Ejemplo n.º 1
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 def _contruct_ilang_model(self): 
     self.ilang_model   = ModelRigidSSD('RigidSSD')
     self.graph         = ProbabilisticGraphicalModel(['target','source','transformation']) 
     self.graph.set_nodes_given(['target','source'],True) 
     self.graph.set_node_value('source',self.source.get_data())
     self.graph.set_node_value('target',self.target.get_data())
     self.graph.set_node_value('transformation',numpy.zeros((1,6)))
     self.graph.add_dependence(self.ilang_model,{'target':'target','source':'source','transformation':'transformation'}) 
     self.sampler       = Sampler(self.graph) 
Ejemplo n.º 2
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    def __make_graph(self):
        self.ilang_model = SSD_ilang()
        # The following is an alternative use of ilang models: define the log_p and gradient functions here in order to have access to
        # the local variables.
        self.ilang_model.log_conditional_probability_transformation = self.__P
        self.ilang_model.log_conditional_probability_gradient_transformation = self.__G

        self.ilang_graph = ProbabilisticGraphicalModel(
            ['source', 'target', 'transformation', 'sigma'])
        self.ilang_graph.set_nodes_given(['sigma', 'source', 'target'], True)
        self.ilang_graph.add_dependence(
            self.ilang_model, {
                'source': 'source',
                'target': 'target',
                'sigma': 'sigma',
                'transformation': 'transformation'
            })
        self.ilang_sampler = Sampler(self.ilang_graph)
Ejemplo n.º 3
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 def _contruct_ilang_model(self): 
     self.ilang_model   = ModelRigidSSD('RigidSSD')
     self.graph         = ProbabilisticGraphicalModel(['target','source','transformation']) 
     self.graph.set_nodes_given(['target','source'],True) 
     self.graph.set_node_value('source',self.source.get_data())
     self.graph.set_node_value('target',self.target.get_data())
     self.graph.set_node_value('transformation',numpy.zeros((1,6)))
     self.graph.add_dependence(self.ilang_model,{'target':'target','source':'source','transformation':'transformation'}) 
     self.sampler       = Sampler(self.graph) 
Ejemplo n.º 4
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 def __make_graph(self):
     self.ilang_graph = ProbabilisticGraphicalModel()
     for i in range(len(self.__images)):
         self.ilang_graph.add_node('im_%d' % i)
         self.ilang_graph.set_nodes_given([
             'im_%d' % i,
         ], True)
     for i in range(len(self.__images) - 1):
         self.ilang_graph.add_nodes(['sigma_%d' % i, 'T_%d' % i])
         self.ilang_graph.set_nodes_given([
             'sigma_%d' % i,
         ], True)
         model = SSD_ilang('SSD_%d' % i)
         self.ilang_graph.add_dependence(
             model, {
                 'sigma': 'sigma_%d' % i,
                 'transformation': 'T_%d' % i,
                 'source': 'im_%d' % i,
                 'target': 'im_%d' % (i + 1)
             })
     self.ilang_sampler = Sampler(self.ilang_graph)
Ejemplo n.º 5
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    def __make_graph(self):
        self.ilang_model = SSD_ilang()
        # The following is an alternative use of ilang models: define the log_p and gradient functions here in order to have access to
        # the local variables.
        self.ilang_model.log_conditional_probability_transformation = self.__P
        self.ilang_model.log_conditional_probability_gradient_transformation = self.__G

        self.ilang_graph = ProbabilisticGraphicalModel(["source", "target", "transformation", "sigma"])
        self.ilang_graph.set_nodes_given(["sigma", "source", "target"], True)
        self.ilang_graph.add_dependence(
            self.ilang_model,
            {"source": "source", "target": "target", "sigma": "sigma", "transformation": "transformation"},
        )
        self.ilang_sampler = Sampler(self.ilang_graph)
Ejemplo n.º 6
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 def __make_graph(self):
     self.ilang_graph = ProbabilisticGraphicalModel()
     self.ilang_graph.add_node("template")
     for i in range(len(self.__images)):
         self.ilang_graph.add_node("im_%d" % i)
         self.ilang_graph.set_nodes_given(["im_%d" % i], True)
     for i in range(len(self.__images)):
         self.ilang_graph.add_nodes(["sigma_%d" % i, "T_%d" % i])
         self.ilang_graph.set_nodes_given(["sigma_%d" % i], True)
         model = SSD_ilang("SSD_%d" % i)
         self.ilang_graph.add_dependence(
             model,
             {"sigma": "sigma_%d" % i, "transformation": "T_%d" % i, "source": "im_%d" % i, "target": "template"},
         )
     self.ilang_sampler = Sampler(self.ilang_graph)
Ejemplo n.º 7
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class Registration_N_Images():
    def __init__(self, images):
        self.__images = images
        self.__make_graph()

