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32 results about "Wavelet Tree" patented technology
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The Wavelet Tree is a succinct data structure to store strings in compressed space. It generalizes the π«ππ§π€q and π¬ππ₯πππq operations defined on bitvectors to arbitrary alphabets. Originally introduced to represent compressed suffix arrays, it has found application in several contexts. The tree is defined by recursively partitioning the alphabet into pairs of subsets; the leaves correspond to individual symbols of the alphabet, and at each node a bitvector stores whether a symbol of the string belongs to one subset or the other.
Adaptive down-sampling and lapped transform-based image compression method
InactiveCN101583032ASolve the problem of unsatisfactory refactoring qualityOvercome the shortcoming of poor real-time performanceTelevision systemsDigital video signal modificationImage compressionSelf adaptive
The invention provides an adaptive down-sampling and lapped transform-based image compression method, and mainly solves the problems of low performance and high complexity existing in the prior down-sampling based compression method. The method comprises the following steps of: 1, adaptively down-sampling the prior image; 2, firstly performing lapped transform on the image after adaptive down-sampling between DCT blocks which are not subjected to the down-sampling, and then performing the DCT transformation on the whole image; 3, interweaving factors after transformation into a wavelet tree structure to obtain a low frequency subband DC and a high frequency subband AC; 4, performing the shape-adaptive DCT transformation on the low frequency subband DC, and interweaving the factors again; 5, by an object-oriented SPECK coding method, coding the factors with the wavelet tree structure to obtain a compressed bit stream; and 6, decompressing the bit stream transmitted to a decoding end to obtain a final re-constructed image. The method can obtain the performance higher than that of the prior image compression method under the condition of low bit rate, is low in complexity, and can be used for the low-bit-rate image coding which has strict requirements on complexity and real-time.
Owner:XIDIAN UNIV
Wavelet domain seismic data real-time compression and high-precision reconstruction method based on compressed sensing
ActiveCN107045142AImprove wireless communication data transmission performanceSave data storage spaceCode conversionSeismic signal processingOriginal dataReconstruction method
The invention relates to a wavelet domain seismic data real-time compression and high-precision reconstruction method based on compressed sensing. The wavelet domain seismic data real-time compression and high-precision reconstruction method comprises the steps of: firstly, carrying out sparse representation on a microseismic signal in a wavelet domain; secondly, constructing a chaos Bernoulli measurement matrix (CBMM) by utilizing a Logistic chaotic sequence, and performing compressed observation on the sparsely-represented microseismic signal by using the chaos Bernoulli measurement matrix; and finally, adopting a Bayesian wavelet tree structure tree structure reconstruction method (BTSWCS), and recovering complete original data. Actual contrast experimental results show that the compression time can be shortened to 10<-5> s by using the wavelet domain seismic data real-time compression and high-precision reconstruction method for compressing data with total sampling points being 2<8>, that is, if a sampling rate of a seismometer is 1 KSPS, the CBMM measurement matrix can realize real-time compression on the acquired 0.25 s data basically. The wavelet domain seismic data real-time compression and high-precision reconstruction method increases a PSNR value by at least 5 dB, significantly improves the peak signal to noise ratio when compared with the greedy algorithm, and reduces reconstruction errors.
Owner:JILIN UNIV
Embedded type zero-type encoding method and circuit structure thereof
InactiveCN1642278AQuick codingCoding quickly implementsImage codingTelevision systemsData compressionComputer architecture
The invention relates to an embedded zero-tree coding mode and its circuit structure. It divides the embedded zero-tree coding into two processing stages, and simultaneously makes coding multiple bit planes in parallel. In the first-stage processing, firstly reading wavelet transform coefficients in a mode of scanning from low layer subband to high layer subband group by group, layer by layer and tree by tree; then executing multistage quantization for corresponding multiple threshold values; preprocessing the quantized data; after processing, independently coding the processed data on their respective bit planes; registering the symbols generated by data coding in an output buffer; after all the wavelet transform coefficients of a wavelet tree are allocated with symbols and stored into the output buffer, starting the second-stage processing; according to the scanning sequence from high layer subband to low layer subband, screening effective coded symbol output. It can raise coding rate, reduce coding time, has low requirements for IC performance and resources and is flexible to apply and easy to implement. It can be applied to the field of video data compression or image data compression.
