248 results about "Discrete cosine transformation" patented technology

The invention belongs to the technical field of vision measurement, in particular to an automatic focusing method. In the method, an idea, which comprises that an image definition evaluation function is designed on the basis of improved discrete cosine transformation (DCT) to represent detail information of the image and highlight high frequency energy, and the relative definition is brought in by consideration of a close relation between the definition of the image and the brightness and the gray scale of the image, is provided. Meanwhile, in the method, a scale-variable window selecting scheme is provided on the basis of analyzing the influence from the selection of a focusing window on a focusing result. Experimental results show that the effect of the improved image definition judgment is improved greatly; in the actual application of the method, a partial extreme value of the image definition judgment is hard to avoid, so, by combining return information of a lens, an improved climbing method search strategy of total-range rough adjustment large step length focusing and partial refine adjustment small step length focusing is provided; and in the method, a scheme of starting automatic focusing when a shooting scene is changed or the lens is zoomed is provided.

Provided are a method and apparatus for image encoding which improves encoding efficiency in accordance with image characteristics by performing prediction in lines and performing a one-dimensional transformation in lines on an input image, and a method and apparatus for image decoding. Encoding efficiency of an image may be improved by generating a prediction sub residual block using neighboring residues and performing a one-dimensional discrete cosine transformation (DCT) on a difference residual block which is a difference between an original sub residual block and the prediction sub residual block.

A method and apparatus for classifying mood of music at high speed. The method includes: extracting a Modified Discrete Cosine Transformation-based timbre feature from a compressed domain of a music file; extracting a Modified Discrete Cosine Transformation-based tempo feature from the compressed domain of the music file; and classifying the mood of the music file based on the extracted timbre feature and the extracted tempo feature.

The invention discloses a picture similarity calculation method, comprising the steps of: (1) calculating hash values of two pictures to be compared by using a hash method based on DCT (Discrete Cosine Transformation); (2) calculating the Hamming distance dis-h between the two hash values; (3) if the Hamming distance is not in a set range, directly calculating the similarity of the two pictures via a formula; (4) if the Hamming distance is in the set range, calculating a hash value by using a hash method based on radial projection; and (5) calculating a Pearson's correlation coefficient of the hash value obtained last step, and calculating the similarity of the two pictures in combination with the Hamming distance obtained in step 2. The method has certain robustness for image rotation, avoids the influence caused by gamma correction or color histogram adjustment, and improves the accuracy of picture similarity results.

The invention discloses a polyethylene glycol terephthalate (PET) reconstruction method based on a sparsification and Poisson model. The PET reconstruction method includes: firstly, acquiring projection data, determining image size range and pixel range, and calculating a system probability matrix; obtaining an initial image through a filtered back projection (FBP) traditional algorithm, and using an obtained log-likelihood function as a reconstruction recovery item; using a wavelet transformation and discrete cosine transformation (DCT) mixed base and weighting as sparse regularization constraint, decomposing an objective function by using a split Bregman method to obtain two sub-problems, using a first sub-problem as a sparse regularization problem under a Gaussian model, and using linear Bregman interation for solving; using a second sub-problem as a Poisson denoising problem, and using a close operator method for solving; operating the last one iterative formula, completing an integrated iteration, obtaining a reconstructed image, and serving as an initial value of the next iteration.

The invention discloses a transform domain quadratic estimation method uniting weighted threshold de-noising and balanced decision. The method comprises the following steps: step 1), uniting a superimposed training sequence and a harmonic sequence and generating a sending sequence; step 2), in an OFDM (Orthogonal Frequency Division Multiplexing) baseband system, through an estimation method of an LS channel of the superimposed training sequence, obtaining coarse estimation of a channel frequency response; step 3), performing amplitude phase compensation on the coarse estimation of the channel frequency response, adding a window function with a width of M and performing DCT (Discrete Cosine Transformation) of an M point, performing low-pass filtering, time domain de-noising and sequence zero padding extension processing on the obtained sequence, performing N point IDCT (Inverse Discrete Cosine Transform), window removing and secondary amplitude phase compensation on an extended N point sequence, as the following formula, and obtaining the following formula; step 4), performing balanced decision on the obtained result and obtaining the following formula, repeating M point DCT, low-pass filtering, time domain de-noising, interpolation zero padding and N point IDCT, and obtaining a final estimation of a frequency domain response, as the following formula. The transform domain quadratic estimation method uniting the weighted threshold de-noising and the balanced decision provided by the invention eliminates the influence of a data sequence and the training sequence on the channel estimation performance, improves the performance of the existing LS (Least Squares) channel estimation, and has lower implementation complexity.

