Fan-beam transform
uses name-value pairs to specify the rotation increment and sensor
spacing.F
= fanbeam(I
,D
,Name,Value
)
[
returns the location of fan-beam sensors in
F
,fan_sensor_positions
,fan_rotation_angles
]
= fanbeam(___)fan_sensor_positions
and the rotation
angles where the fan-beam projections are calculated in
fan_rotation_angles
.
As a guideline, try making D
a few pixels larger than
half the image diagonal dimension, calculated as follows.
sqrt(size(I,1)^2 + size(I,2)^2)
The values returned in F
are a numerical approximation of
the fan-beam projections. The algorithm depends on the Radon transform,
interpolated to the fan-beam geometry. The results vary depending on the
parameters used. You can expect more accurate results when the image is
larger, D
is larger, and for points closer to the middle
of the image, away from the edges.
[1] Kak, A.C., & Slaney, M., Principles of Computerized Tomographic Imaging, IEEE Press, NY, 1988, pp. 92-93.