print("N4 bias correction runs.")
 inputImage =sitk.ReadImage("C/Users/LENOVO/Desktop/Brats18_2013_1_1_t1.nii")
 maskImage = sitk.OtsuThreshold(inputImage,0,1,200)
 sitk.WriteImage(maskImage,"C/Users/LENOVO/Desktop/Brats18_2013_1_1_t1_Mask.nii")
 inputImage = sitk.Cast(inputImage,sitk.sitkFloat32)

 corrector = sitk.N4BiasFieldCorrectionImageFilter();

 output = corrector.Execute(inputImage,maskImage)
 sitk.WriteImage(output,"C/Users/LENOVO/Desktop/Brats18_2013_1_1_t1_Mask.nii")
 print("Finished N4 Bias Field Correction.....")