The invention relates to a high-robustness digital watermarking method making a color QR code embedded in a color image. Based on a color QR code, a Contourlet transformation technology, a DCT (discrete cosine transformation) technology and an SVD (singular value decomposition) transformation technology, the color QR code is adopted as original watermark information. The method includes the following steps that: a color host image and the color QR code are water-marked in an RGB space so as to be subjected to three-channel decomposition, and three-channel watermarks obtained after the decomposition are subjected to chaotic encryption separately; Contourlet transformation is performed on each channel image of the color host image, and DCT is performed on the low-frequency components of the channel images, and the direct-current components of the channel images are adopted to construct new matrixes, SVD transformation is performed on the new matrixes, so that singular value matrixes can be obtained; and the watermarks are embedded into corresponding channels, SVD inverse transformation, inverse DCT, and Contourlet inverse transformation are carried out, so that the color image containing the watermarks can be obtained. Compared with an existing algorithm for embedding color watermarks into a color image, the high-robustness digital watermarking method of the invention has the advantages of high imperceptibility and high robustness.

The invention discloses a high-performance macroblock coding implementation method, which mainly solves the problems of low processing speed, complexity in implementation, and a large number of occupied resources of the conventional method for implementing macroblock coding based on hardware. The method is implemented by the following steps of: (1) caching initial data and inter prediction data; (2) performing two-path parallel intra prediction on the current macroblock; (3), selecting the optimal mode of the intra prediction and cost thereof according to the intra prediction result; (4), acquiring the optimal mode of the inter prediction and cost thereof; (5), comparing the cost of the optimal modes of the inter prediction and the intra prediction to obtain the optimal prediction modes of the current macroblock; and (6) quantizing discrete cosine transformation (DCT) results of the optimal prediction modes and performing entropy coding and reestablishing respectively and depositing and outputting the reestablished results simultaneously. The method has the advantages that coding speed is high, a field programmable gate array (FPGA) is easy to implement and resources are fully reused, and can be used for a video coding system, particularly the video coding system with high resolution.

The invention discloses a real-time compression method of three-dimensional sonic logging data, which comprises the following steps: dividing data to be compressed into data to be compressed, which have the length of m, by splitting original sonic data into retention data with a high n1 bit and the data to be compressed, which have a low n2 bit; then carrying out DCT (discrete cosine transformation) on the data to be compressed according to groups to obtain mapping data, quantifying the mapping data, i.e. retaining more bit numbers for the data with larger numerical value while retaining less bit numbers for the data with smaller numerical value, realizing the real-time compression of the data and coding the data after being quantified; and finally, merging the retention data with the high n1 bit in retention data number groups and the data after being coded so as to obtain compressed data. Therefore, the storage quantity and the transmission quantity of data are reduced, and the logging efficiency is enhanced.

The invention belongs to the technical field of image processing and information security and relates to a mosaic image detection method and system based on local two-dimensional characteristics. The mosaic image detection method includes that images are cut through squares with different side lengths and then are subjected to blocking Discrete Cosine Transformation (DCT), and the obtained blocked DCT coefficients are described in a local two-dimensional characteristic mode, are merged to be an integral detection characteristic and then are classified by a classifier. The mosaic image detection method and system can consider both the detection accuracy and the detection complexity, and the detection accuracy can reach 89.9%.

The embodiment of the invention discloses a video tampering detection method based on a compressed sensing semi fragile watermark, which comprises the steps of: extracting an MPEG-2 (Moving Picture Experts Group) compressed video, extracting image characteristics of a frame I through a compressed sensing technology on the basis of a coding mode of a frame I image and a characteristics of a DCT (Discrete Cosine Transformation) coefficient, generating and embedding two watermarks of a content authorization watermark and an integrity watermark; carrying out initial check on video integrity, inter-frame taper detection on the video and intra-content authorization on the video, and finally outputting a detection result and carrying out MPEG-2 decompression on the video. By implementing the invention, the image characteristics of the frame I are extracted by using the compressed sensing technology on the basis of the coding mode of the frame I image and the characteristic of the DCT coefficient, a semi-fragile content authorization watermark is generated, and then embedded in medium-high frequency coefficients of each macro block of the frame I image; and based on a motion vector characteristic of a frame P, Hash operation is carried out a sequence number of the frame P, the obtained key value is used as the integrity watermark to be embedded in a motion vector of the frame P, thus intra-frame taper detection is realized in the frame I, and inter-frame taper detection is realized in the frame P.