    def set_transformation(self, tr):
        pass

    def set_cost_function(self, cost):
        pass

    def register(self):
        pass

    def __make_graph(self):
        self.ilang_graph = ProbabilisticGraphicalModel()
        self.ilang_graph.add_node('template')
        for i in range(len(self.__images)):
            self.ilang_graph.add_node('im_%d' % i)
            self.ilang_graph.set_nodes_given([
                'im_%d' % i,
            ], True)
        for i in range(len(self.__images)):
            self.ilang_graph.add_nodes(['sigma_%d' % i, 'T_%d' % i])
            self.ilang_graph.set_nodes_given([
                'sigma_%d' % i,
            ], True)
            model = SSD_ilang('SSD_%d' % i)
            self.ilang_graph.add_dependence(
                model, {
                    'sigma': 'sigma_%d' % i,
                    'transformation': 'T_%d' % i,
                    'source': 'im_%d' % i,
                    'target': 'template'
                })
        self.ilang_sampler = Sampler(self.ilang_graph)

    def _repr_html_(self):
        return self.ilang_graph._repr_html_()

    def __repr__(self):
        return "Registration of N images. "
Ejemplo n.º 8
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class Registration_Two_Images(object):
    def __init__(self,
                 source=None,
                 target=None,
                 degrees_of_freedom=3,
                 sigma=DEFAULT_SIGMA,
                 initial_transformation=None):
        self.set_source(source)
        self.set_target(target)
        self.set_sigma(sigma)
        self.__make_graph()
        if initial_transformation == None:
            self.set_transformation(numpy.zeros(degrees_of_freedom))
        else:
            self.set_transformation(initial_transformation)

    def __make_graph(self):
        self.ilang_model = SSD_ilang()
        # The following is an alternative use of ilang models: define the log_p and gradient functions here in order to have access to
        # the local variables.
        self.ilang_model.log_conditional_probability_transformation = self.__P
        self.ilang_model.log_conditional_probability_gradient_transformation = self.__G

        self.ilang_graph = ProbabilisticGraphicalModel(
            ['source', 'target', 'transformation', 'sigma'])
        self.ilang_graph.set_nodes_given(['sigma', 'source', 'target'], True)
        self.ilang_graph.add_dependence(
            self.ilang_model, {
                'source': 'source',
                'target': 'target',
                'sigma': 'sigma',
                'transformation': 'transformation'
            })
        self.ilang_sampler = Sampler(self.ilang_graph)

    def __set_space(self):
        # make sure that the images are in the same space
        if self.source.space != self.target.space:
            raise "Source [%s] and Target [%s] must be in the same space" % (
                source.space, target.space)
        self.space = self.source.space

    def set_transformation(self, tr):
        self.__transformation = tr

    def __get_transformation(self):
        return self.__transformation

    def set_cost_function(self, cost):
        pass

    def __initialize_registration(self,
                                  optimization_method='QuasiNewton_L_BFGS_B',
                                  n_points=DEFAULT_N_POINTS):
        self.ilang_graph.set_node_value('source', self.source.data)
        self.ilang_graph.set_node_value('target', self.target.data)
        self.ilang_graph.set_node_value('sigma', self.sigma)

        if n_points == None:
            n_points = self.target.shape
        self.grid = self.target.get_world_grid(n_points)
        self.resampled_target = self.target.compute_resample_on_grid(self.grid)

        self.ilang_sampler.set_node_sampling_method_manual(
            'transformation', optimization_method)

    def register(self,
                 optimization_method='GradientAscent',
                 iterations=DEFAULT_N_ITER,
                 n_points=DEFAULT_N_POINTS):
        self.__initialize_registration(optimization_method, n_points)
        self.ilang_graph.set_node_value('transformation', self.transformation)
        self.ilang_sampler.sample(iterations)
        self.transformation = self.ilang_graph.get_node_value('transformation')

