改进非线性亮度提升模型的逆光图像恢复

摘要

针对因为拍照时光线不足或拍摄角度不佳而拍出逆光图像影响肉眼观察或计算机识别的问题,提出一种改进的非线性亮度提升模型的逆光图像恢复手段.已有的非线性亮度提升方法虽然能够提高逆光区域的亮度,但往往由于过度提升导致高亮度区域失真.在已有的图像亮度处理算法基础上,提出基于非线性亮度提升模型的自适应逆光图像恢复方法,采用对数函数的转换关系对图像亮度进行分段处理,其分段阈值由Otsu阈值分割决定,其转换函数中逆光区域的调节系数由逆光区像素面积比计算得到.仿真结果显示,新方法提升了图像质量且确保了整幅图片自然不失真,与利用对数函数转换关系,并在HSI空间模型下对图像亮度进行调节的方法相比,提升了处理性能.%Photo observation and identification is often influenced by insufficient light and unsuitable shooting angle when taking photos.In order to solve this problem,an image restoration method based on nonlinear brightness-lifting model was proposed.Although the existing nonlinear brightness enhancement method can improve the brightness of the backlight area,distortion still occurs in the highlighted area due to excessive promotion.On the basis of the existing image processing algorithm,a new adaptive backlight images restoration method based on nonlinear brightness improvement model was proposed.Image segmentation processing and logarithmic function were used to enhance image brightness,in which the threshold was determined by Otsu threshold processing,and the adjustment coefficient in the transition function was calculated by the ratio between pixels of backlight area and total pixels.Simulation results show that,compared with the method of using the logarithmic function conversion relation and adjusting the image brightness in the HSI space model,the proposed method not only improves the image quality and preserves the nature of image without distortion,but also has a good improvement in performance.