细节保持的非均匀光照图像亮度均衡算法
|
摘要
针对目前图像增强算法应对非均匀光照环境的局限性,提出了一种同时保持低照度区域和正常照度区域细节信息的图像亮度均衡算法。算法利用像素相邻频率和位置关系生成光照滤波器,有效分离图像光照信息和反射细节信息。通过光照阈值划分光照亮暗区域进行低照度亮度补偿,从而均衡图像亮度。实验结果显示,相对于经典NPEA算法,图像平均峰值信噪比提升15.4%、平均增强度提升245.0%、平均亮度阶差下降25.4%。因此,本文算法能够在保持不同照度区域的细节信息的同时均衡亮度,获得较好的视觉效果。
In order to overcome the limitation of current image enhancement algorithms for non-uniform illumination images, a brightness equalization algorithm is proposed to preserve the detail information in low illumination region and normal illumination region at the same time. The algorithm uses the adjacent frequency and position of pixels to generate illumination filter, so it can effectively separate illumination information and reflection information with details. The illumination threshold is used to divide different illumination areas to compensate for low illumination brightness, so as to balance the image brightness. The experimental results show that compared with the classical naturalness preserved enhancement algorithm(NPEA), the average peak signal to noise ratio of the image increases by 15.4%, the average enhancement degree increases by 245.0%, and the average brightness step difference decreases by 25.4%. The results of the proposed algorithm can maintain the details of different illumination areas while balancing the brightness and obtain a better visual effect.
In order to overcome the limitation of current image enhancement algorithms for non-uniform illumination images, a brightness equalization algorithm is proposed to preserve the detail information in low illumination region and normal illumination region at the same time. The algorithm uses the adjacent frequency and position of pixels to generate illumination filter, so it can effectively separate illumination information and reflection information with details. The illumination threshold is used to divide different illumination areas to compensate for low illumination brightness, so as to balance the image brightness. The experimental results show that compared with the classical naturalness preserved enhancement algorithm(NPEA), the average peak signal to noise ratio of the image increases by 15.4%, the average enhancement degree increases by 245.0%, and the average brightness step difference decreases by 25.4%. The results of the proposed algorithm can maintain the details of different illumination areas while balancing the brightness and obtain a better visual effect.
引文
[1]Kim Y T.Contrast enhancement using brightness preserving bi-histogram equalization[J].IEEE Transactions on Consumer Electronics,1997,43(1):1-8.
[2]Wang Y,Chen Q,Zhang B.Image enhancement based on equal area dualistic sub-image histogram equalization method[J].IEEE Transactions on Consumer Electronics,1999,45(1):68-75.
[3]Chen S D,Ramli A R.Contrast enhancement using recursive mean-separate histogram equalization for scalable brightness preservation[J].IEEE Transactions on Consumer Electronics,2003,49(4):1301-1309.
[4]Tang J R,Isa N A M.Adaptive Image Enhancement based on Bi-Histogram Equalization with a clipping limit[J].Computers&Electrical Engineering,2014,40(8):86-103.
[5]Kim T,Paik J.Adaptive contrast enhancement using gain-controllable clipped histogram equalization[J].IEEETransactions on Consumer Electronics,2008,54(4):1803-1810.
[6]Kim W,You J,Jeong J.Contrast enhancement using histogram equalization based on logarithmic mapping[J].Optical Engineering,2012,51(6):067002.
[7]Lu B B,Li Y J,Zheng Y M,et al.A visual adaptive multi-scale logarithmic tone mapping algorithm[J].Journal of Chinese Computer Systems,2017,38(3):625-629.芦碧波,李玉静,郑艳梅,等.视觉自适应多尺度对数色调映射算法[J].小型微型计算机系统,2017,38(3):625-629.
[8]Lu X M,Zhu X Y,Li Z W,et al.A brightness-scaling and detail-preserving tone mapping method for high dynamic range images[J].Acta Automatica Sinica,2015,41(6):1080-1092.陆许明,朱雄泳,李智文,等.一种亮度可控与细节保持的高动态范围图像色调映射方法[J].自动化学报,2015,41(6):1080-1092.
[9]Li B,Zhu M,Fan Z K,et al.An adaptive Gamma enhancement algorithm for non-niform illumination images[J].Journal of Nanchang University(Natural Science),2016,40(3):299-302.李渤,朱梅,樊中奎,等.非均匀光照图像自适应Gamma增强算法[J].南昌大学学报(理科版),2016,40(3):299-302.
[10]Wang D W,Wang J,Xu Z J,et al.Adaptive correction algorithm for non-uniform illumination images[J].Systems Engineering and Electronics,2017,39(6):1383-1390.王殿伟,王晶,许志杰,等.一种光照不均匀图像的自适应校正算法[J].系统工程与电子技术,2017,39(6):1383-1390.
[11]Jobson D J,Rahman Z,Woodell G A.Properties and performance of a center/surround retinex[J].IEEE Transactions on Image Processing,1997,6(3):451-462.
[12]Rahman Z,Jobson D J,Woodell G A.Multi-scale retinex for color image enhancement[C]//Proceedings of 3rd IEEE International Conference on Image Processing,1996,3:1003-1006.
[13]Lin H N,Shi Z W.Multi-scale retinex improvement for nighttime image enhancement[J].Optik,2014,125(24):7143-7148.
[14]Zhao H Y,Xiao C B,Yu J,et al.A Retinex algorithm for night color image enhancement by MRF[J].Optics and Precision Engineering,2014,22(4):1048-1055.赵宏宇,肖创柏,禹晶,等.马尔科夫随机场模型下的Retinex夜间彩色图像增强[J].光学精密工程,2014,22(4):1048-1055.
