Noise-reducing Sound Capture Based on Exposure-time of Still Camera
Proceedings of the ICA congress
A visual microphone has been proposed to capture the distant sound. This microphone captures the sound from high frame-rate video by using the pixel difference. It is expected to be applied in surveillance cameras because it is robust to be affected by the sound distance. However, this capturing method is unpractical due to expensive-equipment requirement. In this paper, we attempt to realize inexpensive visual microphones by using a still camera with a CMOS image sensor. A CMOS image sensor
... MOS image sensor shoots the image including rolling-shutter distortion. An image shot with the CMOS sensor has short time displacement information because the sensor sequentially writes image to each line. Therefore, it is possible to capture sound from an image without the high frame-rate video in case of acoustic signals can be extracted from the short time displacement information included in the image. However, lower frequency noise is included in the captured sound using the sensor due to the inclination and distortion of the object to be photographed. This noise depends on the exposure-time of the sensor. We thus propose a noise reducing method for the captured sound by a digital filter considering the exposure-time of the CMOS image sensor. Experimental results show that the proposed method can reduce the noise compared with the original captured sound.