Digital Signal Processing Reference
In-Depth Information
Figure 10.12. Flow graph of the ridgelet transform on the sphere.
j
th subband [2
j
2
j
+
1
]. We used the default value
B
min
=
16 pixels in our implemen-
tation. Figure 10.14 gives an overview of the organization of the algorithm.
Figure 10.15 shows the backprojection of curvelet coefficients at different scales
and orientations.
,
10.6.3 Pyramidal Curvelet Transform on the Sphere
The CTS is very redundant, which may be a problem for handling huge data sets
such as Planck data (see Section 10.8.2). The redundancy can be reduced by sub-
stituting, in the curvelet transform algorithm, the pyramidal wavelet transform with
the undecimated wavelet transform. The second step, which consists of applying the
Figure 10.13. Ridgelet atoms on the sphere
obtained by reconstruction from a few ridgelet
coefficients at different scales and orienta-
tions. (
See color plates.
)
