title: Non-mechanical sub-pixel image shifter for acquiring super-resolution digital images.
abstract: 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.
authors.affiliation: Department of Electrical and Electronic Engineering, Imperial College London, London, SW7 2AZ, UK.
authors.forename: Hsiao-Chin
authors.initials: HC
authors.lastname: Lan
authors.forename: Mount-Learn
authors.initials: ML
authors.lastname: Wu
authors.forename: Eric M
authors.initials: EM
authors.lastname: Yeatman
mesh_terms: D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007089:Image Enhancement / Q000295:instrumentation*; D050866:Liquid Crystals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D013382:Subtraction Technique / Q000295:instrumentation*