ImageRegistrationMethod3/ImageRegistrationMethod3.py

#!/usr/bin/env python
# =========================================================================
#
#  Copyright NumFOCUS
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0.txt
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.
#
# =========================================================================
 
import SimpleITK as sitk
import sys
import os
 
 
def command_iteration(method):
    if (method.GetOptimizerIteration() == 0):
        print("Estimated Scales: ", method.GetOptimizerScales())
    print(f"{method.GetOptimizerIteration():3} = {method.GetMetricValue():7.5f} : {method.GetOptimizerPosition()}")
 
 
if len(sys.argv) < 4:
    print("Usage:", sys.argv[0],
          "<fixedImageFilter> <movingImageFile>  <outputTransformFile>")
    sys.exit(1)
 
pixelType = sitk.sitkFloat32
 
fixed = sitk.ReadImage(sys.argv[1], sitk.sitkFloat32)
 
moving = sitk.ReadImage(sys.argv[2], sitk.sitkFloat32)
 
R = sitk.ImageRegistrationMethod()
 
R.SetMetricAsCorrelation()
 
R.SetOptimizerAsRegularStepGradientDescent(learningRate=2.0,
                                           minStep=1e-4,
                                           numberOfIterations=500,
                                           gradientMagnitudeTolerance=1e-8)
R.SetOptimizerScalesFromIndexShift()
 
tx = sitk.CenteredTransformInitializer(fixed, moving,
                                       sitk.Similarity2DTransform())
R.SetInitialTransform(tx)
 
R.SetInterpolator(sitk.sitkLinear)
 
R.AddCommand(sitk.sitkIterationEvent, lambda: command_iteration(R))
 
outTx = R.Execute(fixed, moving)
 
print("-------")
print(outTx)
print(f"Optimizer stop condition: {R.GetOptimizerStopConditionDescription()}")
print(f" Iteration: {R.GetOptimizerIteration()}")
print(f" Metric value: {R.GetMetricValue()}")
 
sitk.WriteTransform(outTx, sys.argv[3])
 
if ("SITK_NOSHOW" not in os.environ):
    resampler = sitk.ResampleImageFilter()
    resampler.SetReferenceImage(fixed)
    resampler.SetInterpolator(sitk.sitkLinear)
    resampler.SetDefaultPixelValue(1)
    resampler.SetTransform(outTx)
 
    out = resampler.Execute(moving)
 
    simg1 = sitk.Cast(sitk.RescaleIntensity(fixed), sitk.sitkUInt8)
    simg2 = sitk.Cast(sitk.RescaleIntensity(out), sitk.sitkUInt8)
    cimg = sitk.Compose(simg1, simg2, simg1 // 2. + simg2 // 2.)
    sitk.Show(cimg, "ImageRegistration2 Composition")