Integrated Object Detection and Deconvolution
A vision model is a framework for carrying out object detection. (In a
context other than astronomy, feature detection may be a more appropriate
term.) A vision model may be simple e.g. background + object(s)
superimposed, or it may be more sophisticated e.g. involving a multiscale
transform. The benefits of considering carefully the vision model used,
for very fine-tuned work, have been discussed in Bijaoui and Rué
(1995), Rué and Bijaoui (1997), and Starck et al. (1998).
If we know that deconvolution will improve the result, then we have to
integrate deconvolution with our vision model. An integrated algorithm
for doing this is described in Starck (1999).
Fig. 1 (compressed Postscript, 180kB)
shows isophotes of
objects detected using a vision model - multiscale transform with noise
modeling - without deconvolution. ISOCAM (a detector on board the ISO
satellite) was used, and the data collected using the 6 arcsec lens at
6.75 microns. This was a raster observation with 10s integration time,
16 raster positions, and 25 frames per raster position. The non-stationary
noise was modeled using a root-mean-square error map (see Starck et al.,
1999). In the Fig., the isophotes are overplotted on an optical image,
NTT, band V (from ESO's Paranal observatory), in order to identify the
infrared sources. Fig. 2 (compressed
shows the same result, but this time based on vision modeling with
deconvolution. The objects are the same, but the photometry is improved.
It is clearly easier to identify the optical counterparts of the
- A. Bijaoui and F. Rué, "A multiscale vision model adapted
to astronomical images", Signal Processing, 46, 229-243, 1995.
- F. Rué and A. Bijaoui, "A multiscale vision model to analyse
field astronomical images", Experimental Astronomy, 7, 129-160, 1997.
- J.L. Starck, H. Aussel, D. Elbaz, D. Fadda and C. Cesarsky,
"Faint source detection in ISOCAM images with PRETI", Astronomy and
Astrophysics, submitted, 1999.
- J.L. Starck, "A combined approach for detection and deconvolution",
Technical Report, CEA, Jan. 1999.
- J.L. Starck, F. Murtagh and A. Bijaoui, Image and Data Analysis: The
Multiscale Approach, Cambridge University Press, 1998.