为了提升稀疏角度CT图像重建的质量效率,提出外点惩罚函数增广Lagrangian算法——EPFALM(Exterior Penalty Function Augmented Lagrangian Method)算法。提出新的稀疏角度目标函数并求解;通过仿真实验,将该算法与FBP(Filtered Back Pro...为了提升稀疏角度CT图像重建的质量效率,提出外点惩罚函数增广Lagrangian算法——EPFALM(Exterior Penalty Function Augmented Lagrangian Method)算法。提出新的稀疏角度目标函数并求解;通过仿真实验,将该算法与FBP(Filtered Back Projection)算法、ART(Algebraic Reconstruction Technique)算法、分离Bregman算法、UIAL算法做比较,验证了EPFALM算法用于稀疏CT图像重建时的质量和效率优势。仿真实验结果表明,该算法重建的图像很好地抑制了伪影,图像细节也较为清晰。展开更多
为了提高低分辨率模糊图像的质量,提出了一种基于自适应双l_p-l_2范数的超分辨率盲重建方法。该方法分为模糊核估计子过程和超分辨率非盲重建子过程。在模糊核估计子过程中,使用双l_p-l_2范数先验同时约束锐化图像和模糊核的估计,并使...为了提高低分辨率模糊图像的质量,提出了一种基于自适应双l_p-l_2范数的超分辨率盲重建方法。该方法分为模糊核估计子过程和超分辨率非盲重建子过程。在模糊核估计子过程中,使用双l_p-l_2范数先验同时约束锐化图像和模糊核的估计,并使用图像梯度的阈值分割,实现锐化图像l_p-l_2范数约束的自适应组合;在超分辨率非盲重建子过程中,结合估计到的模糊核,使用基于非局部中心化稀疏表示的超分辨率方法重建出最终的高分辨率图像。仿真实验中,与基于双l_0-l_2范数的方法相比,该算法重建结果的平均峰值信噪比(PSNR)提高了0.16 d B,平均结构相似度(SSIM)提高了0.004 5,平均差方和比降低了0.13。实验结果表明,所提方法能估计出较准确的模糊核,最终的重建图像中,振铃得到有效抑制,图像质量较好。展开更多
The augmented Lagrangian penalty formulation and four different coordination strategies are used to examine the nu- merical behavior of Analytical Target Cascading (ATC) for multilevel optimization of hierarchical sys...The augmented Lagrangian penalty formulation and four different coordination strategies are used to examine the nu- merical behavior of Analytical Target Cascading (ATC) for multilevel optimization of hierarchical systems. The coordination strategies considered include augmented Lagrangian using the method of multipliers and alternating direction method of multipliers, diagonal quadratic approximation, and truncated diagonal quadratic approximation. Properties examined include computational cost and solution accuracy based on the selected values for the different parameters that appear in each formulation. The different strategies are implemented using two- and three-level decomposed example problems. While the results show the interaction between the selected ATC formulation and the values of associated parameters, they clearly highlight the impact they could have on both the solution accuracy and computational cost.展开更多
文摘为了提升稀疏角度CT图像重建的质量效率,提出外点惩罚函数增广Lagrangian算法——EPFALM(Exterior Penalty Function Augmented Lagrangian Method)算法。提出新的稀疏角度目标函数并求解;通过仿真实验,将该算法与FBP(Filtered Back Projection)算法、ART(Algebraic Reconstruction Technique)算法、分离Bregman算法、UIAL算法做比较,验证了EPFALM算法用于稀疏CT图像重建时的质量和效率优势。仿真实验结果表明,该算法重建的图像很好地抑制了伪影,图像细节也较为清晰。
文摘为了提高低分辨率模糊图像的质量,提出了一种基于自适应双l_p-l_2范数的超分辨率盲重建方法。该方法分为模糊核估计子过程和超分辨率非盲重建子过程。在模糊核估计子过程中,使用双l_p-l_2范数先验同时约束锐化图像和模糊核的估计,并使用图像梯度的阈值分割,实现锐化图像l_p-l_2范数约束的自适应组合;在超分辨率非盲重建子过程中,结合估计到的模糊核,使用基于非局部中心化稀疏表示的超分辨率方法重建出最终的高分辨率图像。仿真实验中,与基于双l_0-l_2范数的方法相比,该算法重建结果的平均峰值信噪比(PSNR)提高了0.16 d B,平均结构相似度(SSIM)提高了0.004 5,平均差方和比降低了0.13。实验结果表明,所提方法能估计出较准确的模糊核,最终的重建图像中,振铃得到有效抑制,图像质量较好。
文摘The augmented Lagrangian penalty formulation and four different coordination strategies are used to examine the nu- merical behavior of Analytical Target Cascading (ATC) for multilevel optimization of hierarchical systems. The coordination strategies considered include augmented Lagrangian using the method of multipliers and alternating direction method of multipliers, diagonal quadratic approximation, and truncated diagonal quadratic approximation. Properties examined include computational cost and solution accuracy based on the selected values for the different parameters that appear in each formulation. The different strategies are implemented using two- and three-level decomposed example problems. While the results show the interaction between the selected ATC formulation and the values of associated parameters, they clearly highlight the impact they could have on both the solution accuracy and computational cost.
