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国家自然科学基金(61070138)

作品数:5 被引量:21H指数:3
相关作者:刘哲陈路杨静杨健张丽更多>>
相关机构:西北工业大学更多>>
发文基金:国家自然科学基金更多>>
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JPEG stream soft-decoding technique based on autoregressive modeling被引量:3
2012年
This paper introduces a new model-based soft decoding techniqt, e to restore the widely used joint photographic expert group (JPEG) streams. The image is modeled as a two dimensional (2D) piecewise stationary autoregressive process, and the decoding task is formulated as a constrained optimization problem. All the constraints are given by the quantization intervals which available at the decoder freely. The autoregressive model serves as an important regularization term of the objective function of the optimization, and the model parameters are solved on the decoded image locally using a weighted total least square method. In addition, a novel bilateral dualside weighting scheme is proposed to minimize the influence of the blocking artifact on the accuracy of parameter estimation. Extensive experimental results suggest that the proposed algorithm systematically improves the quality of JPEG images and also outperforms existing JPEG postprocessing algorithms in a wide bit-rate range both in terms of peak signal-to-noise ratio (PSNR) and subjective quality
NIU YiSHI Guang-mingWANG Xiao-tianWANG Li-zhiGAO Da-hua
Random projection method for ultra wideband signal acquisition
2011年
High-speed high-resolution analog-to-digital (A/D) conversion demanded by ultra wideband (UWB) signal processing is a very challenging problem. This paper proposes a parallel random projection method for UWB signal acquisition. The proposed method can achieve high sampling rate, high resolution and technical feasibility of hardware implementation. In the proposed method, an analog UWB signal is projected over a set of random sign functions. Then the low-rate high-resolution analog-to-digital convertors (ADCs) are used to sample the projection coefficients. The signal can be reconstructed by simple linear calculation with the sampling matrix, without complying with optimization algorithm and prior knowledge. In other aspects, unlike other approaches that need to utilize an accurate time-shift at extremely high frequency, or design a hybrid filter bank, or generate specific basis functions or work for signals with prior knowledge, the proposed method is a universal sampling approach and easy to apply. The simulation results of signal to noise ratio (SNR) and spurious-free dynamic range (SFDR) validate the efficiency of the proposed method for UWB signal acquisition.
LIN Jie SHI Guang-ming CHEN Xu-yang ZHANG Li
基于非局部稀疏编码的超分辨率图像复原被引量:7
2015年
基于压缩感知的超分辨率图像复原方法通常采用局部稀疏编码策略,对每一图像块独立编码,易产生人工的分块效应。针对上述问题,该文提出一种基于非局部稀疏编码的超分辨率图像复原方法。该算法在字典训练和图像编码过程中分别运用图像的非局部自相似先验知识,即利用低分辨率图像的插值图像训练字典,并通过计算相似块局部编码的加权平均,得到每一图像块的非局部稀疏编码。仿真实验表明,所提算法能够获得更优的复原效果,并且对于含噪图像具有较强的鲁棒性。
刘哲杨静陈路
关键词:超分辨率图像复原压缩感知
基于椭圆傅里叶描述子的遥感图像配准算法被引量:8
2015年
传统的基于点特征的图像配准算法在遥感图像配准时提取的特征点数量大、分布密,易产生误匹配,导致特征匹配的效率和精度低。为此,本文利用椭圆傅里叶描述子(EFD)能较好保留形状信息的特点,提出了一种基于EFD的图像配准算法,根据匹配的边界对预估变换参数,给出特征搜索范围,从而有效地提高特征搜索的效率。实验结果表明,所提出算法能有效抑制误匹配的产生,提升特征匹配的效率,尤其是对于纹理丰富的大尺寸图像,提升效果更加明显,验证了本文算法对遥感图像配准的适用性。
刘哲杨健张丽
关键词:图像配准
结合稀疏表示与匹配梯度分布的图像复原被引量:3
2015年
针对基于稀疏表示的传统图像复原方法无法准确恢复图像小尺度细节的不足,提出了一种结合稀疏表示与匹配梯度分布的图像复原方法。首先在稀疏表示图像复原模型的基础上,利用参数化的超拉普拉斯分布估计原始图像的梯度分布;然后,通过对图像的梯度分布进行全局约束,利用梯度直方图匹配操作匹配图像梯度分布,使复原图像的梯度分布尽可能接近原始图像。仿真实验结果表明,本文算法能够取得较优的复原效果,并且能以较高精度复原图像的细节信息。
刘哲杨静陈路
关键词:图像复原
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