Owner:PEKING UNIV
Method of sorting text and string searching
InactiveUS7734671B1Speed search timeEasy to searchData processing applicationsDigital data information retrievalArray data structureFM-index
A method of sorting text for memory efficient searching is disclosed. A FM-index is created on received text, and a number of rows are marked. The locations of the marked rows are stored in data buckets as well as the last column of the FM-index, which is stored as a wavelet tree. Data blocks containing the data buckets are created; containing the number of times each character appears in the data block before each data bucket. A header block is created comprising an array of the number of times each character appears in the last column of the FM-index before each data blocks, the location of the end of the data blocks and the location of the end of the data, and appended to the data block. The header and data blocks are stored. The search process loads data buckets into memory as needed to find the required text.
Owner:NATIONAL SECURITY AGENCY
Wavelet-domain video watermarking method based on fractal theory
InactiveCN106375871AEffective protectionImprove invisibilitySelective content distributionComputation complexityDecomposition
The invention relates to the technical field of processing of video images, and in particular relates to a wavelet-domain video watermarking method based on a fractal theory. In a watermark embedding process, firstly, wavelet transform of extracted key frames and watermark images is respectively carried out simultaneously; furthermore, decomposition of a wavelet tree D and a wavelet tree R is carried out; and then, direct multiplication by a strength coefficient is correspondingly embedded therein. According to the wavelet-domain video watermarking method based on the fractal theory disclosed by the invention, a method for embedding a watermark into a video is provided; therefore, the copyright of the video can be effectively protected; the problems of high video capacity, high calculation complexity and difficult watermark embedding can be solved; the watermark is embedded into the video through the method provided by the invention; the calculation amount is low; the consumed time is short; the quality of a video file cannot be influenced; the video after the watermark is embedded is high in invisibility and high in availability and robustness; and the method disclosed by the invention has a very important meaning for protecting the copyright of the video.
Owner:QINGDAO UNIV OF SCI & TECH
Wavelet Tree based network data packet indexing system
InactiveCN105718521AValid Data RetrievalWeb data indexingSpecial data processing applicationsSearch data structureNetwork packet
The present invention relates to network data analysis in the field of computer network security, and in particular, to a method for performing indexing, querying and analysis on massive network data packets. The method provided by the present invention is capable of rapidly and accurately searching out a data packet that satisfy a condition from the massive network data packets, and the method is based on a novel data structure Wavelet Tree, and indexing and querying functions are implemented by means of the data structure, wherein a process of the querying function is as shown in FIG.1. The system provided by the present invention needs relatively little space for storing an established index file, and supports various complex queries, such as an accurate query, a range query and an extreme value query for a certain attribute, and the like.
Owner:HUNAN UNIV
Coding system based on set partitioning in hierarchical tree and implementation method of coding system
ActiveCN103905819AOvercome cumbersomeOvercome inefficiencyDigital video signal modificationNODALCode module
The invention discloses a coding system based on set partitioning in a hierarchical tree and an implementation method of the coding system. The system comprises a wavelet conversion module (1), a wavelet tree extraction module (2), an importance scanning module (3) and a parallel coding module (4). The method includes the steps of firstly, inputting pixel points; secondly, conducting wavelet conversion; thirdly, extracting wavelet coefficients; fourthly, scanning the importance of the tree; fifthly, conducting paralleling coding; sixthly, outputting a code stream. In the implementation method, nodes in different bit planes share the same position information, importance information of nodes at different layers in the tree is generated through the same unit, parallel coding is conducted on different bit planes, and finally a static image is compressed. The coding system and the method have the advantages that occupied resources are less, storage efficiency is high, and the coding system and the method are particularly suitable for the spaceflight image compression field where resources are limited, space is limited and the requirement for system reliability is extremely high.
