187 results about "Recursive filter" patented technology

A method of filtering to remove coding artifacts introduced at block edges in a block-based video coder, the method having the steps of: checking the content activity on every line of samples belonging to a boundary to be filtered and where content activity is based on a set of adaptively selected thresholds determined using Variable-Shift Table Indexing (VSTI); determining whether the filtering process will modify the sample values on that particular line based on said content activity, and selecting a filtering mode between at least two filtering modes to apply on a block boundary basis, implying that there would be no switching between the two primary modes on a line by line basis along a given block boundary. The two filtering modes include a default mode based on a non-recursive filter, and a strong filtering mode which features two strong filtering sub-modes and a new selection criterion that is one-sided with respect to the block boundary to determine which of the two strong filtering sub-modes to use. The two strong filtering sub-modes include a new 3-tap filter sub-mode and a 5-tap filter sub-mode that permits a more efficient implementation of the filter.

An interlace-to-progressive scan conversion system comprises: a spatial line averaging prefilter; a motion estimator; a three-stage adaptive recursive filter. The motion estimator comprises: a 3-D recursive search sub-component having a bilinear interpolator; a motion correction sub-component having an error-function including penalties related to the difference between a given candidate vector and a plurality of neighboring vectors; a block erosion sub-component. The motion estimator assumes that motion is constant between fields. The three-stage adaptive recursive filter comprises: a first stage that selects between using static pixels data and moving pixels data from a next field; a second stage that selects a more valid set of data between motion compensated data from a previous field and the pixels selected by the first stage; a third stage that combines an intra-field interpolation with the more valid set of data selected by the second stage.

The present invention relates to improved multiple access communications. In one form, the invention relates to an improved signal processing method and apparatus for an iterative method of determining the reception of a signal in a multi user packet based wireless OFDM (Orthogonal Frequency Division Multiplexing) communication system. In other forms the present invention provides recursive filtering for joint iterative decoding in a variety of systems and functions such as linear multiple access channel decoders, iterative equalisation, iterative joint channel estimation and detection / decoding, iterative space-time processing, iterative multi user interference cancellation and iterative demodulation. In one particular form the present invention provides an iterative decoding circuit for a wireless multiuser communications receiver comprising a first signal processing means for receiving at least one received signal, said first signal processing means comprising at least two linear iterative filters such that the first linear iterative filter provides an estimate of a selected received signal to an estimated signal output and a second linear iterative filter provides estimates of at least one other received signal, delayed by one iteration cycle, to an input of said first linear iterative filter, a second signal processing means for receiving the estimated signal output of the first linear iterative filter and providing a further received signal estimate to the input of the first signal processing means in a succeeding iteration cycle of the decoding circuit.

The present application relates to tracking a position of a device, e.g. for detecting slow and rapid earth deformation, by making use of a recursive filter having the filter characteristic adapted to a detected type of motion. If the motion of the position tracking device is rapid, the filter characteristic is set such that the rapid motion can be tracked with the necessary speed. On the other hand, if the motion is slow, e.g. during times of a normal tectonic drift, the filter characteristic is set such that the motion is slowly tracked with the advantage of efficient noise reduction, i.e. noise in the input signal is effectively barred and does not pass through the filter to the output signal. Thus, in times of rapid motion the convergence speed of the filter output signal to the input signal is set high for fast convergence and in times of slow motion the convergence speed of the filter output signal to the input signal is set low for a slow convergence. The filter may be a Kalman filter.

