Hyperspectral Images Classification Using Energy Profiles of Spatial and Spectral Features

This paper proposes a spatial feature extraction method based on energy of the features for classification of the hyperspectral data. A proposed orthogonal filter set extracts spatial features with maximum energy from the principal components and then, a profile is constructed based on these features. The important characteristic of the proposed approach is that the filter sets coefficients are extracted from statistical properties of data, thus they are more consistent with the type and texture of the remotely sensed images compared with those of other filters such as Gabor. To assess the performance of the proposed feature extraction method, the extracted features are fed into a support vector machine (SVM) classifier. Experiments on the widely used hyperspectral images namely, Indian Pines, and Salinas data sets reveal that the proposed approach improves the classification results in comparison with some recent spectral spatial classification methods.

Improved Adaptive Brovey as a New Method for Image Fusion

An ideal fusion method preserves the Spectral information in fused image and adds spatial information to it with no spectral distortion. Among the existing fusion algorithms, the contourlet-based fusion method is the most frequently discussed one in recent publications, because the contourlet has the ability to capture and link the point of discontinuities to form a linear structure. The Brovey is a popular pan-sharpening method owing to its efficiency and high spatial resolution. This method can be explained by mathematical model of optical remote sensing sensors. This study presents a new fusion approach that integrates the advantages of both the Brovey and the cotourlet techniques to reduce the color distortion of fusion results. Visual and statistical analyzes show that the proposed algorithm clearly improves the merging quality in terms of: correlation coefficient, ERGAS, UIQI, and Q4; compared to fusion methods including IHS, PCA, Adaptive IHS, and Improved Adaptive PCA.

Panchromatic Sharpening of Remote Sensing Images Using a Multi-scale Approach

An ideal fusion method preserves the Spectral information in fused image and adds spatial information to it with no spectral distortion. Recently wavelet kalman filter method is proposed which uses ARSIS concept to fuses MS and PAN images. This method is applied in a multiscale version, i.e. the variable index is scale instead of time. With the aim of fusion we present a more detailed study on this model and discuss about rationality of its assumptions such as first order markov model and Gaussian distribution of the posterior density. Finally, we propose a method using wavelet Kalman Particle filter to improve the spectral and spatial quality of the fused image. We show that our model is more consistent with natural MS and PAN images. Visual and statistical analyzes show that the proposed algorithm clearly improves the fusion quality in terms of: correlation coefficient, ERGAS, UIQI, and Q4; compared to other methods including IHS, HMP, PCA, A`trous, udWI, udWPC, Adaptive IHS, Improved Adaptive PCA and wavelet kalman filter.

A new ultrasound despeckling method through adaptive threshold

An efficient despeckling method using a quantum-inspired adaptive threshold function is presented for reducing noise of ultrasound images. In the first step, the ultrasound image is decorrelated by an spectrum equalization procedure due to the fact that speckle noise is neither Gaussian nor white. In fact, a linear filter is exploited to flatten the power spectral density (PSD) of the ultrasound image. Then, the proposed method shrinks complex wavelet coefficients based on the quantum-inspired adaptive threshold function. The proposed approach has been used to denoise both real and simulated data sets and compare with other widely adopted techniques. Experimental results demonstrate that the proposed method has a competitive performance to remove speckle noise and can preserve details and textures of medical ultrasound images.

Image denoising through bivariate shrinkage function in framelet domain

Denoising of coefficients in a sparse domain (e.g. wavelet) has been researched extensively because of its simplicity and effectiveness. Literature mainly has focused on designing the best global threshold. However, this paper proposes a new denoising method using bivariate shrinkage function in framelet domain. In the proposed method, maximum aposteriori probability is used for estimate of the denoised coefficient and non-Gaussian bivariate function is applied to model the statistics of framelet coefficients. For every framelet coefficient, there is a corresponding threshold depending on the local statistics of framelet coefficients. Experimental results show that using bivariate shrinkage function in framelet domain yields significantly superior image quality and higher PSNR than some well-known denoising methods.

Robust non-local means filter for ultrasound image denoising

This paper introduces a new approach to non-local means image denoising. Instead of using all pixels located in the search window for estimating the value of a pixel, we identify the highly corrupted pixels and assign less weight to these pixels. This method is called robust non-local means. Numerical and subjective evaluations using ultrasound images show good performances of the proposed denoising method in recovering the shape of edges and important detailed components, in comparison to traditional ultrasound image denoising methods

A New Multifocus Image Fusion Method Using Contourlet Transform

A new multifocus image fusion approach is presented in this paper. First the contourlet transform is used to decompose the source images into different components. Then, some salient features are extracted from components. In order to extract salient features, spatial frequency is used. Subsequently, the best coefficients from the components are selected by the maximum selection rule. Finally, the inverse contourlet transform is applied to the selected coefficients. Experiments show the superiority of the proposed method.

Improving high-pass fusion method using wavelets

In an appropriate image fusion method, spatial information of the panchromatic image is injected into the multispectral images such that the spectral information is not distorted. The high-pass modulation method is a successful method in image fusion. However, the main drawback of this method is that this technique uses the boxcar filter to extract the high frequency information of the panchromatic image. Using the boxcar filter introduces the ringing effect into the fused image. To cope with this problem, we use the wavelet transform instead of boxcar filters. Then, the results of the proposed method and those of other methods such as, Brovey, IHS, and PCA ones are compared. Experiments show the superiority of the proposed method in terms of correlation coefficient and mutual information.

Using Complex Wavelet Transform and Bilateral Filtering for Image Denoising

The bilateral filter is a useful nonlinear filter which without smoothing edges, it does spatial averaging. In the literature, the effectiveness of this method for image denoising is shown. In this paper, an extension of this method is proposed which is based on complex wavelet transform. In fact, the bilateral filtering is applied to the low-frequency (approximation) subbands of the decomposed image using complex wavelet transform, while the thresholding approach is applied to the high frequency subbands. Using the bilateral filter in the complex wavelet domain forms a new image denoising framework. Experimental results for real data are provided, by which one can see the effectiveness of the proposed method in eliminating noise.

A New Method for Removing the Moire' Pattern from Images

During the last decades, denoising methods have attracted much attention of researchers. The conventional method for removing the Moire' pattern from images is using notch filters in the Frequency-domain. In this paper a new method is proposed that can achieve a better performance in comparison with the traditional method. Median filter is used in some part of spectrum of noisy images to reduce the noise. At the second part of this paper, to demonstrate the robustness of the proposed method, it is implemented for some noisy images that have moire' pattern. Experiments on noisy images with different characteristics show that the proposed method increases the PSNR values compared with previous methods.