Owner:XIDIAN UNIV
Sonar image information hiding method with fractal and wavelet combined
The invention provides a sonar image information hiding method with a fractal and a wavelet combined. The method comprises the steps of (1) enabling a 3-bit binary system sequence to serve as a unit, converting information to decimal system sequences with values of 0 to 7; (2) enabling a sonar image to serve as a carrier, conducting wavelet transformation for the carrier image, dividing father-blocks and sub-blocks in different sub-band images which are arranged in the same direction of a wavelet tree; (3) using the decimal system sequences with the values of 0 to 7 to serve as classes of parameter appointed father-block affine transformation, calculating the optimal contrast ratio and luminance of the transformation blocks, replacing corresponding sub-blocks, writing down the position of the replaced sub-block; (4) sequentially processing each father-block, if the target sub-block is replaced, repeating the step of (3); (5) finishing embedding all the information, conducting wavelet inverse transformation for the carrier image, and obtaining a hiding image. According to the fact that the information is embedded through control of classes of affine transformation, an original image block with 1 bit information embedded can improvingly provided with 3 bit information in an embedded mode, and a volume for information hiding is improved.
Owner:δΈδΊεε°ζ»¨ε·₯η¨ε€§ε¦εζ΅·εζ°εε±εΊε°
Video coding method based on important probability balanced tree
InactiveCN102572423AImprove expression efficiencyReduce overheadTelevision systemsDigital video signal modificationMean squareRate distortion
The invention discloses a video coding method based on an important probability balanced tree. The method comprises the following steps: transforming 3d wavelet; weighting coefficients; constructing an important probability balanced 3d wavelet tree; initializing; searching important coefficients from the important probability balanced 3d wavelet tree and determining the sequence of the important coefficients; and detailing the amplitudes of the important coefficients. In the structure of the important probability balanced wavelet tree, through independently treating subsidiary nodes in the space direction and subsidiary nodes in the time direction, important coefficients with similar probabilities are placed in the same layer of a tree structure, so as to enable unimportant coefficients to be arranged at the tail of the tree to form zero subtree, and place important coefficients at the front end of a code stream. In the invention, relativities in dimensions and among dimensions of the coefficients are used at the same time, and synchronous information expenses are effectively reduced. Through the method provided by the invention, lower reconstruction mean square errors and better rate-distortion performance can be obtained.
Owner:LIAONING NORMAL UNIVERSITY
Compressed sensing low-field magnetic resonance imaging algorithm
InactiveCN108717171AOvercoming sensitivityOvercome shiftingMagnetic measurementsOriginal dataMinimization problem
The invention relates to a compressed sensing low-field magnetic resonance imaging algorithm. The algorithm comprises the steps that collected low-field magnetic resonance original data is subjected to undersampling, and random variable density K spacial data is obtained; undersampled K spacial data and a compressed sensing theory are combined for modeling, the modeling problem becomes a linear combination minimization problem containing a data fidelity term, a sparse prior term and a total variation term, and dual tree wavelet transformation and wavelet tree sparse joint serve as sparse transformation in the compressed sensing theory; by means of the dual tree wavelet transformation and wavelet tree sparse joint compressed sensing magnetic resonance imaging algorithm, solution is conducted, and a low-field magnetic resonance image rebuilt by the undersampled variable density K spacial data is obtained. Dual tree wavelet transformation is introduced to serve as sparse transformation ina CS-MRI model, and the defect that due to the fact that traditional wavelet transformation has sensibility and shift variant, lacks direction and has a rebuilding image, aliasing artifacts are caused is overcome. The computing accuracy is high, robustness is good, and the signal-to-noise ratio of the rebuilding image is increased while the imaging speed is increased.
