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Сжатие видео - Denoising

Английские материалы
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Riccardo Bernardini and Guido M. Cortelazzo A Post-Processing Technique for Noise Removal of Range Data
Abstract—Spurious range data pose a serious visualization problem with active light systems, as they can totally deform the acquired 3-D shapes. This work presents a technique for their detection based on geometrical considerations. The proposed method does not need extra hardware and can be used effectively as post-processing noise removal provision. The method has been extensively tested on real data. Its performance is discussed and demonstrated by examples.
RAR  766 кбайт
Jeonghun Yang, Hyuk Choi, and Taejeong Kim Noise Estimation for Blocking Artifacts Reduction in DCT Coded Images
Abstract—This paper proposes a postprocessing algorithm that can reduce the blocking artifacts in discrete cosine transform (DCT) coded images. To analyze blocking artifacts as noise components residing across two neighboring blocks, we use 1-D pixel vectors made of pixel rows or columns across two neighboring blocks. We model the blocky noise1 in each pixel vector as a shape vector weighted by the boundary discontinuity. Boundary discontinuity of each vector is estimated from the difference between the pixel gradient across the block boundary and that of the internal pixels. We make minimum mean squared error (MMSE) estimates of the shape vectors, indexed by the local image activity, based on the noise statistics prior to postprocessing. Once the estimated shape vectors are stored in the decoder, the proposed algorithm eliminates the noise components by simply subtracting from each pixel vector an appropriate shape vector multiplied by the boundary discontinuity. The experimental results show that the proposed algorithm is highly effective in reducing blocking artifacts in both subjective and objective viewpoints, at low computational burden.
RAR  1222 кбайт
John F. Arnold, Michael R. Frater, and Yaqiang Wang Efficient Drift-Free Signal-to-Noise Ratio Scalability
Abstract—Signal-to-noise ratio (SNR) scalability has been incorporated into the MPEG–2 video-coding standard to allow for the delivery of two services with the same spatial and temporal resolution but different levels of quality. In this paper, we begin by reviewing the performance of a single-loop SNR scalable encoder that is compliant with the MPEG–2 standard and demonstrate that its performance is limited by drift in the base layer. We also look at an alternative single-loop drift-free noncompliant SNR scalable encoder, but discover that its coding efficiency is poor.We then review the performance of an MPEG-compliant two-loop SNR scalable encoder. Finally, we propose a new two-loop noncompliant encoder which achieves improved coding performance at the expense of some increase in encoder and decoder complexity.
RAR  279 кбайт
Chang-Su Kim, Rin-Chul Kim, Member, and Sang-Uk Lee Robust Transmission of Video Sequence over Noisy Channel Using Parity-Check Motion Vector
Abstract—The motion compensation-discrete cosine transform (MC-DCT) coding is an efficient compression technique for digital video sequence. However, the compressed video signal is vulnerable to transmission errors over noisy channel. In this paper, we introduce a novel concept of parity-check motion vector (PMV) into the MC-DCT coder in order to improve its error robustness. By inserting the redundant PMV’s systematically into the compressed bitstream, the proposed algorithm is capable of recovering very severe transmission errors, such as loss of an entire frame, in addition to detecting the errors effectively without requesting any information from external devices. The proposed algorithm is implemented based on the H.263 coder, and tested intensively in a realistic error prone environment. It is shown that the proposed algorithm provides much better objective and subjective performances than the conventional H.263 coder in the error prone environment.
RAR  544 кбайт
Chang Wen Chen and Zhaohui Sun Image Transmission over Noisy Channels with Variable-Coefficient Fixed-Length Coding Scheme
Abstract— A variable-coefficient fixed-length coding scheme is proposed for wavelet-based image transmission over noisy channels. Multiple subband coefficients are grouped into an extended source symbol and coded as a fixed-length code word such that the extended source symbols have almost the same probabilities. Part of the codebook is fixed based on the observation of the coefficient spatial distribution patterns in each subband to alleviate the transmission of the codebook. The remaining code positions within the fixed-length codebook can be utilized to combat channel errors by carefully arranging the code positions or be filled with other frequently appearing coefficient sequences to achieve higher compression ratio.
RAR  152 кбайт
Jong-Ki Han and Hyung-Myung Kim Classified VQ Codebook Index Assignment for Communication over Noisy Channels
Abstract—In this paper, an improved index assignment procedure is proposed to reduce the channel error effect in a communication system employing classified vector quantization (CVQ). The proposed algorithm consists of two parts: inner index assignment (IIA) and cross index assignment (CIA). The IIA reduces the distortion resulting from the error in order bits, presenting the identity of each code vector in a subcodebook. The CIA modifies the indexes assigned by the IIA in such a way that the effect of the channel error occurring in class bits, indicating the class information of the code vector, can be minimized. Simulation results show that the proposed algorithms enable a reliable communication over noisy channels even without employing the channel encoding.