The invention provides an H.264 downsizing transcoding method based on texture and motion characteristics, and belongs to the technical field of computer digital video transcoding. The invention specifically comprises the following steps: (1) acquiring the coding information input into the H.264 code stream; wherein, the coding information includes an inter-frame coding mode, motion vectors and discrete cosine transformation coefficients; (2) dividing the motion area and the background area according to the image texture characteristics by means of the motion edge detection; (3) adopting the corresponding inter-frame mode according to the motion characteristics of the macro-blocks located in different areas, particularly, reconstructing the motion vectors by the adaptive motion vector re-sampling method or the align-to-worst weighting method according to the motion difference of the macro-blocks located in the motion area, reconstructing the motion vectors of the macro-blocks located in the background area by the align-to-average weighting method, and carrying out the motion search of the macro-blocks located on the edge of the motion object and the internal macro-blocks. Compared with other methods, the method of the invention can not only guarantee the quality of the transcoded video, but also effectively solve the problem of the downsizing transcoding real-time performance.

The invention discloses a self-adaptive robust video watermarking method based on AVS (Audio Video Standard), which mainly solves the problems of high complexity, non-blindness, great gap between the current method and the AVS, and the like in the current method. When watermarks are embedded, a discrete cosine transformation low-frequency coefficient visual masking value corresponding to each subblock of video frame I is firstly calculated according to a Watson model; the energy of each subblock is sequenced in a descending order; and a large-energy subblock is selected as a watermark embedding position to be in secret key storage. Watermark embedding strength is controlled through the low-frequency coefficient visual masking value in a self-adaptive manner so as to embed the watermarks. When the watermarks are extracted, the embedded watermarking subblocks are found according to the secret key at first; and then the watermarks are extracted through comparing the relation between the subblock discrete cosine transformation low-frequency coefficient and a threshold value. In the invention, the watermark embedding and extracting arithmetic is simple; the embedding position and strength are self-adaptive; with better transparency, robustness and real-time property, the method belongs to original basic research work and meets the copyright protection needs of mass video products after the large-scale popularization and commercial application of the AVS; and the method has broad market application prospect.

The invention discloses an H.264 video watermark embedding and extraction method based on mixed coding/decoding and belongs to the field of multimedia information safety. According to the scheme, video data are not required to be thoroughly decoded, coding parameters of an original video are fully utilized during watermark embedding, and difference between a video with an embedded watermark and the original video is reduced to the greatest extent. During decoding, not all of the video data are decoded, and only discrete cosine transformation (DCT) data are decoded. During the watermark embedding, the coding parameters such as a block type, a prediction mode and a motion vector in a decoding process are kept, and the watermark embedding is quickly realized. Compared with a conventional video watermark scheme in which all of the video data are required to be decoded, a video watermark scheme based on a 264 video compression standard provided by the invention is higher in speed and higher in efficiency.

The invention provides a video compression and decompression method based on fractal and H.264. Intra prediction of coding based on the H.264 is adopted for an I frame to obtain a prediction frame. A block motion estimation or complementary coding which are based on fractal is used for obtaining a prediction frame of a P frame. Difference between each initial frame and each corresponding prediction frame is a residual frame. After the residual frames are transformed through discrete cosine transformation (DCT) and are quantified, on one hand, the residual frames are written in a code rate, on the other hand, the residual frames are inversely quantified and reversely transformed though the DCT and then plus the prediction frames to get rebuilt frames (as reference frames). Fractal parameter is generated when the P frame is encoded in a predictive mode, the residual frames of the I frame and the P frame are compressed by the utilization entropy encoding CALCV, and the fractal parameter is compressed by utilization of an exponential-Golomb code with symbols, and a corresponding decompression process is that a prediction frame is obtained from an intra prediction of the I frame, and a prediction frame is obtained by a prediction of a frame in front of the P frame. Residual information in the code rate is reversely quantified and reversely transformed through the DCT to respectively obtain the residual frames of the I frame and the P frame.

A low-power and high-quality DCT transformation based on the Cordic method is presented. The proposed Cordic based Loeffler DCT architecture only requires 38 add and 16 shift operations to carry out the DCT transformation. The complexity is almost the same as the complexity of the binDCT-C5. The simulation results show that the DCT according to the invention reduces the area and the power dissipation of the implementation compared to the original Loeffler DCT significantly. Furthermore, it only has a fraction of the power dissipation of the binDCT-C5. The major contribution of the DCT according to the invention is that it not only reduces the area and power consumption significantly, but also keeps the good transformation quality of the original Loeffler DCT. It is worth noticing that the Cordic based Loeffler DCT according to the invention is very suitable for low-power and high-quality CODECs in multimedia hand-held systems.

