Two Digital Filtering Methods and the Spiral Structure of the M 31 Galaxy
Image enhancement techniques are capable of greatly improving the image quality. Many methods have been envolved to diminish the noise by smoothing or some kind of low-frequency filtering, and there are a number of restoration methods by high-frequency filtering (Bijaoui, 1979). In this paper we shall examine two both simple and useful methods and some of their applications. For our purposes we used a Joyce Loebl microaensitometer and a PDP 11–34 computer of the Rozhen National Astronomical Observatory (Kovachev et al., 1984). The methods described are included in our image processing software (Georgiev, 1986).
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