Owner:UNIV OF SHANGHAI FOR SCI & TECH
Distributed image compression transmission method for wireless sensor network
InactiveCN104581167AReduce data transfer volumeBalance node energy consumptionDigital video signal modificationWireless mesh networkTransformation algorithm
The invention discloses a distributed image compression transmission method for a wireless sensor network. Based on an improved three-layer network structure, the method is characterized by comprising the following steps: automatically segmenting images by using an acquisition node on a first layer of the network based on the characteristic of images to be transmitted; sending various blocked images and compression parameters to a plurality of coding nodes of a second layer of the network; performing 9-7 lifting wavelet transform on the blocked images by various coding nodes according to the compression parameters and performing coding compression by using a layered wavelet tree set segmentation algorithm; sending coding files to a first transmission node of a third layer of the network; performing multiple hop transmission on the coding files to a target node by the transmission nodes of the third layer of the network; decoding reconstructed images of the received coding files by the target node. By combining the image blocking technology, the lifting wavelet transformation algorithm and the layered wavelet tree set segmentation algorithm, the distributed compression transmission on the images is realized, so that the network data transmission quantity is effectively reduced, the energy consumption of sensor nodes is balanced, and the network life cycle is prolonged.
Owner:SOUTH CHINA UNIV OF TECH
Self-indexer and self indexing system
InactiveUS20120265765A1Lower performance requirementsEfficiently persistedDigital data information retrievalDigital data processing detailsTheoretical computer scienceWavelet Tree
An improved self-indexer comprising a find function that caches a last found position and occurrence count of a symbol on each node level of a word-based wavelet tree for a particular symbol lookup and only uses a select function to call on data to the right of the position.
Owner:ATBROX
Seismic data compression and reconstruction method
InactiveCN107942377AMeet the needs of real-time compressionReduce storage pressureSeismic signal processingData compressionReconstruction method
The invention relates to a seismic data compression and reconstruction method. The seismic data compression and reconstruction method comprises the following steps: firstly, carrying out wavelet transformation on seismic data to increase the compressibility of the seismic data; secondly, constructing a measurement matrix capable of being realized by hardware according to a chaos sequence; carryingout compression observation on the seismic data subjected to the wavelet transformation by utilizing a chaotic measurement matrix; finally, improving a Bayesian wavelet tree structure compressed sensing reconstruction algorithm; recovering complete seismic data by utilizing an improved BTSWCS-vb algorithm. According to the seismic data compression and reconstruction method, the result of an actual data test shows that compared with a common random measurement matrix, the chaotic measurement matrix is convenient to be realized by the hardware; a plurality of chaotic measurement matrixes are adopted so that real-time compression with the seismic data compression ratio of 0.2 to 0.55 can be realized and the influence, caused by the chaos measurement matrixes, especially a Logistic sequence matrix, on a reconstruction effect, is also very good; the improved reconstruction algorithm, namely the BTSWCS-vb algorithm, is adopted so that the reconstruction precision is improved and the reconstruction time is remarkably shortened.
Owner:JILIN UNIV
Emotion recognition method based on EEG and food picture data set
InactiveCN111466931AImprove accuracySensorsPsychotechnic devicesPattern recognitionFrequency spectrum
Owner:YUNNAN UNIV
Post insulator fault identification method and device
ActiveCN110609088AAccurate identificationAnalysing solids using sonic/ultrasonic/infrasonic wavesProcessing detected response signalTime domainFrequency spectrum
The application provides a post insulator fault identification method and device. The post insulator fault identification method comprises the steps: acquiring a vibration signal of a target post insulator; carrying out N-layer wavelet packet decomposition on the vibration signal to obtain N-layer wavelet trees; performing feature extraction on the N layers of wavelet trees to obtain an energy ratio of the energy value of each frequency band in the Nth layer of wavelet to the total energy value of the Nth layer of wavelet; determining whether the target post insulator fails or not according tothe energy ratio corresponding to each frequency band; if so, carrying out time-frequency analysis on the vibration information to obtain a wavelet time-frequency diagram; and determining the fault type of the target post insulator according to the wavelet time-frequency diagram. According to the provided method, the singular point of the vibration signal of the post insulator and the frequency band included by the singular point are analyzed by combining the wavelet packet energy with time-frequency analysis and thus spectral analysis is carried out on the abnormal condition of the signal jointly from the aspects of time domain and frequency domain, so that whether the post insulator has a fault or not and the fault type are identified quickly and accurately.
