Convert parallelbeam projections to fanbeam
F = para2fan(P, D)
I = para2fan(..., param1, val1, param2,
val2,...)
[F, fan_positions, fan_rotation_angles]
= fan2para(...)
F = para2fan(P, D)
converts
the parallelbeam data P
to the fanbeam data F
.
Each column of P
contains the parallelbeam sensor
samples at one rotation angle. D
is the distance
in pixels from the fanbeam vertex to the center of rotation that
was used to obtain the projections.
The sensors are assumed to have a onepixel spacing. The parallelbeam rotation angles are assumed to be spaced equally to cover [0,180] degrees. The calculated fanbeam rotation angles cover [0,360) with the same spacing as the parallelbeam rotation angles. The calculated fanbeam angles are equally spaced with the spacing set to the smallest angle implied by the sensor spacing.
I = para2fan(..., param1, val1, param2,
val2,...)
specifies parameters that control various aspects
of the para2fan
conversion. Parameter names can
be abbreviated, and case does not matter. Default values are enclosed
in braces like this: {default}. Parameters include
Parameter  Description 

 Range of rotation angles used to calculate the projection data. Possible values: See 
 Positive real scalar specifying the rotation angle increment of the fanbeam projections in degrees. If If 
 Positioning of sensors, specified as either of the following values:
See 
 Positive real scalar specifying the spacing of the fan
beams. Interpretation of the value depends on the setting of If If If If 180/PI*ASIN(PSPACE/D) where If D*ASIN(PSPACE/D) 
 Type of interpolation used between the parallelbeam and fanbeam data, specified as one of the following values:

 Range of rotation, specified as one of the following values:

 Positive real scalar specifying the spacing of the parallelbeam sensors in pixels. The range of sensor locations is implied by the range of fan angles and is given by [D*sin(min(FAN_ANGLES)),D*sin(max(FAN_ANGLES))] If 
[F, fan_positions, fan_rotation_angles]
= fan2para(...)
returns the fanbeam sensor measurement angles in fan_positions
,
if 'FanSensorGeometry'
is 'arc'
.
If 'FanSensorGeometry
' is 'line'
, fan_positions
contains
the fanbeam sensor positions along the line
of sensors. fan_rotation_angles
contains rotation
angles.
P
and D
can be double
or single
,
and must be nonsparse. The other numeric input arguments must be double
.
The output arguments are double
.