An integrated circuit, e.g. an Audio Codec (AC) '97 conforming audio codec, includes a digital filter and gain module including multiple channels of gain control and multiple channels of digital filtering. A gain control module includes an overflow check of data samples requiring differing lengths of clamping. Each channel of the digital filter includes a finite impulse response (FIR) filter, and an infinite impulse response (IIR) filter. The digital filtering is implemented largely in hardware independent of the number of channels required and / or independent of the required order of the filtering. Thus, filter channels can be added or additional filtering implemented merely by increasing the clock speed without changing the digital filter design. The FIR filter is capable of being reset each frame to prevent a direct current (DC) buildup at internal nodes. The IIR filter performs a plurality of 2nd order biquadratic equations in an overall average of as few as four clock cycles per 2nd order biquad. A random access memory (RAM) is used to store the state variables for the 2nd order biquadratic equations. The state variable RAM is reset by controlling the clear input of latches at an input and / or the output of the state variable RAM, and the state variable RAM is addressed by a delta counter which is independent of the particular number of filter channels or filter orders implemented. Test patterns may be inserted between functional blocks of an integrated circuit such as the disclosed audio codec by appropriate control of the preset and clear inputs to output latches of the functional blocks.

A method of filtering to remove coding artifacts introduced at block edges in a block-based video coder, the method having the steps of: checking the content activity on every line of samples belonging to a boundary to be filtered and where content activity is based on a set of adaptively selected thresholds determined using Variable-Shift Table Indexing (VSTI); determining whether the filtering process will modify the sample values on that particular line based on said content activity; and selecting a filtering mode between at least two filtering modes to apply on a block boundary basis, implying that there would be no switching between the two primary modes on a line by line basis along a given block boundary. The two filtering modes include a default mode based on a non-recursive filter, and a strong filtering mode which features two strong filtering sub-modes and a new selection criterion that is one-sided with respect to the block boundary to determine which of the two strong filtering sub-modes to use. The two strong filtering sub-modes include a new 3-tap filter sub-mode and a 5-tap filter sub-mode that permits a more efficient implementation of the filter.

A method and structure for adjusting the contrast of a digital image includes inputting an image, dividing the image into a pedestal signal and a texture signal, applying a tone scale function to the pedestal signal to produce a modified pedestal signal, and adding the texture signal to the modified pedestal signal to produce a processed digital image channel. The dividing filters a pixel of the image using weighting that is dependent upon coefficients of neighboring pixels adjacent the pixel. The filtering blurs the pedestal signal such that flat areas of the image are blurred more that discontinuities in the image.

A method of processing an image includes traversing pixels of an image in a single pass over the image. An inverting function is applied to the pixels. A recursive filter is applied to the inverted pixel values. The filter has parameters which are derived from previously traversed pixel values of the image. A pixel value is combined with a filter parameter for the pixel to provide a processed pixel value for a processed image.

The present invention relates to improved multiple access communications. In one form, the invention relates to an improved signal processing method and apparatus for an iterative method of determining the reception of a signal in a multi user packet based wireless OFDM (Orthogonal Frequency Division Multiplexing) communication system. In other forms the present invention provides recursive filtering for joint iterative decoding in a variety of systems and functions such as linear multiple access channel decoders, iterative equalisation, iterative joint channel estimation and detection / decoding, iterative space-time processing, iterative multi user interference cancellation and iterative demodulation. In one particular form the present invention provides an iterative decoding circuit for a wireless multiuser communications receiver comprising a first signal processing means for receiving at least one received signal, said first signal processing means comprising at least two linear iterative filters such that the first linear iterative filter provides an estimate of a selected received signal to an estimated signal output and a second linear iterative filter provides estimates of at least one other received signal, delayed by one iteration cycle, to an input of said first linear iterative filter, a second signal processing means for receiving the estimated signal output of the first linear iterative filter and providing a further received signal estimate to the input of the first signal processing means in a succeeding iteration cycle of the decoding circuit.

The invention relates to the digital image processing technology, and provides a multi-exposure image fusion method with rapid and effective calculation. The method does not need complex image decomposition and reconstruction processes, the fusion is accomplished via a pixel weighting manner, more detailed information is displayed by the images, and the image quality is improved. According to the technical scheme of the high-dynamic-range image fusion method based on gradient and brightness information, the method comprises following steps: 1) calculating the local contrast weighting factor Li (x, y) of each inputted multi-exposure image; 2) converting an original image to a color space with the hue H, the saturation S, and the brightness I, extracting the brightness component I, and calculating the brightness weighting factor Hi (x, y); 3) estimating weight; 4) improving a weighted image by the adoption of a recursive filter and obtaining the final weighting function of each inputted image; and 5) performing weighted fusion of the multi-exposure images. The method is mainly applied to digital image processing.

