent the data in the form:
• the building blocks comprising a transform basis function are received (step 602). These building blocks are determined in accordance with the procedure described in connection with Fig. 5.
• Image data to be compressed is input (step 604).
• a forward transform (as described above) is performed to obtain transform coefficients (step 606). It should be appreciated that this step may optionally include performing a "sub-band" forward transform, as will be explained below.
• c k is determined directly from the building blocks obtained in the procedure described in connection with Fig. 5, or by first deriving the building blocks from a set of CA "gateway keys" or rule set parameters which are used to derive transform basis function A and its inverse B.
• the transform coefficients are quantized (e.g., using a PsychoVisual model).
• the transform coefficients are quantized to discard negligible transform coefficients.
• the search is for a CA transform basis function that will maximize the number of negligible transform coefficients. The energy of the transform will be concentrated on a few of the retained transform coefficients.
• the quantized transform coefficients are stored and/or transmitted.
• the quantized transform coefficients are preferably coded (step 612).
• a coding scheme such as embedded band- based threshold coding, bit packing, run length coding and/or special dual-coefficient Huffman coding is employed.
• Embedded band-based coding will be described in further detail below.
• the quantized transform coefficients form the compressed image data that is transmitted/stored. It should be appreciated that steps 608, 610, and 612 may be collectively referred to as the "quantizing" steps of the foregoing process, and may occur nearly simultaneously.
• the quantized transform coefficients are transmitted to a receiving system which has the appropriate building blocks, or has the appropriate information to derive the building blocks. Accordingly, the receiving device uses the transfer function and received quantized transform coefficients to recreate the original video data.
• Fig. 7 there is shown a summary of the process for decoding the compressed video data.
• coded transform coefficients are decoded (step 702), e.g., in accordance with an embedded decoding process (step 702) to recover the original quantized transform coefficients (step 704).
• An inverse transform (equation 3) is performed using the appropriate transform function basis and the quantized transform coefficients (step 706). Accordingly, the image data is recovered and stored and/or transmitted (step 708).
• a "sub-band" inverse transform may be optionally performed at step 706, if a "sub-band” transform was performed during the encoding process described above.
• ⁇ is the probability that a transform coefficient is of magnitude i.
• ⁇ the number of times the transform coefficients attain the value (i.e., the frequency of i) is calculated. The resulting value is divided by the sum of all frequencies to obtain the pertinent probability.
• the goal is to find CA gateway keys that will result in the minimization of the entropy of the transform coefficients.
• the quantization strategy is a function of how the data will be perceived. For digital images and video, low frequencies are given a higher priority than to high frequencies because of the way the human eye perceives visual information. For digital audio both low and high frequencies are important and the transform coefficient decimation will be guided by a psycho-acoustics-based profile.
• Sub-band coding is a characteristic of a large class of cellular automata transforms.
• Sub-band coding which is also a feature of many existing transform techniques (e.g., wavelets), allows a signal to be decomposed into both low and high frequency components. It provides a tool for conducting the multi-resolution analysis of a data sequence.
• Fig. 4 shows a one-dimensional sub-band transform of a data sequence of length L.
• the data is transformed by selecting M segments of the data at a time.
• the resulting transform coefficients are sorted into two groups, namely, the transform coefficients in the even locations (which constitute the low frequencies in the data) fall into one group, and the transform coefficients in the odd locations fall into a second group.
• the locations of the low and high frequency components are reversed. In such cases the terms odd and even as used below, are interchanged.
• the "even " group is further transformed (i.e., the "even” group of transform coefficients become the new input data to the transform) and the resulting 2" '] transform coefficients are sorted into two groups of even and odd located values.
• the odd group is added to the odd group in the first stage; and the even group is again transformed. This process continues until the residual odd and even group is of size N/2.
• the N/2 transform coefficients belonging to the odd group is added to the set of all odd-located transform coefficients, while the last N/2 even-located group transform coefficients form the transform coefficients at the coarsest level. This last group is equivalent to the lowest CAT frequencies of the signal.
• L 2" transform coefficients. Therefore, in Fig. 4, at the finest level the transform coefficients are grouped into two equal low (1) and high (h) frequencies. The low frequencies are further transformed and regrouped into high-low and low-low frequencies each of size L/4.
• the process is reversed: we start from the N/2 low frequency transform coefficients and N/2 high frequency transform coefficients to form N transfomi coefficients; arrange this alternately in their even and odd locations; and the resulting N transform coefficients are reverse transformed.
• the resulting N transform coefficients form the even parts of the next 2N transform coefficients while the transform coefficients stored in the odd group form the odd portion. This process is continued until the original L data points are recovered.
• Multi-dimensional, non-overlappmg filters are easy to obtain by using canonical products of the orthogonal one-dimensional filters Such products are not automatically de ⁇ vable in the case of overlapping filters
• the CA has been evolved over 8 time steps
• the following scaled transform coefficients are obtained from the states of the cellular automata evolved by using the above rule.
• the inverse filters are obtained via a numerical inversion from the forward overlapping filters.
• the redundancy is identified by transforming the data into the CA space.
• the principal strength of CAT-based compression is the large number of transform bases available.
• Use is made of CA transform basis functions that maximize the number of transform coefficients with insignificant magnitudes. It may also be desirable to have a transform that always provides a predictable global pattern in the transform coefficients. This predictability can be taken advantage of in optimal bit assignment for the transform coefficients.
• CA CAT permits the selection of transform basis functions that can be adapted to the peculiarities of the data.
