real-time full frame view of surveillance camera provides integral visual information of scene. high definition imaging and zooming are widely adopted when observers want to capture more detail information of targets. the optical zooming can provide high zoom ratio detail images of target as well as maintain imaging definition, however, it fails to obtain full view of scene when zoomed, and the field of observation decreases to region of target. digital zooming is an effective approach to keep the balance between imaging field and visual detail information. this paper presents a method of stepless zooming for digital video camera which could be widely used in autonomous pan, tilt and zoom surveillance system. in view of hardware resources and algorithm realizability, an optimized zooming processing structure is proposed. according to input zoom ratio parameter, it can extract pixels of region of interest adaptively and display with original imaging size by mapping and interpolation algorithms. experimental results indicate that the stepless zooming method can be capable of achieving 1080p high definition imaging and 30 frame/s video capture. © 2016 spie.