Improved LUT-Based Image Warping for Video Cameras

Abstract

Image warping is usually used to perform real-time geometry transformation for video cameras. Several existing look-up table (LUT)-based algorithms achieve real-time performance, but the size of LUT is large and it has to be stored into off-chip memory. To reduce latency and bandwidth requirements due to using off-chip memory, this paper proposes an improved LUT (ILUT) scheme which compresses the LUT small enough that it can be stored in on-chip memory. Firstly, a one-stop transformation is adopted instead of several stages of on-line calculation. Then, the memory size of LUT is reduced by utilizing the similarity of neighbor coordinates and the symmetric characteristic of some image warping. Moreover, an elaborate pipeline hardware structure, cooperating with a novel 25-point interpolation algorithm, is proposed to accelerate the system and save further usage of memory. The proposed system is implemented by a field-programmable gate array-based platform. Two different examples show that the proposed ILUT achieves a real-time performance with small memory usage and low system requirements.