Owner:YUNNAN POWER GRID CO LTD ELECTRIC POWER RES INST
Wavelet packet extraction method for grid-connected inverter network-side harmonic current information
InactiveCN105223403AReduce computationFast extractionAc/pulses peak value measurementsGrid connected inverterDecomposition
The invention discloses a wavelet packet extraction method for grid-connected inverter network-side harmonic current information. The method is based on a wavelet tree optimized decomposition and reconstruction algorithm for db4 wavelet packets. A maximum harmonic current component real-time extraction technology based on wavelet packet transform is put forward. According to the method of the invention, the wavelet frequency band, the maintaining frequency band and the zero-setting frequency band are judged by the threshold criterion after each layer of decomposition, and only the wavelet frequency band is decomposed during next layer of decomposition. The method has the advantages of small amount of decomposition operation and high wavelet decomposition precision. Compared with the prior harmonic current information extraction method, the method of the invention takes into consideration the computation limit of a digital processor, the amount of computation of decomposition and reconstruction in the process of harmonic information extraction is reduced without sacrificing the amount of maximum harmonic current information, and the method is more practical in engineering and has the advantage of high harmonic information extraction precision.
Owner:STATE GRID CORP OF CHINA +5
Astronomic tide and storm tide separating method
The invention discloses an astronomic tide and storm tide separating method. An ocean hydrometric station only measures one group of real-time tide water level processes, the real-time process can be regarded as the superposition of a strong determination process (astronomic tides) and a weak random process (atmosphere activity interference including storm tides), and at the moment, the separation can be realized by utilizing mathematical measures such as frequency windows (frequency domains) and filters (time domains). The invention adopts the separation method based on wavelet packet analysis, the tide level is used as signals, firstly, the wavelet function and the wavelet packet decomposition layer number are determined, 170 partial tides are distributed to a unique leaf node according to frequencies, an optimal wavelet tree is obtained, then, the wavelet decomposition coefficient containing the astronomic partial tides is reconstructed, astronomic partial tide signals in each frequency band range are extracted, optimally, a wavelet filter is utilized for removing the astronomic partial tides from the tide level signals, and a storm tide surge curve is obtained.
Owner:SHANGHAI OCEAN UNIV
Embedded zerotree coding method on basis of inverse Loop subdivision
The invention relates to an embedded zerotree coding method on the basis of inverse Loop subdivision, which comprises the following steps of: (1) constructing an offset wavelet tree, i.e. forming an offset d by obtaining difference of an actual vertex O and a forecast vertex O' and simultaneously, establishing a corresponding quad-tree relation of edges in each mesh Mj-1 and four edges in a thinner layer mesh Mj, wherein the offset d is generated on a corresponding edge of a delete vertex reconstruction mesh; (2) carrying out offset wavelet processing and selecting a threshold value; and (3) encoding and carrying out code-stream ordering, wherein important information is preferentially encoded by adopting an embedded encoding mode on the basis of a three-dimensional graph triangular mesh and a result obtained after compression is placed at an initial part of a code stream. The invention provides the embedded zerotree coding method on the basis of inverse Loop subdivision, through which compression efficiency is greatly improved.
Owner:ZHEJIANG UNIV OF TECH
Self-indexer and self indexing system
InactiveUS8392433B2Lower performance requirementsEfficiently persistedDigital data processing detailsSpecial data processing applicationsTheoretical computer scienceWavelet Tree
An improved self-indexer comprising a find function that caches a last found position and occurrence count of a symbol on each node level of a word-based wavelet tree for a particular symbol lookup and only uses a select function to call on data to the right of the position.
