Chiu Shih-Hsuan, Lu Chuan-Pin, Wen Che-Yen
Department of Polymer Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.
J Forensic Sci. 2006 Sep;51(5):1115-9. doi: 10.1111/j.1556-4029.2006.00205.x.
Closed-circuit television (CCTV) security systems have been widely used in banks, convenience stores, and other facilities. They are useful to deter crime and depict criminal activity. However, CCTV cameras that provide an overview of a monitored region can be useful for criminal investigation but sometimes can also be used for object identification (e.g., vehicle numbers, persons, etc.). In this paper, we propose a framework for improving the image quality of CCTV security systems. This framework is based upon motion detection technology. There are two cameras in the framework: one camera (camera A) is fixed focus with a zoom lens for moving-object detection, and the other one (camera B) is variable focus with an auto-zoom lens to capture higher resolution images of the objects of interest. When camera A detects a moving object in the monitored area, camera B, driven by an auto-zoom focus control algorithm, will take a higher resolution image of the object of interest. Experimental results show that the proposed framework can improve the likelihood that images obtained from stationary unattended CCTV cameras are sufficient to enable law enforcement officials to identify suspects and other objects of interest.
闭路电视（CCTV）安全系统已在银行、便利店及其他场所广泛应用。它们有助于威慑犯罪并记录犯罪活动。然而，提供监控区域全景的CCTV摄像头虽对刑事调查有用，但有时也会被用于物体识别（如车牌号、人员等）。在本文中，我们提出了一个用于提高CCTV安全系统图像质量的框架。该框架基于运动检测技术。框架中有两个摄像头：一个摄像头（摄像头A）是定焦且带有变焦镜头，用于检测移动物体；另一个（摄像头B）是可变焦且带有自动变焦镜头，用于捕捉感兴趣物体的高分辨率图像。当摄像头A在监控区域检测到移动物体时，由自动变焦聚焦控制算法驱动的摄像头B将拍摄感兴趣物体的高分辨率图像。实验结果表明，所提出的框架能够提高从固定的无人值守CCTV摄像头获取的图像足以让执法人员识别嫌疑人及其他感兴趣物体的可能性。