A motion estimation process in video coding takes into account the estimates in the immediate spatio-temporal neighborhood, through an adaptive filtering mechanism, in order to produce a smooth and coherent optical flow field at each pixel position. The adaptive filtering mechanism includes a recursive LMS filter based on pixel-wise algorithm for obtaining motion vectors in a reference image of a video image frame, while consecutively scanning through individual pixels of the image frame. This motion estimation process is particularly well suited for the estimation of small displacements within consecutive video frames, and can be applied in several applications such as super-resolution, stabilization, denoising of video sequences. The method is also well suited for high frame rate video capture.

The invention provides a real-time medical video image denoising method, which is applied to medical video image sequences which are acquired in real time or stored and performs time-space domain recursive filtering treatment of each frame of video image by using the high degree of correlation of two adjacent images, wherein the size of a filter window can be adaptively adjusted according to a noise level. In the invention, a time-domain motion compensating method and a space-domain denoising enhancement algorithm are combined, a movement area, a noise area and a background area are detected by applying a motion compensating method and a morphological operator according to the current pixels of the images, and the overall noise levels of the images are estimated in the noise area.

Noise reduction is an important feature in consumer television. This is realized by spatial, temporal or spatio-temporal filters. Spatial filters require pixels from within one image, while temporal filters require samples from two or more successive images. The spatio-temporal filter unit (100) integrates spatial and implicit motion-compensated temporal noise reduction in one filter. For the motion compensation, no motion vectors are required. The spatio-temporal filter unit (100) is provided with a sigma filter (112) having one filter kernel (107) designed to operate on the pixels from both a current image and from the output of the spatio-temporal filter unit, being a temporally recursive filtered image. The operation of the spatio-temporal filter unit (100) can be adjusted by varying the thresholds of the sigma filter (112) and the selection of pixels. The adjustments can be controlled by a motion estimator (222), a motion detector (224) and a noise estimator (220).

A robust recursive operator for fast implementation of the computationally intensive module of Retinex-type image enhancement algorithms. The proposed module includes a cascaded recursive filter. The parameters of the filter are a function of the input signal, and are scale independent. Furthermore, the image is first processed according to an open and close prefilter, followed by application of the cascaded recursive filters. After application of the cascaded recursive filters, a post filter maximum output is applied to the signal. The module will usually be used as a part of a Retinex-type image processing system, which might use it after some preprocessing of an input image, and which will result in a manipulation of the input image and the module's output image.

A method of processing an image includes traversing pixels of an image in a single pass over the image. An inverting function is applied to the pixels. A recursive filter is applied to the inverted pixel values. The filter has parameters which are derived from previously traversed pixel values of the image. A pixel value is combined with a filter parameter for the pixel to provide a processed pixel value for a processed image.

An approach is provided for estimating a channel of a multi-carrier transmission by splitting an interpolation or extrapolation or smoothing of estimates into a frequency domain part and a time domain part, wherein the channel estimation unit is configured to use for both the frequency domain part and the time domain part respective recursive filters, and wherein at least one of the recursive filters is adapted to channel conditions of the multi-carrier transmission.

The invention discloses a method for estimating city expressway traffic states based on mobile detection of smartphones, wherein a city expressway cell transmission model is built firstly, a observing network is built by adopting a smartphone to rapidly detect parameters, then a state space model based on a lighthill-whitham-richards (LWR) traffic flow model is designed, a traffic state and a boundary flux are synchronously estimated by utilizing three-step type recursive filters algorithm, then are coalesced with upstream and downstream subsection boundary flux by adopting a weighted average algorithm, and traffic parameter estimation is upgraded, thereby achieving real-time distributed estimation of city expressway network traffic state. The method for estimating the city expressway traffic states based on the mobile detection of the smartphones can collect average speed information of vehicles on any time and space positions of a loop, enables traffic estimation not to be restrained by the position of a detector, can achieve synchronization estimation of traffic density and boundary flux by designing a state-space model and a three-step recursive filter, and achieves the problem of large range expressway network traffic estimation by being coalesced with subsection boundary flux, reduces model order, and improves efficiency of algorithm.

