Real-time noise reduction for sonar video image using recursive filtering

The forward-looking imaging sonar is a prospective solution for underwater visual surveying because it allows long-range visibility in turbid water, and provides a high frame rate. However, the acoustic images are degraded by speckle noise. In this paper, we propose an algorithm to reduce the noise in a series of acoustic image frames obtained by using a forward-looking imaging sonar. The time-series model of the acoustic images are developed for predicting the changes in pixel coordinates. Also, the Kalman filter estimates the noise-reduced pixels of the images based on the acoustic image model. This recursive treatment is suitable for the successive image frames.