Hyperspectral remote sensing has been widely utilized in high-resolution climate observation, environment monitoring, resource mapping, etc. However, it brings undesirable difficulties for transmission and storage due to the huge amount of the data. Lossless compression has been demonstrated to be an efficient strategy to solve these problems. In this paper, a novel Band Regrouping based Lossless Compression (BRLlC) algorithm is proposed for lossless compression of hyperspectral images. The affinity propagation clustering algorithm, which can achieve adaptive clustering with high efficiency, is firstly applied to classify all of the hyperspectral bands into several groups based on the inter-band correlation matrix of hyperspectral images. Consequently, hyperspectral bands with high correlation are clustered into one group so that the prediction efficiency in each group can be greatly enhanced. In addition, a linear prediction algorithm based on context prediction is applied to the hyperspectral images in each group followed by arithmetic coding. Experimental results demonstrate that the proposed algorithm outperforms some classic lossless compression algorithms in terms of bit per pixel per band and in terms of processing performance.
A lossy hyperspectral images compression algorithm based on discrete wavelet transform (DWT) and segmented
independent component analysis is presented in this paper. Firstly, bands are divided into different groups based on the
correlation coefficient. Secondly, maximum noise fraction (MNF) method and maximum likelihood estimation are used
to estimate dimensionality of data in each group. Based on the result of dimension estimation, ICA and DWT are
deployed in spectral and spatial directions respectively. Finally, SPIHT and arithmetic coding are applied to the
transformation coefficients respectively, achieving quantization and entropy coding. Experimental results on 220 band
AVIRIS hyperspectral data show that the proposed method achieves higher compression ratio and better analysis
capability as compared with PCA and SPIHT algorithms.
This paper proposes a new regularization algorithm combining the wavelet-based and contourlet-based regularization
items based on the Compressive Sensing (CS) theorem. The new algorithm aims at gaining maximum benefit by
combining the multiscale and multiresolution properties common to both wavelet and contourlet schemes, while
simultaneously incorporating their individual properties of point singularity and line singularity respectively. CS is
applied to remote sensing image deblurring. It has great practical significance due to saving the hardware cost and aiding
fast transmission. Experimental results show the method achieves improvement in peak-signal-noise-ratio and
correlation function as compared to traditional regularization algorithms.
Hyperspectral image has weak spatial correlation and strong spectral correlation. As to exploit spectrum redundancy
sufficiently, it must be pre-processed. In this paper, a new algorithm for lossless compression of hyperspectral images
based on adaptive band regrouping is proposed. Firstly, the affinity propagation clustering algorithm (AP) is chosen for
band regrouping according to interband correlation. Then a linear prediction algorithm based on context prediction is
applied to the hyperspectral images in different groups. Finally, the experimental results show that the proposed
algorithm achieves performance gains of 1.12bpp over the conventional algorithm.
In the most application situation, signal or image always is corrupted by additive noise. As a result there are mass
methods to remove the additive noise while few approaches can work well for the multiplicative noise. The paper
presents an improved MAP-based filter for multiplicative noise by adaptive window denoising technique. A Gamma
noise models is discussed and a preprocessing technique to differential the matured and un-matured pixel is applied to
get accurate estimate for Equivalent Number of Looks. Also the adaptive local window growth and 3 different denoise
strategies are applied to smooth noise while keep its subtle information according to its local statistics feature. The
simulation results show that the performance is better than existing filter. Several image experiments demonstrate its
theoretical performance.
Due to the spatial resolution limitation, mixed pixels containing energy reflected from more than one type of ground object will present, which often results in inefficiency in the quantitative analysis of the remote sensing images. To address this problem, a fully constrained linear unmixing algorithm based on Hopfield Neural Network (HNN) is proposed in this paper. The Nonnegative constraint, which has no close-form analytical solution, is secured by the activation function of neurons instead of traditional numerical method. The Sum-to-one constraint is embedded in the HNN by adopting the least square Linear Mixture Model (LMM) as the energy function. The Noise Energy Percentage (NEP) stop criterion is also proposed for the HNN to improve its robustness to various noise levels. The proposed algorithm has been compared with the widely used Fully Constrained Least Square (FCLS) algorithm and the Gradient Descent Maximum Entropy (GDME) algorithm on two sets of benchmark simulated data. The experimental results demonstrate that this novel approaches can decompose mixed pixels more accurately regardless of how much the endmember overlaps. The HNN based unmixing algorithm also shows satisfied performance in the real data experiments.
Advances in sensor technology for Earth observation make it possible to collect multispectral data in much higher dimensionality. Such high dimensional data will it possible to classify more classes. However, it will also have several impacts on processing technology. First, because of its huge data, more processing power will be needed to process such high dimensional data. Second, because of its high dimensionality and the limited training samples, it is very difficult for Bayes method to estimate the parameters accurately. So the classification accuracy cannot be high enough. Neural Network is an intelligent signal processing method. MLFNN (Multi-Layer Feedforward Neural Network) directly learn from training samples and the probability model needs not to be estimated, the classification may be conducted through neural network fusion of multispectral images. The latent information about different classes can be extracted from training samples by MLFNN. However, because of the huge data and high dimensionality, MLFNN will face some serious difficulties: (1) There are many local minimal points in the error surface of MLFNN; (2) Over-fitting phenomena. These two difficulties depress the classification accuracy and generalization performance of MLFNN. In order to overcome these difficulties, the author proposed DPFNN (Double Parallel Feedforward Neural Networks) used to classify the high dimensional multispectral images. The model and learning algorithm of DPFNN with strong generalization performance are proposed, with emphases on the regularization of output weights and improvement of the generalization performance of DPFNN. As DPFNN is composed of MLFNN and SLFNN (Single-Layer Feedforward Neural Network), it has the advantages of MLFNN and SLFNN: (1) Good nonlinear mapping capability; (2) High learning speed for linear-like problem. Experimental results with generated data, 64-band practical multispectral images and 220-band multispectral images show that the new algorithm can overcome the over-fitting phenomena effectively and improve the generalization performance of DPFNN greatly. The classification accuracy of DPFNN with the new learning algorithm is much better than the traditional one.
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