    def set_source(self, source):
        self.source = source
        if hasattr(self, 'target'):
            self.__set_space()

    def set_target(self, target):
        self.target = target
        if hasattr(self, 'source'):
            self.__set_space()

    def set_sigma(self, sigma):
        self.sigma = sigma

    def get_result(self):
        result = self.source.copy()
        result.transform(self.get_transformation_matrix())
        return result

    def get_transformation_matrix(self):
        #rot = self.__transformation[0:3]
        #tra = self.__transformation[3:6]
        tra = self.__transformation
        return Transform_Translation(
            tra, self.space, self.space)  #FIXME: rotation and translation

    def display(self):
        D = MultipleVolumesNiftyCore(
            [self.source, self.target,
             self.get_result()])
        #D = MultipleVolumes([self.source, self.target])
        return D

    def __G(self, transformation):
        #        print "Transformation: ", transformation
        #rot = transformation[0:3]
        #tra = transformation[3:6]
        tra = transformation
        T = Transform_Translation(tra, self.space,
                                  self.space)  #FIXME: rotation and translation
        re_s = self.source.compute_resample_on_grid(
            self.grid, affine_grid_to_world=T)  #FIXME: memoize
        gr_s = self.source.compute_gradient_on_grid(self.grid,
                                                    affine_grid_to_world=T)
        re_t = self.resampled_target
        G_tra0 = (re_t.data - re_t.data * gr_s[0]).sum()
        G_tra1 = (re_t.data - re_t.data * gr_s[1]).sum()
        G_tra2 = (re_t.data - re_t.data * gr_s[2]).sum()
        G_tra = [G_tra0, G_tra1, G_tra2]
        G = numpy.asarray([G_tra[0], G_tra[1], G_tra[2]]) / self.sigma
        #        print "gradient:       ", G
        #        print "log_likelihood: ", self.__P(transformation)
        return G

    def __P(self, transformation):
        # FIXME: memoize (now image is resampled to compute log_p and the gradient)
        #print transformation
        #rot = transformation[0:3]
        #tra = transformation[3:6]
        tra = transformation
        T = Transform_Translation(tra, self.space,
                                  self.space)  #FIXME: rotation and translation
        resampled_source = self.source.compute_resample_on_grid(
            self.grid, affine_grid_to_world=T)
        P = -numpy.linalg.norm(resampled_source.data - self.resampled_target.
                               data) / self.sigma  #FIXME: verify
        #        print "log_likelihood: ", P
        return P

    def _repr_html_(self):
        #return self.ilang_graph._repr_html_()
        return self.display()._repr_html_()

    def __repr__(self):
        return "Registration of 2 images."

    transformation = property(__get_transformation, set_transformation)
Ejemplo n.º 9
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class RigidTransformationSSD(): 
    def __init__(self,target,source): 
        self.target = target 
        self.source = source 
        self._resampled_source_cache = None 
        self._resampled_source_need_update = True
        self._contruct_ilang_model()
        self._set_transformation(numpy.zeros((1,6))) 
        
    def _contruct_ilang_model(self): 
        self.ilang_model   = ModelRigidSSD('RigidSSD')
        self.graph         = ProbabilisticGraphicalModel(['target','source','transformation']) 
        self.graph.set_nodes_given(['target','source'],True) 
        self.graph.set_node_value('source',self.source.get_data())
        self.graph.set_node_value('target',self.target.get_data())
        self.graph.set_node_value('transformation',numpy.zeros((1,6)))
        self.graph.add_dependence(self.ilang_model,{'target':'target','source':'source','transformation':'transformation'}) 
        self.sampler       = Sampler(self.graph) 

    def _set_transformation(self,transformation):
        self.graph.set_node_value('transformation',transformation) 
        self._resampled_source_need_update = True 
    
    def _get_transformation(self): 
        return self.graph.get_node_value('transformation')
      
    def estimate_transformation(self,method=None,iterations=30000,trace=True,parameters=None, display_progress=True): 
        if method!=None: 
            self.sampler.set_node_sampling_method_manual('transformation',method)
        else: 
            self.sampler.set_node_sampling_method_auto('transformation')
        last_sample = self.sampler.sample_node('transformation',nsamples=iterations,trace=trace) 
        # This is not necessary, but it triggers the cache of the resampled source image: 
        self._set_transformation(last_sample) 
        return last_sample 

