para2fan() - Image Processing

F = para2fan(P, D) converts
 the parallel-beam data P to the fan-beam data F.
Each column of P contains the parallel-beam sensor
samples at one rotation angle. D is the distance
in pixels from the fan-beam vertex to the center of rotation that
was used to obtain the projections. The sensors are assumed to have a one-pixel spacing. The parallel-beam
rotation angles are assumed to be spaced equally to cover [0,180]
degrees. The calculated fan-beam rotation angles cover [0,360) with
the same spacing as the parallel-beam rotation angles. The calculated
fan-beam 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   ParameterDescription
'FanCoverage'String specifying the range of rotation angles used to
calculate the projection data F.Possible values: {'cycle'} or 'minimal'See ifanbeam for
details.
'FanRotationIncrement'Positive real scalar specifying the rotation angle increment
of the fan-beam projections in degrees.If 'FanCoverage' is 'cycle', 'FanRotationIncrement' must
be a factor of 360.If 'FanRotationIncrement' is
not specified, then it is set to the same spacing as the parallel-beam
rotation angles.
'FanSensorGeometry'String specifying how sensors are positioned.Possible
values:  {'arc'} or  'line' See fanbeam for
details.
'FanSensorSpacing'Positive real scalar specifying the spacing of the fan
beams. Interpretation of the value depends on the setting of 'FanSensorGeometry':If 'FanSensorGeometry' is 'arc',
the value defines the angular spacing in degrees. Default value is
1.If 'FanSensorGeometry' is 'line',
the value defines the linear spacing in pixels. If 'FanSensorSpacing' is
not specified, the default is the smallest value implied by 'ParallelSensorSpacing' such
thatIf 'FanSensorGeometry' is 'arc', 'FanSensorSpacing' is  180/PI*ASIN(PSPACE/D)where PSPACE is
the value of  'ParallelSensorSpacing'.If 'FanSensorGeometry' is 'line', 'FanSensorSpacing' is D*ASIN(PSPACE/D)
'Interpolation'Text string specifying the type of interpolation used
between the parallel-beam and fan-beam data.'nearest' —
Nearest-neighbor{'linear'} —
Linear'spline' — Piecewise
cubic spline'pchip' — Piecewise
cubic Hermite (PCHIP)'v5cubic' —
The cubic interpolation from MATLAB® 5
'ParallelCoverage'Text string specifying the range of rotation.'cycle' --
Parallel data covers 360 degrees{'halfcycle'} —
Parallel data covers 180 degrees
'ParallelSensorSpacing'Positive real scalar specifying the spacing of the parallel-beam
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 'ParallelSensorSpacing' is
not specified, the spacing is assumed to be uniform and is set to
the minimum spacing implied by the fan angles and sampled over the
range implied by the fan angles.
[F, fan_positions, fan_rotation_angles]
= fan2para(...) returns the fan-beam sensor measurement angles in fan_positions,
if 'FanSensorGeometry' is 'arc'.
If 'FanSensorGeometry' is 'line', fan_positions contains
the fan-beam sensor positions along the line
of sensors. fan_rotation_angles contains rotation
angles.

Syntax

F = para2fan(P, D)I = para2fan(..., param1, val1, param2,
val2,...)[F, fan_positions, fan_rotation_angles]
= fan2para(...)

Example

180/PI*ASIN(PSPACE/D)

Output / Return Value

Limitations

Alternatives / See Also

Reference