Lan Hsiao-Chin, Wu Mount-Learn, Yeatman Eric M
Department of Electrical and Electronic Engineering, Imperial College London, London, SW7 2AZ, UK.
Opt Express. 2009 Dec 7;17(25):22992-3002. doi: 10.1364/OE.17.022992.
A sub-pixel image shifter is presented, for use in enhancing the spatial resolution of digital image sensors by combining multiple displaced sub-images using a super-resolution (SR) algorithm. The device uses the walk-off phenomenon in birefringent crystals to separate images with opposite polarizations by a sub-pixel displacement. A liquid crystal (LC) waveplate plus a polarizer can then select the specific image to be exposed, with fast, non-mechanical control. This cascaded device, comprising two sapphire crystals, two LCs, and a single polarizer, is capable of 2-dimensional image shift with displacements of 0.5 pixels. The experimental results show that the image registration stability can be precisely controlled within 0.05 pixels and the contrast transfer function ratio of the SR image is enhanced by up to 1.36 times compared to the original captured image. Moreover, based on the fast transition time of LCs, the displaced sub-images can be recorded in video form with a frame rate of 40 fps.
提出了一种亚像素图像移位器，用于通过使用超分辨率（SR）算法组合多个移位的子图像来提高数字图像传感器的空间分辨率。该装置利用双折射晶体中的离散现象，通过亚像素位移来分离具有相反偏振的图像。然后，液晶（LC）波片加上偏振器可以通过快速、非机械控制来选择要曝光的特定图像。这种级联装置由两个蓝宝石晶体、两个液晶和一个偏振器组成，能够进行二维图像移位，位移量为0.5像素。实验结果表明，图像配准稳定性可以精确控制在0.05像素以内，与原始捕获图像相比，SR图像的对比度传递函数比提高了1.36倍。此外，基于液晶的快速转换时间，移位的子图像可以以40帧/秒的帧率以视频形式记录。
