A novel method for simultaneous acquisition of visible and near-infrared light using a coded infrared-cut filter

Abstract

This paper presents a novel image sensing method to enhance the sensitivity of a camera. Most image sensors used in commercial digital cameras are sensitive for both visible and infrared light. An IR-cut filter, that obstructs the infrared component of natural light, is used in such cameras to realize a similar color reproduction as for the human visual system. However, recent studies have shown that the near infrared light contains useful information to further enhance the visible image. This paper introduces a new sensing method by using a coded IR-cut filter to enable simultaneous capturing of NIR and visible light on a single image sensor. The coded IR-cut filter lets a fraction of the near infrared light pass and blocks out the rest. Both visible and near infrared light images can be separated from the sensor output when taking the diffraction of the NIR light into account. Experiments, using a synthesized image sensor output, demonstrate the validity of the method.