RAR  312 кбайт
G. de Haan, T.G. Kwaaitaal-Spassova, M. Larragy and A.O. Ojo SINGLE-CHIP TV NOISE REDUCTION
This new noise reduction IC for consumer TV1 automatically adapts to the noise level, and achieves 3 dB improvement when used stand-alone. It doubles the gain of current NR designs when cascaded.
RAR  229 кбайт
R. J. Schutten, G. de Haan and A. H. M. van Roermund†. Noise filtering for television receivers with reduced memory
Television receivers are often used in places with sub-optimal reception conditions, therefore noise reduction is becoming a more popular feature. To include noise reduction in low-end TV receivers, low-cost noise reduction filters are desired. The paper describes a concept to generally reduce the memory capacity required by a recursive noise filter. This is achieved by subsampling. The principle of subsampling is tested on a previously developed 2-D spatial noise filter.
RAR  227 кбайт
G. de Haan, T.G. Kwaaitaal-Spassova, M.M. Larragy, and O.A. Ojo. TELEVISION NOISE REDUCTION IC
A noise reduction IC1 for consumer television has been designed. The IC contains a spatial filter for Gaussian noise and a temporal filter for clamp noise. Both filters automatically adapt to the noise level.
RAR  68 кбайт
G. de Haan, T.G. Kwaaitaal-Spassova, M.M. Larragy, O.A. Ojo, and R.J. Schutten. TELEVISION NOISE REDUCTION IC
A noise reduction IC1 for consumer television has been designed. The IC contains a spatial filter for Gaussian noise and a temporal filter for clamp noise. To reduce clamp noise, the average value of the pixels in a linesegment are filtered rather than individual pixels. This reduces the cost of the temporal filter significantly, enabling the use of embedded memory. Analog interfaces are provided, as well as a line-locked clock generator. The chip includes a noise level estimator for optimal filtering under varying reception conditions. The average gain of the spatial filter is around 3 dB, whereas the temporal filter yields up to 8 dB improvement on clamp noise.
RAR  448 кбайт
Gustav Tolt Image noise reduction based on fuzzy similarity
Reducing noise is one of the most basic image processing operations.We propose a non-linear fuzzy filter structure that efficiently deals with a mixture of these kinds of noise and is suitable for real-time realization using an FPGA (Field Programmable Gate Array) device. The filter contains two tunable parameters, and it seems to be fairly robust to changes in noise distribution. The main advantage of the filtering structure is its suitability for implementation on hardware. So far, the operation of the FSB filters has only been simulated, but the flexible filter structure is believed to be suitable for high-speed performance, as simple FSB filters have be estimated to operate at about 50 frames per second for 1024.1024 pixels images.
RAR  111 кбайт
J.G. Puttenstein, I. Heynderickx and G. de Haan, Objective evaluation of noise reduction performance in TV-systems
RAR  178 кбайт
RAR  128 кбайт
Passant V. Karunaratne, C. Andrew Segall, and Aggelos K. Katsaggelos A RATE-DISTORTION OPTIMAL VIDEO PRE-PROCESSING ALGORITHM
Pre-processing algorithms improve the quality of a compression system by removing unimportant data before encoding. This enhances both the visual quality and coding efficiency of the system. In this paper, we cast the pre-processing problem in the operational rate-distortion framework. Filtering the displaced frame difference is the focus, and the proposed method couples the choice of the quantization scale to the response of the prefilter. Coding errors are then addressed by penalizing significant differences between coded blocks. Finally, experimental results illustrate the efficacy of the method within the context of an MPEG-2 coding scenario.
RAR  149 кбайт
The purpose of this paper is to introduce a fast automated whitenoise estimation method which gives reliable estimates in images with smooth and textured areas. This method is a block-based method that takes image structure into account and uses a measure other than the variance to determine if a block is homogeneous. It uses no thresholds and automates the way that blockbased methods stop the averaging of block variances. The proposed method selects intensity-homogeneous blocks in an image by rejecting blocks of structure using a new structure analyzer. The analyzer used is based on high-pass operators and special masks for corners to allow implicit detection of structure and to stabilize the homogeneity estimation. For typical image quality (PSNR of 20-40 dB) the proposed method outperforms other methods significantly and the worst-case estimation error is 3 dB which is suitable for real applications such as video surveillance or broadcasts. The method performs well even in images with few smooth areas and in highly noisy images.
RAR  174 кбайт
Abstract — The reduction of gaussian noise is still an important task in video systems. The presented scheme consists mainly of a subband based recursive temporal filter adapted to special properties of the human visual system. This filter is supported by a spatial filter with low hardware expense, which consists of an image analysing highpass filter bank and an adaptive lowpass FIR-filter for noise reduction.
