提出一种基于变分Retinex的遥感影像灰度不均匀性校正方法。该方法在Retinex框架上,利用变分最优化技术和投影归一化最速下降法求解成像瞬间的照度分布,并以此为基础对遥感影像的灰度不均匀性进行校正。为提高运算效率,引入多尺度数值求解的策略。利用模拟影像和真实影像进行试验,并与传统方法进行对比分析,结果表明,本文方法能够在消除影像灰度不均匀现象的同时,有效保持影像本身的色彩和细节信息,同时还具有较高的运算效率。
A new uneven illumination correction method for optical remote sensing image is presented.The method is based on the Retinex theory and the variational function is used to estimate the uneven illumination distribution in the imaging instant.Retinex theory addresses the problem of separating the illumination from the reflectance in a given image,which in general is an ill-posed problem.The color sensation for any area in an image does not depend on illumination but on reflectance which should be retained.In the variational Retinex framework,the projected normal steepest descent optimization method is applied to solve the function and the multi-resolution numerical solution is introduced to improve the algorithm efficiency.The proposed algorithm was tested on a synthetic image and two real aerial images.Experimental results validated that the proposed algorithm outperforms the traditional methods in terms of the calculation efficiency,the quantitative measurements and visual evaluation.