Owner:ATBROX
Color imaging system based on extended wavelet tree and color imaging method thereof
InactiveCN105915868AShorten the timeFree from lossTelevision system detailsPicture signal generatorsColor targetData acquisition
The invention discloses a color imaging system based on an extended wavelet tree and a color imaging method thereof. The color imaging system comprises a PC, a DLP, a color target image, a single-pixel photon detector and a data acquisition and control module. The PC, the DLP and the single-pixel photon detector are connected with the data acquisition and control module The important coefficients of R, G and B components are judged by utilizing the extended wavelet tree so that the number of times of sampling can be effectively reduced and no loss of important information can be guaranteed; computation overhead required by a CS algorithm can be avoided so that time required for reconstruction can be reduced; and a single-photon camera structure formed by combination of the single single-pixel photon detector and the DLP is utilized so that the system size can be reduced and the system structure can be simplified.
Owner:NANJING UNIV OF SCI & TECH
Method for detecting brain function communicated area based on signal sparse approximation
InactiveCN103006220BPrecise positioningConvenient researchDiagnostic recording/measuringSensorsData setMatrix optimization
The invention discloses a method for detecting a brain function communicated area based on signal sparse approximation. The method comprises the following steps: 1, performing wavelet packet decomposition on each time point data in a functional magnetic resonance signal to obtain a wavelet tree on original time point data; 2, carrying out sparsity measurement on nodes in the wavelet tree, and selecting the node with strongest sparsity in the wavelet tree to form an effective sparse approximation data set on original functional magnetic resonance data; and 3, carrying out hybrid matrix optimization on the formed sparse approximation data set by adopting independent content analysis, and reconstructing a source signal in a functional area in combination with an original functional magnetic resonance mixed signal to finish accurate positioning and detection of the functional area. According to the method, sparse approximation of original mixed data is obtained by utilizing the more general supposed sparsity of the functional magnetic resonance signal, and the source signal is separated through the independent content analysis and the signal reconstruction, so that the purpose of accurately positioning the brain function communicated area is achieved.
Owner:SHANGHAI MARITIME UNIVERSITY
Method and device for acquiring inherent frequency band of post insulator
ActiveCN111160315AImprove accuracySubsonic/sonic/ultrasonic wave measurementCharacter and pattern recognitionEngineeringComputational physics
The embodiment of the invention discloses a method and device for obtaining the inherent frequency band of a post insulator. The method comprises: according to a preset sampling frequency, acquiring avibration signal of a normal post insulator; carrying out wavelet packet decomposition on the vibration signal; and acquiring a multi-layer wavelet tree, acquiring each node frequency band of the last layer wavelet tree according to the sampling frequency, acquiring an energy ratio of each node frequency band, further acquiring an average energy ratio value of each node frequency band of a plurality of normal post insulators, and acquiring an inherent frequency band according to the average energy ratio value of each node frequency band. Since the inherent frequency band is the frequency bandrange acquired for a plurality of normal post insulators, whether the post insulators have defects or not can be judged through the inherent frequency band acquired by the invention, and the accuracyof a judgment result can be improved.
Owner:YUNNAN POWER GRID CO LTD ELECTRIC POWER RES INST
A Method for Separating Astronomical Tide and Storm Surge
The invention discloses an astronomic tide and storm tide separating method. An ocean hydrometric station only measures one group of real-time tide water level processes, the real-time process can be regarded as the superposition of a strong determination process (astronomic tides) and a weak random process (atmosphere activity interference including storm tides), and at the moment, the separation can be realized by utilizing mathematical measures such as frequency windows (frequency domains) and filters (time domains). The invention adopts the separation method based on wavelet packet analysis, the tide level is used as signals, firstly, the wavelet function and the wavelet packet decomposition layer number are determined, 170 partial tides are distributed to a unique leaf node according to frequencies, an optimal wavelet tree is obtained, then, the wavelet decomposition coefficient containing the astronomic partial tides is reconstructed, astronomic partial tide signals in each frequency band range are extracted, optimally, a wavelet filter is utilized for removing the astronomic partial tides from the tide level signals, and a storm tide surge curve is obtained.