RAR  122 кбайт
Richard Alan Peters II A New Algorithm for Image Noise Reduction using Mathematical Morphology
Morphological openings and closings are useful for the smoothing of grayscale images. However, their use for image noise reduction is limited by their tendency to remove important, thin features from an image along with the noise. This paper is a description and analysis of a new morphological image cleaning algorithm (MIC) that preserves thin features while removing noise. MIC is useful for grayscale images corrupted by dense, low-amplitude, random or patterned noise. Such noise is typical of scanned or still-video images. MIC di?ers from previous morphological noise ?lters in that it manipulates residual images – the di?erences between the original image and morphologically smoothed versions. It calculates residuals on a number of di?erent scales via a morphological size distribution. It discards regions in the various residuals that it judges to contain noise. MIC creates a cleaned image by recombining the processed residual images with a smoothed version. This paper describes the MIC algorithm in detail, discusses the e?ects of parametric variations, presents the results of a noise analysis and shows a number of examples of its use, including the removal of scanner noise. The paper also demonstrates that MIC signi?cantly improves the JPEG compression of a grayscale image.
RAR  1934 кбайт
Hakan Norell, Bengt Oelmann and Youshi Xu Spatio-Temporal Noise Reduction ASIC for Real-Time Video Processing
This paper presents the improved design of a device for real-time noise reduction in digitized video using temporal filter techniques targeting ASIC implementation. The noise reduction device is a three dimensional filter using both spatial and temporal information from the video sequence that is to be filtered. The input format of the video stream is uncompressed RGB and the filter is accessing seven image frames at a time. We can show that a significant improvement, upto 17%, can be achieved with the refined algorithm. This is due to the refined handling of salt-pepper noise. The improvements have been made without increasing the implementation cost in terms of area and timing. The solution we propose in this paper has a chip area of 19.5 mm2, 96 I/O-signals, 71 MHz I/O frequency for real-time filtering in a 0.6 mm CMOS process and standard cell implementation approach.
RAR  134 кбайт
Synthetic aperture radar (SAR) imaging systems generate vast quantities of data and hence efficient image compression is an essential step for reducing the cost of data storage and transmission. The compression performance achieved by wavelets based on linear filters is limited by the presence of speckle noise. In this paper a new compression scheme for SAR images that uses a nonlinear wavelet decomposition is proposed. Using the lifting framework, a 4-band filter bank and nonlinear filters are used to separate the underlying image features from the speckle noise. Experimental results show a compression performance that is much improved in comparison with JPEG.
RAR  243 кбайт
M. Necker, F. Sanzi, J. Speidel An Adaptive Wiener-Filter for Improved Channel Estimation in mobile OFDM-Systems
Abstract—In this paper we propose an improved channel estimator for a pilot based, mobile OFDM-system by adaptive Wiener-filtering in the frequency direction. In order to achieve a better estimation, the conventional fixedWiener-Filter is replaced by an adaptive filter which adapts to the actual channel characteristic. The primary effect is a bandwidth reduction which minimizes the impact of noise onto the channel estimate.
RAR  126 кбайт
The classical solution to the noise removal problem is the Wiener lter, which utilizes the second-order statis- tics of the Fourier decomposition. Subband decomposi- tions of natural images have signi cantly non-Gaussian higher-order point statistics; these statistics capture im- age properties that elude Fourier-based techniques. We develop a Bayesian estimator that is a natural exten- sion of the Wiener solution, and that exploits these higher-order statistics. The resulting nonlinear esti- mator performs a \coring" operation. We provide a simple model for the subband statistics, and use it to develop a semi-blind noise-removal algorithm based on a steerable wavelet pyramid.
RAR  143 кбайт
This paper presents a new method for suppressing noise in video sequences. The filter is an extension of the k-means nearest neighbor filter for still image noise removal. To show the feasibility of the filter we compare it to the rational filter and the ?-trimmed mean filter. It is shown to outperform both filters from a visual quality point of view.
RAR  171 кбайт
Abstract — The reduction of gaussian noise is still an important task in video systems. For this purpose a spatio-temporal noise reduction scheme for interlaced video is presented in this paper. It consists mainly of a subband based temporal recursive filter which makes use of some special properties of the human visual system. This temporal system is supported by a preceding detail preserving spatial filter with low hardware expense, which consists of an image analysing highpass filter bank and an adaptive lowpass FIR-filter for noise reduction. Both the spatial and temporal noise reduction have been evaluated with a large amount of simulations which result in a very good objective and subjective efficiency. Furthermore the chain of both temporal and spatial noise reduction may even yield results which are better than the sum of pure spatial and temporal techniques.
RAR  883 кбайт

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