[15]Wang S H,Zheng J,Hu H M,et al.Naturalness preserved enhancement algorithm for non-uniform illumination images[J].IEEE Transactions on Image Processing,2013,22(9):3538-3548.
[16]Xiao Q,Ding X H,Wang S J,et al.A halo-free and hue preserving algorithm for color image enhancement[J].Journal of Computer-Aided Design&Computer Graphics,2010,22(8):1246-1252.肖泉,丁兴号,王守觉,等.有效消除光晕现象和颜色保持的彩色图像增强算法[J].计算机辅助设计与图形学学报,2010,22(8):1246-1252.
[17]Shannon C E.A mathematical theory of communication[J].ACM SIGMOBILE Mobile Computing and Communications Review,2001,5:3-55.
[18]Agaian S S,Lentz K P,Grigoryan A M.A new measure of image enhancement[C]//IASTED International Conference on Signal Processing&Communication,2000.
[19]Kong T L,Isa N A M.Enhancer-based contrast enhancement technique for non-uniform illumination and low-contrast images[J].Multimedia Tools and Applications,2017,76(12):14305-14326.
[2]Wang Y,Chen Q,Zhang B.Image enhancement based on equal area dualistic sub-image histogram equalization method[J].IEEE Transactions on Consumer Electronics,1999,45(1):68-75.
[3]Chen S D,Ramli A R.Contrast enhancement using recursive mean-separate histogram equalization for scalable brightness preservation[J].IEEE Transactions on Consumer Electronics,2003,49(4):1301-1309.
[4]Tang J R,Isa N A M.Adaptive Image Enhancement based on Bi-Histogram Equalization with a clipping limit[J].Computers&Electrical Engineering,2014,40(8):86-103.
[5]Kim T,Paik J.Adaptive contrast enhancement using gain-controllable clipped histogram equalization[J].IEEETransactions on Consumer Electronics,2008,54(4):1803-1810.
[6]Kim W,You J,Jeong J.Contrast enhancement using histogram equalization based on logarithmic mapping[J].Optical Engineering,2012,51(6):067002.
[7]Lu B B,Li Y J,Zheng Y M,et al.A visual adaptive multi-scale logarithmic tone mapping algorithm[J].Journal of Chinese Computer Systems,2017,38(3):625-629.芦碧波,李玉静,郑艳梅,等.视觉自适应多尺度对数色调映射算法[J].小型微型计算机系统,2017,38(3):625-629.
[8]Lu X M,Zhu X Y,Li Z W,et al.A brightness-scaling and detail-preserving tone mapping method for high dynamic range images[J].Acta Automatica Sinica,2015,41(6):1080-1092.陆许明,朱雄泳,李智文,等.一种亮度可控与细节保持的高动态范围图像色调映射方法[J].自动化学报,2015,41(6):1080-1092.
[9]Li B,Zhu M,Fan Z K,et al.An adaptive Gamma enhancement algorithm for non-niform illumination images[J].Journal of Nanchang University(Natural Science),2016,40(3):299-302.李渤,朱梅,樊中奎,等.非均匀光照图像自适应Gamma增强算法[J].南昌大学学报(理科版),2016,40(3):299-302.
[10]Wang D W,Wang J,Xu Z J,et al.Adaptive correction algorithm for non-uniform illumination images[J].Systems Engineering and Electronics,2017,39(6):1383-1390.王殿伟,王晶,许志杰,等.一种光照不均匀图像的自适应校正算法[J].系统工程与电子技术,2017,39(6):1383-1390.
[11]Jobson D J,Rahman Z,Woodell G A.Properties and performance of a center/surround retinex[J].IEEE Transactions on Image Processing,1997,6(3):451-462.
[12]Rahman Z,Jobson D J,Woodell G A.Multi-scale retinex for color image enhancement[C]//Proceedings of 3rd IEEE International Conference on Image Processing,1996,3:1003-1006.
[13]Lin H N,Shi Z W.Multi-scale retinex improvement for nighttime image enhancement[J].Optik,2014,125(24):7143-7148.
[14]Zhao H Y,Xiao C B,Yu J,et al.A Retinex algorithm for night color image enhancement by MRF[J].Optics and Precision Engineering,2014,22(4):1048-1055.赵宏宇,肖创柏,禹晶,等.马尔科夫随机场模型下的Retinex夜间彩色图像增强[J].光学精密工程,2014,22(4):1048-1055.
[15]Wang S H,Zheng J,Hu H M,et al.Naturalness preserved enhancement algorithm for non-uniform illumination images[J].IEEE Transactions on Image Processing,2013,22(9):3538-3548.
[16]Xiao Q,Ding X H,Wang S J,et al.A halo-free and hue preserving algorithm for color image enhancement[J].Journal of Computer-Aided Design&Computer Graphics,2010,22(8):1246-1252.肖泉,丁兴号,王守觉,等.有效消除光晕现象和颜色保持的彩色图像增强算法[J].计算机辅助设计与图形学学报,2010,22(8):1246-1252.
[17]Shannon C E.A mathematical theory of communication[J].ACM SIGMOBILE Mobile Computing and Communications Review,2001,5:3-55.
[18]Agaian S S,Lentz K P,Grigoryan A M.A new measure of image enhancement[C]//IASTED International Conference on Signal Processing&Communication,2000.
[19]Kong T L,Isa N A M.Enhancer-based contrast enhancement technique for non-uniform illumination and low-contrast images[J].Multimedia Tools and Applications,2017,76(12):14305-14326.