面向视频侦查的局部过曝抑制降采样白斑算法  

An Algorithm on Downsampling White Patches Inhibiting Local Overexposed Pixels for Video Investigation

作　　者：李众邦 解梦达 孙鹏[1,2] 刘泽楷 娄群 LI Zhongbang;XIE Mengda;SUN Peng;LIU Zekai;LOU Qun(Criminal Investigation Police University of China,Shenyang 110854,China;Key Laboratory of Forensic Science,Ministry of Justice,Shanghai 200063,China)

机构地区：[1]中国刑事警察学院,沈阳110854 [2]司法部司法鉴定重点实验室,上海200063

出　　处：《刑事技术》2022年第5期441-447,共7页Forensic Science and Technology

基　　金：国家重点研发计划(2017YFC0822204);司法部司法鉴定重点实验室开放课题(KF2012);国家级大学生创新训练计划项目(202010175008);中国刑事警察学院研究生创新能力提升项目(2020YCZD03)。

摘　　要：在视频侦查中,涉案视频的偏色将降低视觉类算法鲁棒性并导致人为认知偏差。然而,现有多数色彩恒常算法在偏色校正过程中的光照估计精度欠佳且实时性较差,导致难以应用于涉案视频的偏色校正。针对上述问题,提出了一种基于局部过曝抑制的降采样白斑算法,算法可用于视频帧或单幅图像的偏色校正。首先,为避免视频帧及图像中过曝像素对光照估计的干扰,基于像素通道分量值对过曝像素进行判定并采用掩模覆盖。随后,通过随机化选取像素的方式对视频帧及图像进行降采样并应用白斑算法,以弱化噪点及杂散噪声对光照估计的影响,同时降低数据量,加快算法运行速度。在标准数据集及自建数据集中的实验结果表明,该算法在采集自多个设备的视频帧及图像中均取得较好的偏色校正结果,在两类数据集中运行速度分别为0.03和0.02 s,相比大多数色彩恒常算法速度优势明显。本文提出的算法可以在采集自多个设备的视频帧或图像中快速执行光照估计并进行色彩校正,算法光照估计精度较高且速度优势明显,可作为涉案偏色视频以及单幅图像的一种校正策略。In video investigation,the crime-related video color deviation will incur the relevant visual algorithm to reduce its robustness and lead to artificial cognitive bias.However,most present algorithms handling color constancy are poor of both illumination estimation accuracy and real-time performance for color cast correction,hence leaving them being difficult to apply into processing videos involved with crimes.To address the above problems,an algorithm is here proposed for downsampling white patches to inhibit the local over-exposed pixels so that the color cast correction can be carried out into a single image or one video frame.For avoiding interference to illumination estimation of the over-exposed pixels in video frames and/or images,those over-exposed pixels are to determine their componential values on the respective pixel channel so as to have a mask coverage be subsequently carried out.The video frames and/or images are afterwards to downsample through selecting pixels randomly.Finally,the white patch algorithm is to apply into weakening the influence of disturbing dots and/or stray noises on illumination estimation,meanwhile reducing the amount of data and speeding up the algorithmic operation.For the dataset of either the standard or the self-built,the built algorithm can deliver better color cast correction in the video frames and images collected from multiple devices,running at the respective 0.03 s and 0.02 s in the two datasets,demonstrating an obviously quicker speed than that from most algorithms of color constancy.The algorithm proposed here is able to quickly perform illumination estimation and color correction in the video frames or images collected from multiple devices,having advantages of high-precision illumination estimation and evident speed.It can be used as a correction strategy for one crime-related color-cast video and a single image.

关 键 词：视频侦查 计算机视觉 偏色 色彩恒常性 光照估计 过曝像素 降采样 白斑算法 

分 类 号：DF793.2[政治法律—诉讼法学]