The invention discloses a transfer coder adaptive to a high efficiency video coding (HEVC) standard and mainly solves the problems in the prior art that transfer blocks are different in sizes and too many multipliers are used. The transfer coder adaptive to the HEVC standard comprises a one-dimensional discrete cosine transformation/ discrete sine transformation (DCT/DST) module (1), a transposing bugger module (2) and a top layer control unit (3). The one-dimensional DCT/DST module (1) is provided with a unified HEVC transfer coding framework and is combined with a butterfly-shaped structure and a matrix multiplication array to achieve resource selection sharing. The transposing bugger module (2) uses path delay between registers and different storing and reading sequences of storages to finish transposing operation of data efficiently, simply and conveniently. The top layer control unit generates rest signals and enable signals of the one-dimensional DCT/DST module and the transposing bugger module, controls the one-dimensional DCT/DST module to perform one-dimensional row transfer for input data and controls the transposing bugger module to transpose the transfer results and output the transfer results to the one-dimensional DCT/DST module so as to finish one-dimensional rank transfer. The transfer coder has the advantages of being simple and ordered in structure, high in reuse degree and capable of achieving integrated circuits, and can achieve high-throughput transfer coding.

The invention provides a quick fractal video compression and decompression method, comprising the following steps: firstly, coding an initial frame by block DCT (discrete cosine transformation); carrying out block movement estimation/ compensation coding on a non-I frame; calculating the pixel sum and the pix quadratic sum of a sub block relevant to a sub block region and a father block region; meanwhile, calculating the pixel sum and the pixel quadratic sum of the interpolated value corresponding block of a subpixel; then, carrying out preview search restricted condition judgment; finding the most similar matching block in a previous frame of search window by an unsymmetrical cross-shaped multi-level hexagon lattice point search algorithm matched and improved by a subpixel block; and finally, compressing an iterated function system coefficient by a Huffman coding method. The corresponding decompression process comprises the following steps: decoding the I frame in an inverse DCT mode; performing Huffman decoding on the non-I frame to obtain the iterated function system coefficient; then, decoding on the basis of a macroblock; calculating the pixel sum and the pixel quadratic sum of a relevant sub block in the father block region; then, successively decoding each macroblock in the current frame; and utilizing a deblocking loop filter method.

The invention discloses a method for achieving MFCC (Mel Frequency Cepstrum Coefficient) parameter extraction by a field-programmable gate array. The method belongs to a signal processing technology of an electronic information. The device comprises pre-emphasis processing, framing processing module and the like, the parameter extraction method comprises the following steps of: carrying out the pre-emphasis processing, carrying out the framing processing, carrying out the windowing processing, carrying out discrete power spectrum estimation, carrying out Mel triangular filter bank filtering, carrying out natural logarithm and discrete cosine transform on a voice signal of to-be-extracted MFCC characteristic parameters to obtain the MFCC parameters. The invention has the beneficial effects that some modules developed by Xilinx are embedded in a Simulink bank by improving each part of data processing modules and by means of a System Generator development tool of an Xilinx company, fixed-point simulation is carried out in Simulink, and HDL (Hardware Description Language) files are generated and called in ISE, development of an MFCC characteristic extraction hardware is rapidly achieved, a signal processing speed and a research and development period are improved.

The invention discloses a transition coder applicable to HEVC ( high efficiency video coding) standards and mainly solves the problems of multiple use of multipliers and a complicated circuit in the prior art. The transition coder comprises a one-dimensional DCT (discrete cosine transformation) module (1), a transposition buffer module (2) and a top layer control module (3), wherein the one-dimensional DCT module (1) adopts a plurality of butterfly computing units and a plurality of odd coefficient processing units for completing each DCT in the HEVC standards, the odd coefficient processing units resolve the complicated multiply operation into multistage circuits and adopt a shifter, an adding device and a subtracter, i.e. the multistage shifter, the adding device and the subtracter are used for replacing a matrix multiplier, and the circuit structure is simplified. The transition coder has the advantages that the structure is simple and regular, the reusability is high, the key route is short, the lock frequency is high, and the integration is easy. The transition coding on video residual data is efficiently realized under the condition of not using the multipliers.

The invention discloses a compatibility capturing method of a multi-mode GNSS (Global Navigation Satellite System) combination receiver. The capturing method comprises the following steps of: carrying out corresponding capture process on a satellite signal within coherent integration accumulation time and non-coherent integration accumulation time; adopting a fuzzy logic algorithm in the capture process, dynamically adjusting the coherent integration accumulation time and the non-coherent integration accumulation times according to a carrier-to-noise ratio and a carrier speed; and within the coherent integration accumulation time, carrying out the secondary sampling on a middle frequency signal of the acquired satellite signal, i.e. all data are decomposed into a plurality of groups, and the data points in each group are at one pseudo-random code element, and subsequently the Fourier transform, the Fourier inversion, the DCT (Discrete Cosine Transformation), the IDCT (Inverse Discrete Cosine Transform), the mode value square and threshold judgment process are carried out. With the adoption of the capturing method, the defects that signals cannot be captured as an existing capturing method is low in sensitivity and likely to be interfered are overcome, and satellite signals can be captured normally when a GNSS signal is shielded and strong environment noise exists.