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IEEE International conference on signal and image processing applications (ICSIPA)

作者： Muhammad Shahin Uddin Murat Tahtali Andrew J. Lambert Mark R. Pickering School of Engineering and Information Technology University of New South Wales Canberra Australia

Speckle noise is a major shortcoming of any type of ultrasound imaging. Hence, speckle reduction is vital in providing a better clinical diagnosis. The key objective of any speckle reduction algorithm is to attain a speckle free image, whilst preserving the important anatomical features. In this paper, we introduce a nonlinear multi-scale complex wavelet diffusion based algorithm for speckle reduction and sharp edge preservation of 2D ultrasound images. The proposed method exploits some useful features of the dual tree complex wavelet transform and nonlinear diffusion. Simulated experimental results demonstrate that our proposed algorithm significantly reduces speckle noise while preserving sharp edges without discernible distortions. The proposed approach performs better than the previous existing approaches in both qualitative and quantitative measures.

关键词： Educational institutions Australia image edge detection Size measurement

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image restoration by adaptive wavelet thresholding method

Image restoration by adaptive wavelet thresholding method

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IEEE signal processing and Communications applications (SIU)

作者： Mehmet Can Erdem Ziya Telatar Mustafa Doğan Elektrik ve Elektronik Mühendisliği Bölümü Ankara üniversitesi Ankara Turkey Kontrol ve Otomasyon Mühendisliği Bölümü Doğuş Üniversitesi Istanbul Turkey

image enhancement and restoration methods are essential for many fields like medical imaging and radar imaging systems. In literature, there are many studies and different approaches to image enhancement and restoration methods. In this paper, some noise models are studied and the performances of Wiener filter, median filter, mean filter and a proposed method based on adaptive wavelet thresholding are compared on images degraded by mentioned noise models.

关键词： Adaptation models PSNR image restoration Hidden Markov models Wiener filters

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Reduction in thermal stratification in two phase natural convection in rectangular tanks: CFD simulations and Ply measurements

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CHEMICAL ENGINEERING SCIENCE 2013年 100卷 300-325页

作者： Gandhi, Mayurkumar S. Joshi, Jyeshtharaj B. Nayak, Arun K. Vijayan, Pallippattu K. Inst Chem Technol Dept Chem Engn Bombay 400019 Maharashtra India Homi Bhabha Natl Inst Bombay 400094 Maharashtra India Bhabha Atom Res Ctr Reactor Engn Div Bombay 400085 Maharashtra India

Heat transfer by natural convection in a cavity is encountered in various industrial applications, such as heating and cooling of living spaces, fire in building, solar thermal collector systems, electronic and photovoltaic cooling devices, thermosiphon heat exchangers, passive decay heat removal systems, air condensers, etc. In such systems, the cooler (heavier) fluid naturally moves towards the bottom of the tank while the hotter lighter fluid rises towards the top. These flows result into certain extent of non-uniformity (or stratification) of temperature/concentration depending upon the intensity of flow. We have carried out flow (using particle image velocimetiy) and temperature (using thermocouples) measurements in a rectangular tank (0.8 x 0.6 x 0.6 m(3)) fitted with a central tube (forming the heat transfer surface). In order to reduce the stratification, the effects of various internals have been examined. These include (a) changing the ratio of area (heat transfer) to volume (aspect ratio), which is achieved by insulating the heating tube with the help of teflon, (b) introduction of draft tube concentric to the heat transfer tube, and (c) provision of non-conducting or highly conducting fins attached to the tube at different axial locations. Additionally, computational fluid dynamic (CFD) simulations of these systems were performed using the commercial software FLUENT-6.3. The extent of stratification has been investigated for a wide range of Rayleigh numbers (4.34 x 10(11)<= R alpha <= 2.59 x 10(14)). In addition, the flow information obtained from PIV was analyzed for insights into the dynamics of turbulent flow structures. For this purpose, we have used the signal processing technique of Discrete wavelet Transform (DWT). From the analysis, we were able to estimate the size, velocity and energy distribution of turbulent structures. This detailed knowledge was employed in surface renewal type of theories for the estimation of rates of heat transfer. A goo