Certain embodiments of the present invention provide a system and method for reducing image noise with the use of a minimal error spatiotemporal recursive filter. An input image is filtered both temporally and spatially, producing a temporal output and a spatial output. Both the temporal output and the spatial output are correlated with the input image to produce a temporal correlation output and a spatial correlation output. The temporal correlation output and the spatial correlation output are mixed to generate a selecting signal. The selecting signal directly or indirectly determines the composition of an output image. The selecting signal may select a portion of the temporal output and a portion of the spatial output to compose an output image. Alternatively, the selecting signal may select either the temporal output or the spatial output to compose an output image.

The invention provides a real-time medical video image denoising method, which is applied to a real-time acquired or stored medical video image sequence. Time-space domain recursive filtering processing is performed on each frame of video image by utilizing high-degree correlation of two adjacent images, and the size of a filter window can be adaptively adjusted according to the noise level. In the method, a time-domain motion compensation method - and a space-domain denoising enhancement algorithm are combined; aimed at the current pixel of the image, the motion compensation method and a morphological operator are applied to detect a motion area, a noise area and a background area, and the overall noise level of the image is estimated in the noise area.

A pixel filter includes an input arranged to receive a sequence of pixels, each pixel having an associated pixel value; a filter module arranged to perform a first recursive filter operation in a first direction through the sequence of pixels so as to form a first filtered pixel value for each pixel, and perform a second recursive filter operation in a second direction through the sequence of pixels so as to form a second filtered pixel value for each pixel, wherein the first and second recursive filter operations form a respective filtered pixel value for a given pixel in dependence on the pixel value at that pixel and the filtered pixel value preceding that pixel in their respective direction of operation, the filtered pixel value of the preceding pixel being scaled by a measure of similarity between data associated with that pixel and its preceding pixel; and filter logic configured to, for each pixel of the sequence, combine the first and second filtered pixel values formed in respect of the pixel by the first and second recursive filter operations so as to generate a filter output for the pixel.

The invention provides a radar target tracking method based on measurement conversion and relates to the field of the radar target tracking. The radar target tracking method mainly comprises three parts, namely the first part of obtaining a mean value and a covariance matrix of measurement conversion errors based on measurement values, the second part of obtaining the mean value and the covariance matrix of the measurement conversion errors based on predicted values in a spherical coordinate system, and obtaining parameters involved in the mean value and the covariance matrix by virtue of nonlinear transformation and Jacobian transformation matrix and by use of a predicted state and a prediction error covariance matrix which are estimated by a filter under a rectangular coordinate system, and the third part of selecting the mean value and the covariance matrix both relatively higher in accuracy from the mean values and the covariance matrices obtained in the first two parts as the final mean value and the final covariance matrix of the measurement conversion errors, carrying out a recursive filtering algorithm and realizing target tracking. In the target tracking, the method is high in tracking accuracy and fixed in operand, capable of better meeting the requirements of real-time processing and high in reliability.

Embodiments of a multicarrier receiver with interference-aware demodulation and methods for channel estimation using recursive filtering in wireless networks are generally described herein. Other embodiments may be described and claimed. In some embodiments, orders of a recursive filter are allocated to track a main channel and one or more interfering channels to generate channel estimates.

An image processing apparatus can perform time-sequential weighting addition processing on a moving image constituted by a plurality of frames includes a filter unit configured to obtain an image by performing recursive filter processing on a frame image that precedes a present target frame, which is one of the plurality of frames constituting the moving image, a coefficient acquisition unit configured to acquire a weighting coefficient for the present target frame based on a noise statistic of a differential image between an image of the present target frame and the image obtained by the filter unit, and an addition unit configured to perform addition processing on the moving image constituted by the plurality of frames based on weighting coefficients acquired by the coefficient acquisition unit.

