符合人眼视觉特性的焊缝射线数字图像增强方法

摘要

For the problem of low brightness and contrast in weld radiographic images, an image enhancing strategy for human visual system is proposed. The proposed method calibrates the imaging system under the certain conditions, and finds the imaging characteristics of the original image from the calibrating results. Then the objective characteristics are obtained by the imaging poles. The gray-level mapping transformation function is gained and applied to image enhancement. The experimental results demonstrate that the proposed strategy promotes the gray level difference from 145 to 157 and the average gray from 35 to 120 without information loss. Compared with histogram equalization, the proposed strategy enables to improve the average gray of radiographic image to 120 which belongs to the high-resolution gray range of human visual system.%针对焊缝射线检测数字图像的灰度低、对比度低的问题,提出了一种符合人眼视觉特性的图像增强方法.该算法先标定数字化仪器,得到各种数字化条件下的黑度与灰度关系.其次,根据成像条件得到待处理图像的成像特性,通过该成像特性的2个极点来获得图像处理的目标特性.最后,利用由成像特性和目标特性得到的图像灰度级映射变换函数,对图像进行了空域增强处理.实验结果表明,该算法将原图的灰度级差异从145提高到157,使原图平均灰度级从35提高到120.与线性变换算法相比,该算法没有产生信息丢失；与直方图均衡算法相比,该算法将图像平均灰度级提高到120且属于人眼敏感的范围.