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For sparse signals (direct or indirect), sparse imaging methods can break through limitations of the conventional SAR methods. In this paper, we introduce the basic theory of sparse representation and reconstruction, and then implements several imaging algorithms including FFT and sparse methods. Through comparison, we conclude a good sparse reconstruction algorithm in SAR imaging. Besides, a new...
A progressive SAR imaging technique is proposed as a novel SAR raw data processing scheme in this paper. Different from the classic SAR imaging algorithms which focus the SAR raw data as a whole regardless of the backscattering signal, the novel scheme discriminate the backscattering signal and choose the proper ones to be focused progressively according to some application context while the others...
A radar imaging algorithm named reciprocal spectrum algorithm (RSA) is proposed in this paper to get higher resolution in azimuth direction with frequency sampling waveform. Theoretical analysis and simulation results show that the algorithm can give better performance than the tradition range Doppler algorithm (RDA) at the cost of peak value reduction at the object points in radar image.
Speckle reduction is a prerequisite for many synthetic aperture radar (SAR) image processing tasks. In recent years, the hidden Markov tree (HMT) in wavelet domain is widely used for speckle reduction. The HMT model captures the persistence property of wavelet coefficients, but lacks the clustering property of them within a scale, whereas the Gaussian Markov random field (GMRF) model can characterize...
Synthetic aperture radar (SAR) is a kind of coherent imaging system that produces a random pattern, named speckle, which degrades the quality of SAR images and affects their further application seriously. Therefore how to restore SAR image from speckled one has become a necessary step in post-processing of image. In this paper, a new despeckling algorithm is presented based on wavelet transform using...
Synthetic Aperture Radar (SAR) image despeckling is an important problem in the SAR applications. The demand for the speckle reduction of SAR images is to smooth the speckle noise while preserving the structure information of the original images. Because contourlet is a new and more effective signal representation tool than wavelet in many image applications, we propose an improved despeckling method...
The granular appearance of speckle noise in synthetic aperture radar (SAR) imagery makes it very difficult to visually and automatically interpret SAR data. Therefore, speckle reduction is a prerequisite for many SAR image processing tasks. In this paper, we propose a contourlet-based despeckling method for the SAR image using the hidden Markov tree (HMT) and Gaussian Markov models. The contourlet...
Synthetic aperture radar (SAR) images are corrupted by speckle noise, which degrades the quality and interpretation. One of the most traditional speckle filters, the Gamma maximum-a-posteriori (GMAP) speckle filter, is based on the first order texture models in SAR images, i.e. the local mean and local variance, without the consideration of the correlation present in the SAR images. To enhance the...
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