基于信息冗余的小波红外图像去噪算法

红外图像具有图像灰度集中、对比度低等特点,因而红外图像增强是红外图像应用必不缺少的部分,随之而来的是图像噪声的放大,为了进一步提高红外图像质量,需对增强后图像去噪。现有众多去噪方法中,极少同时兼顾算法效果及可实现性。提出了一种基于信息冗余的小波去噪算法,此算法在离散小波变化(DWT)过程中分别以不同的下采样方式获取多组含有相似冗余信息的小波系数,再利用噪声估计对小波系数进行非线性变换,抑制高频噪声并保留细节,然后利用变换后小波系数重构(IDWT)多副图像,利用含相似冗余信息的多副图像加权进一步去除高频噪声,获取最终去噪图像。此算法已在单片FPGA中进行实现,利用ALTERA CYCLONIII芯片实现后的处理帧频达到50 fps,满足实时性要求。     

基于Sigmoid-iCAM色貌模型的真实影像再现算法

为了模拟人类视觉系统成像机制,真实再现人眼对外界场景的视觉感知,为机器视觉提供符合生物视觉特性的理想图像,从色度学的角度研究了彩色图像的真实影像再现技术。针对色貌模型存在图像模糊、对比度低的缺点,在iCAM色貌模型的基础上,引入了人工神经网络的非线性Sigmoid函数,提出了基于Sigmoid-iCAM色貌模型的真实影像再现算法,并给出了该模型处理不同类型图像的控制参数统计规律。与基于CIECAM02、iCAM色貌模型的真实影像再现算法相比,该算法在对色调失真图像实现颜色复原的同时,有效地提高了图像的对比度和局部细节,很好地实现了视觉系统的颜色恒定性。     

Unsupervised regions of interest extraction for color image compression

A novel unsupervised approach for regions of interest (ROI) extraction that combines the modified visual attention model and clustering analysis method is proposed. Then the non-uniform color image compression algorithm is followed to compress ROI and other regions with different compression ratios through the JPEG image compression algorithm. The reconstruction algorithm of the compressed image is similar to that of the JPEG algorithm. Experimental results show that the proposed method has better performance in terms of compression ratio and fidelity when comparing with other traditional approaches.     

Double Wronskian Soliton Solution for Mixed AKNS System

The Lax pair of the mixed Ablowitz-Kap-Newell-Segur （AKNS） system is obtained from compatibility condition. Hirota＇s bilinear form is derived by some dependent variable transformation. Moreover, by means of the Wronskian technique, the double Wronskian form of soliton solutions are found. Specially, the two-soliton solution is presented.     

高超声速再入体表面热流计算

运用非结构网格计算外部无粘流场,并结合边界层内粘性主导区域的工程算法,计算高超声速飞行器的气动加热。通过求解三维Euler方程确定复杂外形飞行器的边界层外缘参数,在理论与经验公式的基础上,利用局部相似性解的方法计算了钝锥和钝双锥外形有攻角再入的表面热流,并与国内外文献的NS方程数值计算结果和风洞试验结果进行了对比,三者的结果吻合较好。