![\begin{figure}
\par\includegraphics[width=8.8cm,clip]{H3453F6.ps}
\end{figure}](/articles/aa/full/2002/39/aah3453/Timg66.gif) |
Figure A.1:
Upper left: typical ISSA map
with a large scale gradient. Upper right: amplitude of the
Fourier Transform of the image on the left. The cross seen here is
produced by the left-right and top-bottom
flux difference in the image. Lower right: amplitude of the Fourier Transform
of the image apodized with a cosine function to minimize the left-right and top-bottom
discontinuities. Lower left: power spectrum of the original image (solid line)
and of the apodized image (red line). The power spectrum computed with the Median method
is also shown (dotted line). It follows almost perfectly the power spectrum of
the apodized image. |