关键词： Thermal stratification Pool boiling Particle image Velocimetry (PIV) Draft tube Stratification Mixing

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Noise removal using double-density dual-tree complex DWT

Noise removal using double-density dual-tree complex DWT

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International conference on image Information processing

作者： Rahul K. Sarawale S. R. Chougule Dept. of Electronics and Telecomm Bharati Vidyapeeth's College of Engg. Kolhapur India Bharati Vidyapeeth's College of Engg. Kolhapur India

The real world signals do not exist without noise. image denoising system should remove this noise to recover the original signal. Noise removal can be conducted in the time-space (original signal) domain or in a transform domain. To perform in transform domain, researchers utilize the Fourier Transform (FT) or the wavelet Transform (WT). The wavelet Transform, specifically Discrete wavelet Transform (DWT) performs well in noise removal applications. But they suffer from poor directional selectivity, shift sensitivity problem and absence of phase information. The proposed double-density dual-tree complex DWT is based on two scaling function and four distinct wavelets. This technique removes the demerits of the DWT and performs superior in image denoising applications than traditional linear processing (such as wiener filtering), stationary wavelet transform (SWT), dual-tree DWT, double-density DWT etc. In this paper, the prominent results in terms of PSNR, MSE and Histogram of the proposed system are compared with dual-tree complex wavelet transform and global thresholding method. From experimental point of view, the grayscale images are considered which are corrupted by Gaussian noise.

关键词： Discrete wavelet transforms PSNR Filter banks Noise measurement

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Palmprint recognition using Gabor wavelet transform

Palmprint recognition using Gabor wavelet transform

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IEEE signal processing and Communications applications (SIU)

作者： Abidin Çalışkan Burhan Ergen Bilgisayar Mühendisliği Bölümü Batman Üniversitesi Batman Turkey Bilgisayar Mühendisliği Bölümü FIRAT Üniversitesi Elazig Turkey

Palmprint recognition system is regarded as the reliable and accurate biometric identification system available. Viewed in the palmprint recognition system of biometric approaches, compared to other models because it is a new handheld biometric feature recognition system has recently attracted the attention of researchers. In this study, palmprint recognition system based on Gabor wavelet transform has been developed. Firstly, image coordinate system is defined to facilitate image alignment for feature extraction. Then, region of interest is cropped from the palmprint images. With developed system feature extracted of region of interest and given of Multi layer perception classifier.

关键词： Feature extraction wavelet transforms Pattern matching conferences Neural networks

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A hybrid wavelet-spatial denoising filter

A hybrid wavelet-spatial denoising filter

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International conference on Digital signal processing (DSP)

作者： Adib Akl Charles Yaacoub Faculty of Engineering Holy-Spirit University of Kaslik Jounieh Lebanon

Noise is one of the most widespread problems present in nearly all imaging applications. The search for efficient image denoising methods is still a valid challenge. In spite of the sophistication of the recently proposed methods, most algorithms have not yet attained a desirable level of applicability. They all show an outstanding performance when the image model corresponds to the algorithm assumptions, but fail in general and create artifacts or remove fine image structures. Therefore, a universal “best” filter has yet to be found. wavelet analysis is a new method consisting of a set basis functions that can be used to analyze signals in both time (or space) and frequency domains simultaneously. In this paper, a novel hybrid filter for image despeckling that combines wavelet denoising and an enhanced adaptive Kuan filter is proposed, resulting in a significant gain with respect to many spatial as well as wavelet-based speckle reduction filters.

关键词： Approximation methods Noise Smoothing methods Speckle Noise reduction Filter banks

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A new robust and fragile watermarking scheme for images captured by mobile phone cameras

A new robust and fragile watermarking scheme for images capt...

