Function main

Examples/ImageRegistrationMethod2/ImageRegistrationMethod2.py:37–95

A SimpleITK example demonstrating image registration with histogram mutual information as a similarity measure.

(args)

def main(args):
    """ A SimpleITK example demonstrating image registration with histogram
        mutual information as a similarity measure. """
    if len(args) < 3:
        print(
            "Usage:",
            "ImageRegistrationMethod2",
            "<fixedImageFilter> <movingImageFile>  <outputTransformFile>",
        )
        sys.exit(1)

    fixed = sitk.ReadImage(args[1], sitk.sitkFloat32)
    fixed = sitk.Normalize(fixed)
    fixed = sitk.DiscreteGaussian(fixed, 2.0)

    moving = sitk.ReadImage(args[2], sitk.sitkFloat32)
    moving = sitk.Normalize(moving)
    moving = sitk.DiscreteGaussian(moving, 2.0)

    R = sitk.ImageRegistrationMethod()

    R.SetMetricAsJointHistogramMutualInformation()

    R.SetOptimizerAsGradientDescentLineSearch(
        learningRate=1.0,
        numberOfIterations=200,
        convergenceMinimumValue=1e-5,
        convergenceWindowSize=5,
    )

    R.SetInitialTransform(sitk.TranslationTransform(fixed.GetDimension()))

    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, args[3])

    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 // 2.0 + simg2 // 2.0)