    def resample_in_target_space(self,image): 
        # FIXME 
        #print "Resampling .."
        transformation = self._get_transformation() 
        return image

    def _get_resampled_source(self): 
        #FIXME: remove the next few lines
        if self.transformation.sum() != 0: 
            return self.target
        
        if self._resampled_source_need_update: 
            resampled_source = self.resample_in_target_space(self.source)
            self._resampled_source_cache = resampled_source
            self._resampled_source_need_update = False 
        else: 
            resampled_source = self._resampled_source_cache
        return resampled_source 

    def display_in_browser(self,axis=0,shrink=256,rotate=90,subsample_slices=4,scale_factors=None):
        self.display(axis,shrink,rotate,scale_factors,open_browser=True)
        
    def display(self,axis=0,shrink=256,rotate=90,subsample_slices=4,scale_factors=None,open_browser=False): 
        resampled = self.resampled_source
        D = MultipleVolumes([resampled,self.target], axis, shrink, rotate, subsample_slices, scale_factors, open_browser)
        return D.display() 

    def _repr_html_(self): 
        return self.display()._repr_html_()

    transformation   = property(_get_transformation, _set_transformation, None)
    resampled_source = property(_get_resampled_source, None, None)
Ejemplo n.º 10
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from ilang.Graphs import Dependence, ProbabilisticGraphicalModel
from ilang.Models import Poisson, Smoothness 
from ilang.Samplers import Sampler
from ilang.Tracers import RamTracer
from ilang.Display import MatplotlibDisplay
import numpy



# Define the model components 
observation = Poisson('SPECT')
prior_activity = Smoothness('Smoothing_Activity') 
prior_attenuation = Smoothness('Smoothing_Attenuation')  

# Build the graph 
dag = ProbabilisticGraphicalModel(['activity','attenuation','counts','smoothing-activity','smoothing-attenuation']) 
dag.set_nodes_given(['counts','smoothing-activity','smoothing-attenuation'], True)
dag.add_dependence(observation,{'lambda':'activity','alpha':'attenuation','z':'counts'})
dag.add_dependence(prior_activity,{'x':'activity','beta':'smoothing-activity'}) 
dag.add_dependence(prior_attenuation,{'x':'attenuation','beta':'smoothing-attenuation'}) 

# Initialize the nodes of the graph   
dag.set_node_value('activity',numpy.ones((10,10)))

# Instantiate the sampler, tracer and display 
sampler = Sampler(dag)
tracer = RamTracer(sampler)  
display = MatplotlibDisplay(tracer) 

# Sample 
sampler.sample(1000,trace=False) 
Ejemplo n.º 11
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class RigidTransformationSSD():
    def __init__(self, target, source):
        self.target = target
        self.source = source
        self._resampled_source_cache = None
        self._resampled_source_need_update = True
        self._contruct_ilang_model()
        self._set_transformation(numpy.zeros((1, 6)))

    def _contruct_ilang_model(self):
        self.ilang_model = ModelRigidSSD('RigidSSD')
        self.graph = ProbabilisticGraphicalModel(
            ['target', 'source', 'transformation'])
        self.graph.set_nodes_given(['target', 'source'], True)
        self.graph.set_node_value('source', self.source.get_data())
        self.graph.set_node_value('target', self.target.get_data())
        self.graph.set_node_value('transformation', numpy.zeros((1, 6)))
        self.graph.add_dependence(
            self.ilang_model, {
                'target': 'target',
                'source': 'source',
                'transformation': 'transformation'
            })
        self.sampler = Sampler(self.graph)

    def _set_transformation(self, transformation):
        self.graph.set_node_value('transformation', transformation)
        self._resampled_source_need_update = True

    def _get_transformation(self):
        return self.graph.get_node_value('transformation')

    def estimate_transformation(self,
                                method=None,
                                iterations=30000,
                                trace=True,
                                parameters=None,
                                display_progress=True):
        if method != None:
            self.sampler.set_node_sampling_method_manual(
                'transformation', method)
        else:
            self.sampler.set_node_sampling_method_auto('transformation')
        last_sample = self.sampler.sample_node('transformation',
                                               nsamples=iterations,
                                               trace=trace)
        # This is not necessary, but it triggers the cache of the resampled source image:
        self._set_transformation(last_sample)
        return last_sample

    def resample_in_target_space(self, image):
        # FIXME
        #print "Resampling .."
        transformation = self._get_transformation()
        return image

