Digital Techniques for Noise Reduction in APT NOAA Satellite Images

Noise reduction filters were tested using NOAA satellite images. The best results, in terms of noise suppression and blur attenuation are obtained by two kinds of digital filtering techniques: weighted median filter with central pixel weight = 3 and decision threshold =12; and extremal filter with maximum number of extremal pixels =3. The other kinds of techniques show a nonuniform behavior, mainly in terms of noise pixel leaving. Both the filters were used in iterative mode: the weighted median filter needs fewer iterations to reach a stable condition than the extremal filter. However the mean computing time per iteration of the extremal filter is 30% less than the weighted filter time.