Suppressing rolling-shutter distortion of CMOS image sensors by motion vector detection

This paper focuses on the rolling shutter distortion of CMOS image sensor coming from its unique readout mechanism as the main cause for image degradation when there are fast-moving objects. This paper proposes a post image processing scheme based on motion vector detection to suppress the rolling shutter distortion. Motion vector detection is performed based on an optical flow method at a reasonable computational complexity. A practical implementation scheme is also described.

I. Introduction

Since solid-state image sensors replaced films in the consumer electronics market, more and more digital gadgets such as cellular phones and PDA's are increasingly equipped with digital camera function. Image sensor, which converts photons into electrons via photoelectric effect, consists of photodiodes or phototransistors as light-sensing area and peripheral circuitry to control the signal read-out. Image sensors are classified into CCD image sensor and CMOS image sensor (CIS). While CCD can store charges like a memory and can transfer them by means of controlling gate voltages [1], MOSFET's in CIS can only transfer charges from photodiodes to readout circuitry without storing them.