超快激光X射线单发照相的图像增强方法研究  

Photographic Image Enhancement for Single-Shot X-Ray Radiograph via Ultrafast Laser

作　　者：唐立平 王窈[3] 储根柏[4] 李奉笑 王亮[3] 周日峰[1,2] 何碧[3] Tang Liping;Wang Yao;Chu Genbai;Li Fengxiao;Wang Liang;Zhou Rifeng;He Bi(ICT Research Center,Key Lab of Optoelectronic Technology and Systems,Ministry of Education,Chongqing University,Chongqing 400044,China;Engineering Research Center of Industrial Computed Tomography Nondestructive Testing,Ministry of Education,Chongqing University,Chongqing 400044,China;Institute of Chemical Materials,China Academy of Engineering Physics,Mianyang 621900,Sichuan,China;Science and Technology on Plasma Physics Laboratory,Laser Fusion Research Center,China)

机构地区：[1]重庆大学光电技术及系统教育部重点实验室ICT研究中心,重庆400044 [2]重庆大学工业CT无损检测教育部工程研究中心,重庆400044 [3]中国工程物理研究院化工材料研究所,四川绵阳621900 [4]中国工程物理研究院激光聚变研究中心高温高密度等离子体物理实验室,四川绵阳621900

出　　处：《中国激光》2023年第22期124-131,共8页Chinese Journal of Lasers

基　　金：国家自然科学基金面上项目(12175026);国家自然科学基金重大科研仪器研制项目(11827809)。

摘　　要：超快激光X射线单发照相技术具有高时空分辨能力,是观测高速运动物体形态参数如内部结构、平面性等的重要手段。但由于激光X射线脉宽在皮秒或飞秒量级、X射线能谱宽、成像环境复杂等原因,导致X射线图像背景干扰噪声大、对比度低,物体形态结构准确识别和测量难度大。在传统对比度限制直方图均衡化(CLAHE)图像增强算法的基础上,提出了一种多尺度融合的改进直方图均衡化(IHEMF)算法。该算法增加自适应裁剪阈值以适应每个区域特征,并利用亮度和梯度幅值信息将增强后图像与原始图像全局融合,最后对融合后图像去噪得到最终图像。该算法既能提高感兴趣区域的对比度噪声比(CNR),又具有很好的保边界特征的能力。对高速飞片的静态、动态、终态等典型状态下X射线图像进行处理,CNR分别提升50.97%、90.43%和96.84%。实验结果表明所提算法在噪声抑制和结构保真方面优于其他算法,可为准确解读高速运动物体形态表征参数信息提供重要技术支撑。Objective Single-shot X-ray radiograph technology via ultrafast laser can be used to image the internal structure of ultra-high velocity objects with high spatial and temporal resolution,providing a new technical means to observe the internal structure,planarity and other morphological parameters of flyers.However,the wide energy spectrum of high-energy X-rays produced by laser bombardment of the target is accompanied by strong disturbances such as high-energy electrons and scattered rays,which causes great interference to X-ray imaging signal-to-noise ratio and image quality.Besides,the laser pulse width is extremely narrow(picosecond or femtosecond levels)and the data acquisition time of the radiation detector is extremely short,resulting in a low photon count,high quantum statistical noise,and low image signal-to-noise ratio.In addition,the plasma around the flyer makes it more difficult to observe the structure of the flyer,and the image quality is difficult to satisfy the application requirements of accurate observation.Finally,general image enhancement algorithms introduce unnecessary artifacts.In order to better observe and analyze the morphological structure of flyers,a special image enhancement algorithm is needed to improve the image quality.Methods Aiming at the problems of single-shot X-ray radiograph via ultrafast laser with high background noise interference,low contrast,and difficulties in morphology identification and measurement,an improved histogram equalization image enhancement algorithm based on multi-scale fusion(IHEMF)is proposed in this paper.The conventional CLAHE algorithm uses a fixed clipping threshold,which leads to excessive enhancement of the background region.The IHEMF algorithm modifies the fixed clipping threshold of the CLAHE algorithm to a gradient-dependent parameter.By calculating the horizontal gradient and vertical gradient of each block sub-region in the original image and bringing them into the constructed Gaussian function,adaptive clipping thresholds that can better fit

关 键 词：超快激光 X射线单发照相 图像增强 多尺度融合 直方图均衡化 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术]