The invention belongs to the underwater sound direction-finding field and relates to a sound pressure and vibration velocity cross-spectrum method-based vector array port and starboard discrimination method. The method includes the following steps that: step (1) after received sound pressure signals are converted into frequency-domain signals, frequency-domain broadband conventional beamforming processing is carried out on the frequency-domain signals, so that an original spatial spectrum matrix can be obtained, wherein the spatial spectrum matrix is a matrix of an outputted spatial spectrum type; step (2) bidirectional one-order recursive filtering processing is performed on the obtained original spatial spectrum matrix, so that a smoothed spatial spectrum can be obtained; and step (3) according to the smooth spatial spectrum, DT decibels are increased based on the smooth spatial spectrum, so that a threshold for spectral peak screening can be obtained. According to the method of the invention, peak screening is carried out on the spatial spectrum; direction estimation is carried out on signals in a spectral peak range; subtractive suppression is carried out on pseudo peak measurement through comparing an estimated result with a spectral peak position; and therefore, the problem of port-starboard ambiguity under a low signal-to-noise ratio can be solved, and weak target detection under a homogeneous noise background can be improved.

A method and apparatus are provided for filtering banding noise in a signal representative of an image. The method includes detecting, by a banding noise detector, banding noise in a neighborhood of a current pixel of the image, determining, by an adaptive filter weight decision unit, a number of banding steps in the neighborhood of the current pixel, determining, by the adaptive filter weight decision unit, a difference between a current pixel value and a previous output value, selecting, by the adaptive filter weight decision unit, a filter weight based on the number of banding steps, the difference between the current pixel value and the previous output value, and the detected banding noise, and filtering, by a recursive filter, the current pixel value according to the selected filter weight.

A method and apparatus for maintaining a diesel particulate filter (DPF) is provided. A pressure drop across the DPF is measured and an initial estimate of soot loading in the DPF is provided to a recursive filter. Using the recursive filter, the initial estimate of soot loading is updated in view of the measured pressure drop to provide an updated estimate of soot loading in the DPF. Active regeneration of the DPF is triggered when an earliest one of at least one triggering condition occurs, the updated estimate of soot loading reaching a predetermined value being one of the at least one triggering condition.

The invention relates to a filtering selection platform based on image content analysis. The platform comprises a median filter device, a self-adaptive recursive filter device and a wavelet filter device. The median filter device, the self-adaptive recursive filter device and the wavelet filter device are used for carry out median filtering, self-adaptive recursive filtering and wavelet filtering on an infrared image to be processed respectively. According to the invention, the customization of an image filtering type is changed, and the efficiency and the accuracy of image filtering are improved.

The invention provides a method for identifying direct sound in a complex multi-path underwater sound environment, which comprises the steps of: (1) initializing a basic parameter which comprises a large width threshold, a small width threshold, a minimum energy threshold, a concave point compensating threshold and a time delay interval threshold; (2) computing an input signal envelope, wherein a self-adaptive Notch filter is adopted for narrowband filtering and self-adaptive iteration is used for estimating the signal envelope; (3) estimating background noise energy by using a recursive filter; determining an energy threshold by using a self-adaptive threshold and a minimum protective mechanism; (4) detecting energy and adopting a concave point compensating technique; and (5) identifying direct sound, namely judging by using double widths and time intervals. The method can be used for effectively enhancing the identifying rate of a direct sound signal in an environment polluted by reflected sound, effectively removing the interference of sharp pulses in background noise, reducing the detecting thresholds of a processor, and enhancing the universality and the stability.

A feed-forward DC offset canceller for use in wireless systems with direct conversion receiver (DCR) architectures, where the DC offset is estimated from the down-converted signal at the output of the mixer and applied before the signal is applied to the analog baseband section Eliminate bias. A linear digital filter estimates and tracks the DC offset, which is subtracted from the downconverted signal before simulating the baseband input. According to different environments and standard requirements, the response of the filter can be adjusted through its coefficients. Although higher order filters can be used as required, a first order recursive filter is preferred because of its simple and effective structure.