热态重轨图像光照不均校正方法

为抑制重轨弧面强反射场引起的局部亮度过大,同时保留足够多的原始图像信息.研究了线像素灰度处理方法,计算列像素均值,去均值化处理实现纵向光照不均校正;选取上边缘的n个离散点,三次B样条边缘拟合,y方向像素对齐实现边缘矫直,然后对每一行的像素进行叠加,将灰度均值作为基准,根据每一行像素灰度和基准的比值进行线性拉伸,实现横向光照不均校正.引入信息熵、均方误差、峰值信噪比、通用图像质量指数量化比较不同方法的处理效果.对比实验表明,文中方法得到的图像总体灰度值分布最均匀,图像质量评价参数最高.该方法校正了图像亮度的不均匀性,同时能保留足够多的原始图像信息.

Correction Method of Poor Illumination for Hot Heavy Rail

To restrain the phenomenon of local excessive brightness caused by the strong reflection from arc of the heavy rail, and retain enough of the original image information, lines-pixel of gray pro- cessing was investigated amply, the average of column-pixel was calculated and subtracted for vertical poor illumination correction, n discrete points were used for cubic B-Spline edge fitting, y directional pixel was alignment to realize the edge straighten out, and then, every raw-pixel was added, with the gray average as benchmark, according to the ratio of every raw-pixel and benchmark to linear stretch, to realize the transverse poor illumination correction, lines-pixel of gray processing was contrasted with the other ways of image processing effects with gray entropy, mean square error（MSE）, peak signal-to-noise ratio（PSNR）, universal image quality index（UIQI）. The experiment indicates that the distribution of image gray value most uniform and image quality evaluation parameters maximum with the lines-pixel of gray processing algorithm. This method amends the image luminance heterogeneity, preserves sufficient original image information.