In the present paper we examined the multispectral analysis of astronomical images as a particular BSS case. Even if the cocktail party model is not realistic for processing celestial images, we showed that the application of different BSS algorithms gives quite similar decompositions.
From the physical point of view, the resulting sources correspond mainly to real phenomena. These separations can provide useful information for astrophysicists.
We experimented with different BSSs. Some further improvements in the methods may be possible. For our application the main difficulties do not depend on these technical points but on the basic Eq. (1). The model required:
Although real multispectral observations do not exactly satisfy these conditions, BSS can still be considered as an interesting exploratory tool, which can suggest a new analysis approach to the user, as we have seen above. Its use is well adapted to data mining.
We plan to apply these tools to a set of observations of typical astronomical sources, with images taken through many filters, and to process with BSS tools the several hundred of monochromatic images provided by astronomical spectroimagers.
Acknowledgements
The authors thank STScI for the use of the HST archive, Dr. J.F. Cardoso for the use of the original SOBI and JADE programs, Dr. A. Hyvärinen for the use of FastICA program, Dr. J.M. Nuzillard for his help in SOBI adaptations, and Dr. G. Lelièvre and G. Wlérick for comments on 3C 120 results. The authors thank also an anonymous referee for his comments that have contributed to the improvement of the final version.
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