Restoring chopped and nodded images by tight frames

Abstract

In infrared astronomy, the observed chopped and nodded image g can be viewed as the image obtained by passing the true image f through a highpass filter. Here we propose an iterative restoration algorithm by building up a tight frame wavelet system from a multiresolution analysis that has the highpass filter as one of the wavelet filters. To recover f, the low frequency information of f hidden in g is unfolded by a wavelet decomposition and reconstruction algorithm and combined with the given high frequency information in g. The main advantage of using our method to restore chopped and nodded images is that there are fewer artifacts as compared to the well-known projected Landweber method. Also the noise in the restored image is significantly reduced. Simulated and real images are tested to illustrate the efficiency of our method. Here, we briefly describe the main ideas of our recent paper1 and the details can be found there.