The Discrete Haar wavelet Transform has a wide range of applications from signalprocessing to video and imageprocessing. Data-intensive structure and easy of implementation make Discrete Haar wavelet Transform conve...
详细信息
ISBN:
(纸本)9781467379120
The Discrete Haar wavelet Transform has a wide range of applications from signalprocessing to video and imageprocessing. Data-intensive structure and easy of implementation make Discrete Haar wavelet Transform convenient to distribute fundamental operations to multi-CPU and multi-GPU systems. In this paper, the wavelet transform was ported in a compute-efficient way to CPU cluster and programmable GPU cluster by utilizing MPI and CUDA respectively. Experimental studies conducted as part of the parallelization strategies for two-dimensional Discrete Haar wavelet Transform show that the total running time required to process all rows and columns of an image with different size is significantly decreased on the GPU cluster when compared to the its counterparts on a single CPU, single GPU and CPU cluster. Besides the speedup of the GPU based transform, preliminary analysis also showed that the size of the image is an important parameter on the scalability of the GPU cluster.
This papers deals with an efficient image compression technique for images having low dynamic range. The images with low dynamic range generally have low intensity variations. By considering this fundamental character...
详细信息
ISBN:
(纸本)9781467382199
This papers deals with an efficient image compression technique for images having low dynamic range. The images with low dynamic range generally have low intensity variations. By considering this fundamental characteristic into account we can go for image compression at higher ratio with small modifications to the existing block based EZW algorithm. To achieve the improvement in compression ratio, block-wise Embedded Zero wavelet (EZW) is applied on the images by forcing all the blocks in the image to take the same number of dominant and sub-ordinate passes. The number of passes applied on each block of the image will be equal to the lowest number of passes taken by one of the blocks in image. This downside the number of passes applied on the image which reduces the number of bits used for encoding the image which successively increase the compression ratio. The proposed algorithm is analyzed with respect to the normal block-wise EZW by mathematical parameters as well as with visual quality. The mathematical parameters chosen for comparison are Peak signal-to-Noise Ratio (PSNR) and Structural Similarity (SSIM) index. The algorithm is tested from low resolution to UHD resolution images.
A transform that estimates the first and higher-order derivatives of images at multiple scales is proposed. The proposed transform, called Multi-Scale Derivative Transform (MSDT), is specially designed for image water...
详细信息
A transform that estimates the first and higher-order derivatives of images at multiple scales is proposed. The proposed transform, called Multi-Scale Derivative Transform (MSDT), is specially designed for image watermarking applications. To calculate the first and higher-order image derivatives, MSDT uses the detail wavelet coefficients of the image. Unlike traditional wavelet-based image derivative estimators that use only the horizontal and vertical wavelet coefficients, the proposed transform maps the diagonal as well as the horizontal and vertical wavelet coefficients to the horizontal and vertical derivatives of the image. The inverse transform is designed such that any change in the image derivative domain results in the minimum possible change in the wavelet coefficients. This renders a watermark, that is embedded in the derivative domain, less visible in the image domain. The application of this transform to image watermarking is discussed, and the results are compared with those obtained using traditional wavelet-based image derivative estimators. (C) 2014 Elsevier Inc. All rights reserved.
EEG signals collected non-invasively from the cerebral cortex are often contaminated with signals from eye movement [EOG], which considerably degrades the reliability of extracting proper information from the actual s...
详细信息
ISBN:
(纸本)9781479989973
EEG signals collected non-invasively from the cerebral cortex are often contaminated with signals from eye movement [EOG], which considerably degrades the reliability of extracting proper information from the actual signals. This study attempts a two-step algorithm to obtain an EOG artifact free EEG signal with best performance index. Two types of decomposing methods namely Discrete wavelet Transform (DWT) and Empirical Mode Decomposition (EMD) were used initially to decompose the contaminated signal The resultant signal further undergoes two processes each;first by Canonical Correlation analysis (CCA) technique and the second one by reduced frequency components using threshold level to identify the unwanted frequency components (TH.-FFT). The output signal from each of these two processes are reconstructed to obtain a clean signal Comparison between the reconstructed cleaned signals and the contaminated EEG signal reveal that the reconstructed signal is cleaner when (CCA) technique was used as compared with that of (TH.-FFT). Thus the performance indexes of this experiment for the two methods, measured with RMSD and SDR, indicated that combined DWT, EMD and CCA method outperforms the combined DWT, EMD and TH.-FFT method in elimination of eye movement contamination from EEG signal. The present algorithm gave better performance results compared to other existing methods and hence would be better suited for various offline analyses involving the low frequency bands of EEG signals.
B-splines caught interest of many engineering applications due to their merits of being flexible and provide a large degree of differentiability and cost/quality trade-off relationship. However, they have less impact ...