    def _get_resampled_source(self):
        #FIXME: remove the next few lines
        if self.transformation.sum() != 0:
            return self.target

        if self._resampled_source_need_update:
            resampled_source = self.resample_in_target_space(self.source)
            self._resampled_source_cache = resampled_source
            self._resampled_source_need_update = False
        else:
            resampled_source = self._resampled_source_cache
        return resampled_source

    def display_in_browser(self,
                           axis=0,
                           shrink=256,
                           rotate=90,
                           subsample_slices=4,
                           scale_factors=None):
        self.display(axis, shrink, rotate, scale_factors, open_browser=True)

    def display(self,
                axis=0,
                shrink=256,
                rotate=90,
                subsample_slices=4,
                scale_factors=None,
                open_browser=False):
        resampled = self.resampled_source
        D = MultipleVolumes([resampled, self.target], axis, shrink, rotate,
                            subsample_slices, scale_factors, open_browser)
        return D.display()

    def _repr_html_(self):
        return self.display()._repr_html_()

    transformation = property(_get_transformation, _set_transformation, None)
    resampled_source = property(_get_resampled_source, None, None)
Ejemplo n.º 12
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from ilang.Graphs import Dependence, ProbabilisticGraphicalModel
from ilang.Models import MultivariateGaussian 
from ilang.Samplers import Sampler
from ilang.Tracers import RamTracer
from ilang.Display import MatplotlibDisplay
import numpy




# Define the model 
ndim = 10
model = MultivariateGaussian('gaussian') 

# Build the graph 
dag = ProbabilisticGraphicalModel(['x','mu','cov']) 
dag.set_nodes_given(['mu','cov'], True) 
dag.add_dependence(model,{'x':'x','mu':'mu','cov':'cov'}) 

# Initialize the nodes of the graph
dag.set_node_value('x',numpy.ones((1,ndim))) 
dag.set_node_value('mu',numpy.zeros((1,ndim)))
dag.set_node_value('cov',numpy.eye(ndim)) 

# Initialise sampler, tracer, display 
sampler = Sampler(dag) 
tracer = RamTracer(sampler)   
display = MatplotlibDisplay(tracer) 

# Sample 
sampler.sample(1000,trace=False) 
Ejemplo n.º 13
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class Registration_N_Images:
    def __init__(self, images):
        self.__images = images
        self.__make_graph()

    def set_transformation(self, tr):
        pass

    def set_cost_function(self, cost):
        pass

    def register(self):
        pass

    def __make_graph(self):
        self.ilang_graph = ProbabilisticGraphicalModel()
        self.ilang_graph.add_node("template")
        for i in range(len(self.__images)):
            self.ilang_graph.add_node("im_%d" % i)
            self.ilang_graph.set_nodes_given(["im_%d" % i], True)
        for i in range(len(self.__images)):
            self.ilang_graph.add_nodes(["sigma_%d" % i, "T_%d" % i])
            self.ilang_graph.set_nodes_given(["sigma_%d" % i], True)
            model = SSD_ilang("SSD_%d" % i)
            self.ilang_graph.add_dependence(
                model,
                {"sigma": "sigma_%d" % i, "transformation": "T_%d" % i, "source": "im_%d" % i, "target": "template"},
            )
        self.ilang_sampler = Sampler(self.ilang_graph)

    def _repr_html_(self):
        return self.ilang_graph._repr_html_()

    def __repr__(self):
        return "Registration of N images. "
Ejemplo n.º 14
0
class Registration_Two_Images(object):
    def __init__(
        self, source=None, target=None, degrees_of_freedom=3, sigma=DEFAULT_SIGMA, initial_transformation=None
    ):
        self.set_source(source)
        self.set_target(target)
        self.set_sigma(sigma)
        self.__make_graph()
        if initial_transformation == None:
            self.set_transformation(numpy.zeros(degrees_of_freedom))
        else:
            self.set_transformation(initial_transformation)

    def __make_graph(self):
        self.ilang_model = SSD_ilang()
        # The following is an alternative use of ilang models: define the log_p and gradient functions here in order to have access to
        # the local variables.
        self.ilang_model.log_conditional_probability_transformation = self.__P
        self.ilang_model.log_conditional_probability_gradient_transformation = self.__G

