Feature extraction from solar images using wavelet transform: Image cleaning for applications to solar astrolabe experiment

Good edge extraction from temporal series of solar images is fundamental in the solar astrolabe experiment. Noise and spots in images cause however, d ifficulties to extract an accurate solar edge. We present in this paper a n ew image-processing method which solves this problem and thus improves the characteristics of the solar astrolabe experiment. The method is based upon the use of wavelet transform in the solar image analysis. It is developed to remove image defects (parasite spots) and noise without reducing image r esolution. Solar images obtained at Calern Observatory astrolabe (France) a re then processed using this method. Solar edges of these images are extrac ted and trajectories reconstructed.