Owner:SHANGHAI OCEAN UNIV
Adaptive down-sampling and lapped transform-based image compression method
InactiveCN101583032BSolve the problem of unsatisfactory refactoring qualityOvercome the shortcoming of poor real-time performanceTelevision systemsDigital video signal modificationImage compressionCompression method
The invention provides an adaptive down-sampling and lapped transform-based image compression method, and mainly solves the problems of low performance and high complexity existing in the prior down-sampling based compression method. The method comprises the following steps of: 1, adaptively down-sampling the prior image; 2, firstly performing lapped transform on the image after adaptive down-sampling between DCT blocks which are not subjected to the down-sampling, and then performing the DCT transformation on the whole image; 3, interweaving factors after transformation into a wavelet tree structure to obtain a low frequency subband DC and a high frequency subband AC; 4, performing the shape-adaptive DCT transformation on the low frequency subband DC, and interweaving the factors again; 5, by an object-oriented SPECK coding method, coding the factors with the wavelet tree structure to obtain a compressed bit stream; and 6, decompressing the bit stream transmitted to a decoding end toobtain a final re-constructed image. The method can obtain the performance higher than that of the prior image compression method under the condition of low bit rate, is low in complexity, and can beused for the low-bit-rate image coding which has strict requirements on complexity and real-time.
Owner:XIDIAN UNIV
Image compression method combining singular value decomposition and wavelet packet transformation
InactiveCN112365552AImprove refactoring qualityImprove compression qualityImage codingPictoral communicationSingular value thresholdingSingular value decomposition method
The invention discloses an image compression method combining singular value decomposition and wavelet packet transformation, and the method comprises the steps: carrying out the singular value decomposition of an original image, and decomposing the original image into a texture vector U, a geometric vector V and a singular value S; adopting an energy spectrum mode to process the characteristic value set to obtain a characteristic value set; processing the feature value set by adopting an adaptive singular value decomposition method to obtain a singular value threshold number K, and selectingthe first K feature values in the feature value set to form an approximate matrix; performing wavelet packet transformation on the first K left and right odd vectors of the approximate matrix, so thata wavelet complete binary tree can be obtained; taking the logarithm energy entropy as a cost function, sequentially comparing the logarithm energy entropy values of the child node and the father node upwards from the bottom layer of the wavelet complete binary tree, reserving the node with the smaller entropy value, deleting the node with the larger entropy value, and further obtaining an optimal wavelet tree; and reconstructing the optimal wavelet tree to obtain a reconstructed image. According to the invention, the image compression quality can be improved and a high compression ratio canbe obtained.
Owner:CHENGDU POLYTECHNIC
A Method of Information Hiding in Sonar Image Combining Fractal and Wavelet
The invention provides a sonar image information hiding method with a fractal and a wavelet combined. The method comprises the steps of (1) enabling a 3-bit binary system sequence to serve as a unit, converting information to decimal system sequences with values of 0 to 7; (2) enabling a sonar image to serve as a carrier, conducting wavelet transformation for the carrier image, dividing father-blocks and sub-blocks in different sub-band images which are arranged in the same direction of a wavelet tree; (3) using the decimal system sequences with the values of 0 to 7 to serve as classes of parameter appointed father-block affine transformation, calculating the optimal contrast ratio and luminance of the transformation blocks, replacing corresponding sub-blocks, writing down the position of the replaced sub-block; (4) sequentially processing each father-block, if the target sub-block is replaced, repeating the step of (3); (5) finishing embedding all the information, conducting wavelet inverse transformation for the carrier image, and obtaining a hiding image. According to the fact that the information is embedded through control of classes of affine transformation, an original image block with 1 bit information embedded can improvingly provided with 3 bit information in an embedded mode, and a volume for information hiding is improved.