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International conference on Communications, signal processing, and their applications (ICCSPA)

作者： Taha Jassim Raed Abd-Alhameed Hussain Al-Ahmad School of Engineering University of Bradford UK ECE Department Khalifa University of Science Technology and Research UAE

This paper deals with a watermarking scheme for images captured by mobile phone cameras. The new scheme embeds two watermarks in the images for authentication checking and copyright protection. The mobile phone number including the international code is used as the first robust watermark. The number is embedded using the discrete wavelet transform. Hash code of the image is used as a fragile watermark and inserted in the spatial domain. The scheme is blind and does not require the original image in order to extract the watermarks. The fragile watermark is very sensitive to any kind of attacks or image manipulations. On the other hand, the robust watermark causes minimal distortion to the host images. The robustness of the proposed algorithm has been tested against several attacks and it survived cropping, scaling, filtering, additive noise and JPEG compression.

关键词： Watermarking Robustness PSNR Discrete wavelet transforms Transform coding Mobile handsets Authentication

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A wavelet coefficients based dynamic range compression technique for infrared images

A wavelet coefficients based dynamic range compression techn...

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IEEE signal processing and Communications applications (SIU)

作者： Ali Onur Karali Tayfun Aytaç TÜBİTAK BİLGEM İLTAREN Ankara Turkey

14-bit or 16-bit pixel depth high dynamic-range images are acquired from visible band cameras and from infrared imaging devices which are more widely used nowadays. Usually, linear mapping is used to display these images to operators. However, results of the researches done to map images into 0-255 range in recent years show that different techniques result in major differences at image perception and detail visibility. Successful compression of image dynamic range increases the operator awareness for surveillance systems and ensure more effective display of scene details to user. Besides, dynamic-range compression techniques effect the enhancement of the success rate of image target detection and tracking techniques. In this work, scene components are analyzed using wavelet coefficients and intensity distribution of scene components are extracted. Extracted intensity distribution is used to display scene components effectively.

关键词： Histograms Dynamic range image coding DH-HEMTs High definition video Infrared imaging Nonlinear optics

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Robust reversible watermarking scheme based on wavelet-like transform

Robust reversible watermarking scheme based on wavelet-like ...

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IEEE International conference on signal and image processing applications (ICSIPA)

作者： Rasha Thabit Mohammed Bee Ee Khoo School of Electrical and Electronic Engineering University Sains Malaysia Penang Malaysia

Watermarking reversibility is one of the basic requirements for medical imaging, military imaging, and remote sensing applications. In these fields a slight change in the original image can lead to a significant difference in the final decision making process. However, the reversibility alone is not enough for practical applications because the hidden data must be extracted even after unintentional attacks (e.g., noise addition, JPEG compression) so a robust (i.e., semi-fragile) reversible watermarking methods became required. In this paper, we present a new robust reversible watermarking method that utilizes the Slantlet transform (SLT) to transform image blocks and modifying the SLT coefficients to embed the watermark bits. If the watermarked image is not attacked, the method is completely reversible (i.e., the watermark and the original image will be recovered correctly). After JPEG compression, the hidden data can be extracted without error. Experimental results prove that the presented scheme achieves high visual quality, complete reversibility, and better robustness in comparison with the previous methods.

关键词： Robustness Transform coding image coding Watermarking Transforms

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Canny and gauss enhancement on speckle reducing anisotropic diffusion

Canny and gauss enhancement on speckle reducing anisotropic ...

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IEEE signal processing and Communications applications (SIU)

作者： Erkan Uslu Songül Albayrak Bilgisayar Mühendisliği Bölümü Yıldız Teknik Üniversitesi Istanbul Turkey

In this work speckle reduction methods defined in the literature are basically compared according to effect on classification, edge preservation and noise reduction in homogenous regions. The methods are tested on labeled SAR image, simulated SAR image and optical image. It is aimed to present mutual effect of speckle reduction methods on both edge preservation and noise reduction. One of the purposes of this work is to improve SRAD method, which is especially defined for speckle noise reduction, by combining it with Canny edge detection and Gauss filtering. It is proved by the experimental results that proposed method enhances the quality measure results.

关键词： Speckle Synthetic aperture radar signal to noise ratio Anisotropic magnetoresistance Noise reduction Discrete wavelet transforms image edge detection

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