基于剪切波域改进Gamma校正的医学图像增强算法

通过傅里叶光学理论和透镜成像理论对轴棱锥线 聚焦与凸透镜点聚焦两种成像系统进行分析, 并探讨了它们对成像系统焦深的影响。利用ZEMAX光学设计软件,仿真模拟出系统在不同轴 向距离的截面 光强分布图。以蓝光LED为光源,对这两种成像系统进行实验验证,拍摄不同轴向距离处的 截面光强分布 图。结果表明,轴棱锥所具有的线聚焦特性,能将光线连续地会聚到沿轴线不同位置上,图 像的清晰度高, 且在最大无衍射距离内无需调焦,具有更大的焦深；理论分析、仿真模拟与实验结果相吻合 。

Medical image enhancement method based on improved Gamma correction in Shearlet domain

Noises and artifacts are introduced to medical images in the process of acquisit ion and transmission,which causes image degradation and further seriously affect s the clinical diagnoses.Therefore,in order to solve this problem,a medical imag es enhancement method based on shearlet transformation and improved gamma correctio n is proposed in this paper.First,the original image is decomposed into the shearlet domain with low-frequency component and high-frequency component.Then,the improved gamma correction is adopted for the low-frequency component to improve the global contrast of the image,and an adap tive threshold method is used for the removal of high-frequency image noise.Finally,the improved fu zzy contrast is used to enhance the details of the reconstruct image which is obtained by the sh earlet inverse transformation.The experimental results show that the proposed method is super ior to other comparative methods in peak signal to noise ratio (PSNR) ,structural similarity (SSIM) and mean absolute error (MAE),especially the PSNR is increased observably.These objective criterions indicate that the proposed method not only can remove image noise efficiently, but also significantly improve the contrast of image.In the subjective aspect, the proposed method can get better visual effect than other methods.