Owner:δΈδΊεε°ζ»¨ε·₯η¨ε€§ε¦εζ΅·εζ°εε±εΊε°
Image compression method combining wavelet packet transformation and singular value decomposition
PendingCN112837386AImprove refactoring qualityImprove compression qualityImage codingSingular value thresholdingSingular value decomposition method
The invention discloses an image compression method combining wavelet packet transformation and singular value decomposition, which comprises the following steps of: performing wavelet packet decomposition on an original image to obtain a complete binary tree; taking logarithmic energy entropy as a cost function, sequentially and upwards comparing logarithmic energy entropy values of child nodes and father nodes from the bottom layer of the complete binary tree, retaining nodes with smaller logarithmic energy entropy values, deleting nodes with larger logarithmic energy entropy values, and further obtaining an optimal wavelet tree; reconstructing the optimal wavelet tree by adopting a wavelet packet reconstruction algorithm to obtain a reconstructed image; performing singular value decomposition on the two-dimensional time-frequency information of the reconstructed image to decompose the two-dimensional time-frequency information into texture vectors, geometric vectors and singular values; processing the data in an energy spectrum mode to obtain a characteristic value set; processing the feature value set by adopting a self-adaptive singular value decomposition method to obtain a singular value threshold number K, and selecting the first K feature values in the feature value set to form an approximate matrix; according to the invention, the image compression quality can be improved, and a high compression ratio can be obtained.
Owner:CHENGDU POLYTECHNIC
Full-text search method supporting search request containing missing symbols
InactiveCN102722527BMeet search needsSpecial data processing applicationsFull text searchWavelet Tree
The invention provides a full-text search method supporting a search request containing missing symbols. The full-text search method comprises the following steps: converting content symbols of a text into symbol strings, and splicing the symbol strings into a long symbol string; respectively carrying out BWT (Burrows-Wheeler transformation), (l,m)-skipping-BWT, w-ahead-BWT and SET-skipping, and w-ahead-BWT to the long symbol string; constructing a wavelet tree on the basis of the four conversion results, establishing a C table and a FT (functional test) array, and establishing a symbol rotation index; and matching the given search request with the full text, and outputting the search results, wherein the search request can contain one section or multiple sections of continuous missing symbols. The full-text search method provided by the invention supports different symbolization methods, and also supports the search request containing missing symbols, thereby meeting different kinds of search requirements.
Owner:PEKING UNIV
Video coding method based on important probability balanced tree
InactiveCN102572423BReduce overheadLow reconstruction mean square errorDigital video signal modificationMean squareWeight coefficient
Owner:LIAONING NORMAL UNIVERSITY
Real-time compression and high-precision reconstruction method of seismic data in wavelet domain based on compressive sensing
ActiveCN107045142BImprove wireless communication data transmission performanceSave data storage spaceCode conversionSeismic signal processingOriginal dataReconstruction method
The invention relates to a wavelet domain seismic data real-time compression and high-precision reconstruction method based on compressed sensing. The wavelet domain seismic data real-time compression and high-precision reconstruction method comprises the steps of: firstly, carrying out sparse representation on a microseismic signal in a wavelet domain; secondly, constructing a chaos Bernoulli measurement matrix (CBMM) by utilizing a Logistic chaotic sequence, and performing compressed observation on the sparsely-represented microseismic signal by using the chaos Bernoulli measurement matrix; and finally, adopting a Bayesian wavelet tree structure tree structure reconstruction method (BTSWCS), and recovering complete original data. Actual contrast experimental results show that the compression time can be shortened to 10<-5> s by using the wavelet domain seismic data real-time compression and high-precision reconstruction method for compressing data with total sampling points being 2<8>, that is, if a sampling rate of a seismometer is 1 KSPS, the CBMM measurement matrix can realize real-time compression on the acquired 0.25 s data basically. The wavelet domain seismic data real-time compression and high-precision reconstruction method increases a PSNR value by at least 5 dB, significantly improves the peak signal to noise ratio when compared with the greedy algorithm, and reduces reconstruction errors.
Owner:JILIN UNIV
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