改进YOLOv4算法的复杂视觉场景行人检测方法

复杂视觉场景下存在过暗或者过曝的光照、恶劣的天气、严重遮挡、行人尺寸差别大以及图像模糊等问题，大大增加了行人检测的难度。因此，针对复杂视觉场景下行人检测准确度低、漏检严重的问题，提出了改进的YOLOv4算法以增强复杂视觉场景下的行人检测效果。首先，构建复杂视觉场景下的行人数据集。然后，在主干网中加入混合空洞卷积，提高网络对行人特征的提取能力。最后，提出空间锯齿空洞卷积结构，代替空间金字塔池化结构，获取更多细节特征。实验表明，在本文构建的行人数据集上，改进后的 YOLOv4算法的平均精度（average precision，AP）达到了90.08%，相比原YOLOv4算法提高了7.2%，对数平均漏检率（log-average miss rate，LAMR）降低了13.69%。

An improved YOLOv4 algorithm for pedestrian detection in complex visual scenes

At present, the difficulty of pedestrian detection has been dramatically increased because of some problems, such as the dark or exposed illumination, bad weather, serious occlusion, large difference size of pedestrians and blurred images in complex visual scenes.Therefore, an improved YOLOv4 algorithm was proposed, which improved the detection performance of pedestrian detection in complex visual scenes, aiming at the problems of low accuracy and highly missed detection rate.Firstly, the self-annotation data set pedetrian were constructed.Secondly, the hybrid dilated convolution (HDC) was added into the backbone network to improve the ability of pedestrian feature extraction.Finally, in order to obtain more detailed feature, the spatial jagged dilated convolution (SJDC) structure was proposed to replace the spatial pyramid pooling structure.The experimental results show that the average precision (AP) of the proposed algorithm can achieve 90.08%.The proposed algorithm can substantially improve AP by 7.2%, and the log-average miss rate (LAMR) reduce by 13.69% compared with the original YOLOv4 algorithm.