Paper Info
Title
Online Lens Motion Smoothing for Video Autofocus
Abstract
Autofocus (AF) is the process of moving the camera's lens such that desired scene content is in focus. AF for single image capture is a well-studied research topic and most modern cameras have hardware support that allows quick lens movements to optimize image sharpness. How to best perform AF for video is less clear. Conventional wisdom would suggest that each temporal frame should be as sharp as possible. However, unlike single image capture, the effects of the lens movement is visible in the captured video. As a result, there are two parameters to consider in AF for video: sharpness and lens movement. In this paper, we show that users preferred videos with smooth lens movement, even if it results in less overall sharpness. Based on this observation, we propose two novel AF algorithms for video that strive for both smooth lens movement and sharp scene content. Specifically, we introduce (1) a bidirectional long short-term memory (BLSTM) module trained on smooth lens trajectories and (2) a simple weighted moving average (WMA) method that factors in prior lens motion. Both of these methods have demonstrated excellent results in terms of reducing lens movements (up to 64% reduction) without greatly affecting the sharpness (less than 5.2% change in sharpness). Moreover, videos produced using our methods are more preferred by users over conventional AF that aims only for maximizing sharpness.
Year
DOI
Venue
2020
10.1109/WACV45572.2020.9093558
2020 IEEE Winter Conference on Applications of Computer Vision (WACV)
Keywords
DocType
ISSN
online lens motion smoothing,video autofocus,camera lens,scene content,single image capture,image sharpness,captured video,smooth lens movement,sharp scene content,smooth lens trajectories,simple weighted moving average method,lens movements,bidirectional long short-term memory
Conference
2472-6737
ISBN
Citations 
PageRank 
978-1-7281-6554-7
0
0.34
References 
Authors
6
2
Name
Order
Citations
PageRank
Abdullah Abuolaim163.18
Michael S. Brown22122129.13