Selecting the Optimal Focus Measure for Autofocusing and Depth-From-Focus
IEEE Transactions on Pattern Analysis and Machine Intelligence
W4: Real-Time Surveillance of People and Their Activities
IEEE Transactions on Pattern Analysis and Machine Intelligence
Active Computer Vision by Cooperative Focus and Stereo
Active Computer Vision by Cooperative Focus and Stereo
Digital Imaging with Extreme Zoom: System Design and Image Restoration
ICVS '06 Proceedings of the Fourth IEEE International Conference on Computer Vision Systems
A Bayes-spectral-entropy-based measure of camera focus using a discrete cosine transform
Pattern Recognition Letters
New autofocusing technique using the frequency selective weighted median filter for video cameras
IEEE Transactions on Consumer Electronics
IEEE Transactions on Consumer Electronics
Implementation of a passive automatic focusing algorithm for digital still camera
IEEE Transactions on Consumer Electronics
Hi-index | 0.00 |
Auto-focusing is an indispensable function for imaging systems used in surveillance and object tracking. In this paper, we conduct a study of an image-based passive auto-focusing control for high magnification (50×) systems using off-the-shelf telescopes and digital camcorders with applications to long range near-ground surveillance and face tracking. Considering both speed of convergence and robustness to image degradations induced by high system magnifications and long observation distances, we introduce an auto-focusing mechanism suitable for such applications, including hardware design and algorithm development. We focus on the derivation of the transition criteria following maximum likelihood (ML) estimation for the selection of adaptive step sizes and the use of sharpness measures for the proper evaluation of high magnification images. The efficiency of the proposed system is demonstrated in real-time auto-focusing and tracking of faces from distances of 50m~300m.