Temporally Coded Illumination for Rolling Shutter Motion De-Blurring

Abstract

Rolling shutter image sensors are increasingly used over global shutter sensors due to their lower cost and reduced size. As is well known in the computer vision community, one drawback of rolling shutter sensors is that they introduce geometric distortions, such as skew or wobble, when either the sensor or objects in the scene move. This problem has received a great deal of attention, and robust solutions are now widely available. Less well known is the fact that, when used in conjunction with active illumination (i.e., a flash), rolling shutter images are often motion blurred due to timing issues between the sensor and illuminator. We address this in the context of barcode scanning, where blur significantly limits the motion tolerance of rolling shutter-based devices. Building on past work which uses temporally-coded illumination patterns to improve the invertibility of motion blur, we modulate the illuminator in a particular temporal pattern in order to ensure that the sharp image can be recovered despite spatially-varying blur. Experimentally, we modify a commercial, off-the-shelf scanner to demonstrate an ability to correctly decode a barcode moving faster than the stated motion tolerance.