详细信息
B-splines caught interest of many engineering applications due to their merits of being flexible and provide a large degree of differentiability and cost/quality trade-off relationship. However, they have less impact with continuous-time applications as they are constructed from piecewise polynomials. On the other hand, exponential spline polynomials (E-splines) represent the best smooth transition between continuous and discrete domains as they are made of exponential segments. In this paper, we present a complete analysis for an E-spline-based subband coding (wavelet) perfect reconstruction (PR) system. Derivations for the scaling and wavelet functions are presented, along with application of the proposed system in image compression and image denoising. In image compression, a comparison of the proposed technique compared with the B-spline-based PR system as well as the basic wavelet subband system with the SPIHT image codec is presented. In image denoising, we report the enhancement achieved with the proposed E-spline-based denoising approach compared with B-spline-based denoising and another basic denoising technique. In both applications, E-splines show superior performance as will be illustrated.
Breast cancer is one of the most deadly diseases for women. Mammogram is very important imaging technique used diagnosis in early stages of breast cancer. In this study, a decision support system which helps experts t...
详细信息
Breast cancer is one of the most deadly diseases for women. Mammogram is very important imaging technique used diagnosis in early stages of breast cancer. In this study, a decision support system which helps experts to examine mammogram images in the fight against breast cancer is developed. In this study, firstly several preprocesses are applied to mammogram to make image clear and segmentation of mass is provided with an appropriate threshold value. After the segmentation processes, features of the tumor mass are obtained. The obtained features are classified as normal, benign or malignant using kNN (k-nearest neighbours) classifiers. In this study, its have been were shown that, effect of kurtosis, skewness and wavelet energy features on classification performance is shown. As a result, it has been seen that, these features improve the classification performance.
This study explores the use of the graphics processing units (GPUs) for performing the two-dimensional discrete wavelet transform (DWT) of images. The study of fast wavelet transforms has been driven both by the enorm...
详细信息
This study explores the use of the graphics processing units (GPUs) for performing the two-dimensional discrete wavelet transform (DWT) of images. The study of fast wavelet transforms has been driven both by the enormous volumes of data produced by modern cameras and by the need for real-time processing of these data. With the emergence of general computing on GPUs, many time-consuming applications have started to reap the associated benefits. In the implementation of a GPU-based DWT, two approaches are used according to the published works, which are the row-column (RC) approach and the block-based (BB) approach. Most state-of-the-art techniques are based on the RC approach, which utilises the parallelism between different rows and columns;few works are based on the BB approach, which explores the parallelism between different blocks of the image. Although easy to implement, resource usage of the RC approach is usually related to the image size. Another shortcoming of the RC approach lies in the fact, according to the author's analysis, that more global memory access is required. The authors thus select the BB approach in this study. Experiment results show that the proposed BB approach outperforms the RC approach, being 99x faster than a native CPU implementation for 4096 x 4096 images.
基于分块的压缩感知算法适用于图像信号的处理,通过平滑迭代阈值投影法可以快速重构图像,但存在低采样率下重构图像质量较差的缺点。基于全变差分的分块压缩感知算法,在一定程度上能提升重构效果,但降低了运算速度。针对以上算法的不足,提出基于多尺度的自适应采样图像分块压缩感知算法。根据小波分解后不同层对重构结果影响所占权重不同的特性,自适应分配给每一层不同的采样率,并在重构时将平滑迭代阈值投影法应用到每一层的每一个子带的分块上。实验结果表明,与传统的迭代阈值投影法相比在重构质量上提高了1~3 d B,在重构速度上与迭代阈值投影法相当并优于全变差分法。
The protection of data is of at prime urgency in the medical field to boost the telemedicine applications. There is a need of robust and secure mechanism to transfer the medical images over the Internet. The proposed ...
详细信息
The protection of data is of at prime urgency in the medical field to boost the telemedicine applications. There is a need of robust and secure mechanism to transfer the medical images over the Internet. The proposed watermarking method is based on two popular transform domain techniques, discrete wavelet transforms (DWT) and discrete cosine transform (DCT). In the embedding process, the cover medical image is divided into two separate parts, region of interest (ROI) and non region of interest (NROI). For the identity authentication purpose, multiple watermarks in the form of image and text are embedding into ROI and NROI part of the same cover media object respectively. In order to enhance the security of the text watermark, Rivest-Shamir-Adleman (RSA) encryption technique is applied to the text watermark before embedding and the encrypted EPR data is embedded into the NROI portion of the cover medical image. The performance of the proposed method is evaluated for signalprocessing attacks and the desired outcome is obtained without significant degradation in extracted watermark and perceptual quality of the watermarked image.
Currently, the wavelet transform is widely used in the signalprocessing domain, especially in the image compression because of its excellent de-correlation property and the redundancy property included in the wavelet...
详细信息
Currently, the wavelet transform is widely used in the signalprocessing domain, especially in the image compression because of its excellent de-correlation property and the redundancy property included in the wavelet coefficients. This paper investigates the redundancy relationships between any two or three components of the wavelet coefficients, the wavelet bases and the original signal. We discuss those contents for every condition according to the continuous form and the discrete form, respectively, by which we also derive a uniform formula which illuminates the inherent connection among the redundancy of the wavelet coefficients, the wavelet bases and the original signals. Finally, we present the application of the wavelet coefficient redundancy property in the still image compression domain and compare the properties of the Discrete wavelet Transform (DWT) with that of the Discrete Cosine Transform (DCT).
暂无评论