class ProjectionSimulator(object):
"""
Simple class to simulate parallel-beam x-ray projections of a phantom.
Since the projections are usually obtained from a phantom, it's preferred
(for convenience) to match the number of bins to the pixel size of the
phantom. Otherwise, the phantom needs to be resized before being projected.
If the reconstruction is performed using a binary system matrix, that
matrix can be evaluated during the projection.
"""
def __init__(self, views, nrBins, phantom=None, start=0, stop=180):
self.__phantom = phantom
self.__nrBins = nrBins
self._views = views
self._start = start
self._stop = stop
self._angleInc = (stop-start)/float(views)
self.__projections = None
@property
def loadSize(self):
return self._views
@property
def phantom(self):
return self.__phantom
@property
def projections(self):
return self.__projections
@property
def views(self):
return self._views
def initProjections(self):
""" Initialize the projections object. """
self.__projections = Projections(self._views, self.__nrBins)
def projectAll(self, start=0, stop=180):
"""
Simulate a parallel-beam x-ray projection by summing up the phantom
data matrix column wise, yielding a sinogram line.
To this end, the number of bins (that the phantom is projected onto)
and the phantom pixel size should be equal. Otherwise, the phantom
needs to be reshaped.
"""
if self.readyForProjecting():
for a in range(0, self._views):
if a%25==0:
print "Projecting view " + str(a)
self.computeOne(a)
def computeOne(self, view):
"""
Helper function. Performs a single projection.
Required in ProjectionSimulatorHandler.process() to signal progress
after a single projection.
:param view | int
"""
rotPhantom = self.phantom.rotate(self._start - view*self._angleInc)
self.__projections.project(view, rotPhantom)
def ready(self):
"""
Convenience method for checking prerequisites for projecting.
:return isReady | bool
"""
if self.phantom is None or self.projections is None:
return False
if self.__nrBins != self.phantom.size:
pass #TODO resize phantom
return True
