07/12/2007 The picture below shows the result of modeling galaxy profiles with the latest EFIGI version of SExtractor on a set of 45 galaxies with negative spirality indices, randomly chosen in the PGC-1.3 g-band sample (click the picture to zoom).
Galaxies are modeled as the sum of a bulge, a disk, a bar and spiral arms (19 parameters) convolved with the local PSF. There are still some difficulties to fit the inner parts of the spiral structure. No cleaning with nfigi has yet been applied to the images, and only the largest objects were fitted. The fitting residuals are shown below (contrast doubled).