• a principal strength of CA encoding is the parallel and integer- based character of the computational process involved in evolving states of the cellular automata. This can translate into an enormous computational speed in a well-designed CAT- based encoder.
• CAT Apart from the compression of data, CAT also provides excellent tools for performing numerous data processing chores, such as digital image processing (e.g., image segmentation, edge detection, image enhancement) and data encryption.
• digital image processing e.g., image segmentation, edge detection, image enhancement
• data encryption e.g., data encryption
• the remaining transform coefficients are "high frequency" components.
• the low frequency, Group I. components can be further transformed.
• the ensuing transform coefficients are again subdivided into 4 groups, as illustrated by Fig. 10. Those in Groups II, III, and IV are stored while Group I is further CAT-decomposed and sorted into another 4 groups at the lower resolution. For an image whose size is an integral power of 2, the hierarchical transformation can continue until Group I contains only one- quarter of the filter size. In general the sub-band coding will be limited to n R levels.
• Fig. 9 represents the transform data at the finest resolution. The last transformation, at the // ⁇ -th level is the coarsest resolution.
• a picture (single frame) compression scheme will now be described in detail.
• the nature of the transform coefficients derived from a sub-band CAT coder makes it possible to impose objective conditions based on either: 1) a target compression ratio; or 2) a target error bound.
• the encoding philosophy for a sub-band coder is intricately tied to the cascade of transform coefficient Groups I, II, III, and IV shown in Figs. 9 and 10.
• the coding scheme is hierarchical. Bands at the coarsest levels typically contain transform coefficients with the largest magnitudes. Therefore, the coding scheme gives the highest priority to bands with the largest transform coefficient magnitudes.
• decoding steps for this type of an embedded scheme are implemented by generally following the natural order of the encoding process.
• decoding proceeds generally follows:
• step (i) if InputSize ⁇ TargetSize.
• the data/ is a vector of three components representing the primary colors such as RED (R), GREEN (G), and BLUE (B).
• Each of the colors can have any value between 0 and 2* - 1 , where b is the number of bits per pixel.
• Each color component is treated the same way a grayscale data is processed. It is most convenient to work with the YIQ model, the standard for color television transmission.
• the Y-component stands for the luminance of the display, while the I- and Q-components denote chrominance.
• the luminance is derived from the RGB model using
• the chrominance components are computed from:
• the advantage of the YIQ-model is the freedom to encode the components using different degrees of fidelity.
• the luminance represents the magnitude of light being deciphered by the human eye.
• the I- and Q- components represent the color information.
• the chrominance components can be encoded with a much lower degree of fidelity than the luminance portion.
• Each pixel data at the point (ij) and at a given time t can be represented by:
• N is the filter size in the respective directions. For instance, N is the filter size in the k-direction.
• transform bases A IJIklm i.e., building blocks
• IJIklm building blocks
• A" are 2D transform basis functions
• A' are ID transform basis functions.
• the 2D and ID transform basis functions are derived from a ID CAT.
• N (a) Choose the filter size N () in the respective directions.
• Each "cube” or “block” has a plurality of frames, where N is a measurement of the size of each "cube” or "block.”
• N m refers to the number of frames selected to be compressed together.
• Equation 19b Take each data block (N k x N, x N n ⁇ ) in sequence.
• 3D CAT transform of each block (Equation 19b).
• the coding scheme is also hierarchical. Bands at the coarsest levels will contain the largest transfomi coefficients.
• the coding scheme makes use of the 3-symbol alphabet system: 0 (YES), 1 (NO or POSV); and 2 (NEGV).
• the same symbol packing strategy described earlier is used to better store/transmit the decision symbols.
• the 3D viewpoint has the advantage that the transform process automatically captures all redundancies in the data in time and within the frame.
• the tasks of transfomiing the video cubes can also be carried out in parallel on a multi-processor machine. Such an approach permits real-time video transmission over a restricted bandwidth channel.
• Apparatus 100 is comprised of a receiver 102, an input device 105, a programmed control interface 104, control read only memory (“ROM”) 108, control random access memory (“RAM”) 106, process parameter memory 1 10, processing unit (PU)116, cell state RAM 114, coefficient RAM 120, disk storage 122, and transmitter 124.
• Receiver 102 receives image data from a transmitting data source for real-time (or batch) processing of information.
• image data awaiting processing by the present invention are stored in disk storage 122.
• the present invention performs information processing according to programmed control instmctions stored in control ROM 108 and/or control RAM 106.
• Information processing steps that are not fully specified by instmctions loaded into control ROM 108 may be dynamically specified by a user using an input device 105 such as a keyboard.
• a programmed control interface 104 provides a means to load additional instmctions into control RAM 106.
• Process parameters received from input device 105 and programmed control interface 104 that are needed for the execution of the programmed control instmctions are stored in process parameter memory 110.
• Transmitter 124 provides a means to transmit the results of computations performed by apparatus 100 and process parameters used during computation.
• the preferred apparatus 100 includes at least one module 112 comprising a processing unit (PU) 116 and a cell state RAM 114.
• Module 112 is a physical manifestation of the CA cell. In an alternate embodiment more than one cell state RAM may share a PU.
• the apparatus 100 shown in FIG. 13 can be readily implemented in parallel processing computer architectures. In a parallel processing implementation, processing units and cell state RAM pairs, or clusters of processing units and cell state RAMs, are distributed to individual processors in a distributed memory multiprocessor parallel architecture.

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• 2000
  • 2000-04-18 US US09/552,431 patent/US6400766B1/en not_active Expired - Fee Related
  • 2000-12-08 WO PCT/US2000/033313 patent/WO2001050767A2/en active Application Filing
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