        self.ilang_graph = ProbabilisticGraphicalModel(["source", "target", "transformation", "sigma"])
        self.ilang_graph.set_nodes_given(["sigma", "source", "target"], True)
        self.ilang_graph.add_dependence(
            self.ilang_model,
            {"source": "source", "target": "target", "sigma": "sigma", "transformation": "transformation"},
        )
        self.ilang_sampler = Sampler(self.ilang_graph)

    def __set_space(self):
        # make sure that the images are in the same space
        if self.source.space != self.target.space:
            raise "Source [%s] and Target [%s] must be in the same space" % (source.space, target.space)
        self.space = self.source.space

    def set_transformation(self, tr):
        self.__transformation = tr

    def __get_transformation(self):
        return self.__transformation

    def set_cost_function(self, cost):
        pass

    def __initialize_registration(self, optimization_method="QuasiNewton_L_BFGS_B", n_points=DEFAULT_N_POINTS):
        self.ilang_graph.set_node_value("source", self.source.data)
        self.ilang_graph.set_node_value("target", self.target.data)
        self.ilang_graph.set_node_value("sigma", self.sigma)

        if n_points == None:
            n_points = self.target.shape
        self.grid = self.target.get_world_grid(n_points)
        self.resampled_target = self.target.compute_resample_on_grid(self.grid)

        self.ilang_sampler.set_node_sampling_method_manual("transformation", optimization_method)

    def register(self, optimization_method="GradientAscent", iterations=DEFAULT_N_ITER, n_points=DEFAULT_N_POINTS):
        self.__initialize_registration(optimization_method, n_points)
        self.ilang_graph.set_node_value("transformation", self.transformation)
        self.ilang_sampler.sample(iterations)
        self.transformation = self.ilang_graph.get_node_value("transformation")

    def set_source(self, source):
        self.source = source
        if hasattr(self, "target"):
            self.__set_space()

    def set_target(self, target):
        self.target = target
        if hasattr(self, "source"):
            self.__set_space()

    def set_sigma(self, sigma):
        self.sigma = sigma

    def get_result(self):
        result = self.source.copy()
        result.transform(self.get_transformation_matrix())
        return result

    def get_transformation_matrix(self):
        # rot = self.__transformation[0:3]
        # tra = self.__transformation[3:6]
        tra = self.__transformation
        return Transform_Translation(tra, self.space, self.space)  # FIXME: rotation and translation

    def display(self):
        D = MultipleVolumesNiftyPy([self.source, self.target, self.get_result()])
        # D = MultipleVolumes([self.source, self.target])
        return D

    def __G(self, transformation):
        #        print "Transformation: ", transformation
        # rot = transformation[0:3]
        # tra = transformation[3:6]
        tra = transformation
        T = Transform_Translation(tra, self.space, self.space)  # FIXME: rotation and translation
        re_s = self.source.compute_resample_on_grid(self.grid, affine_grid_to_world=T)  # FIXME: memoize
        gr_s = self.source.compute_gradient_on_grid(self.grid, affine_grid_to_world=T)
        re_t = self.resampled_target
        G_tra0 = (re_t.data - re_t.data * gr_s[0]).sum()
        G_tra1 = (re_t.data - re_t.data * gr_s[1]).sum()
        G_tra2 = (re_t.data - re_t.data * gr_s[2]).sum()
        G_tra = [G_tra0, G_tra1, G_tra2]
        G = numpy.asarray([G_tra[0], G_tra[1], G_tra[2]]) / self.sigma
        #        print "gradient:       ", G
        #        print "log_likelihood: ", self.__P(transformation)
        return G

    def __P(self, transformation):
        # FIXME: memoize (now image is resampled to compute log_p and the gradient)
        # print transformation
        # rot = transformation[0:3]
        # tra = transformation[3:6]
        tra = transformation
        T = Transform_Translation(tra, self.space, self.space)  # FIXME: rotation and translation
        resampled_source = self.source.compute_resample_on_grid(self.grid, affine_grid_to_world=T)
        P = -numpy.linalg.norm(resampled_source.data - self.resampled_target.data) / self.sigma  # FIXME: verify
        #        print "log_likelihood: ", P
        return P

    def _repr_html_(self):
        # return self.ilang_graph._repr_html_()
        return self.display()._repr_html_()

    def __repr__(self):
        return "Registration of 2 images."

    transformation = property(__get_transformation, set_transformation)