Applying windowing to SimpleITK images.

window_level.py

import SimpleITK as sitk

def wl_to_range(wl):
  """Convert window, level, to range"""
  w, l = wl
  lower, upper = l-w/2, l+w/2
  return lower, upper

def remap_range(img, range):
  """Remap image intensities so that the range is transformed to [0,1]"""
  l, u = range
  img = (img-l)/(u-l)
  
  return img

def clamp(img, range=(0,1)):
  """Clamp intensities in img to range"""
  arr = sitk.GetArrayFromImage(img)
  arr[arr < range[0]] = range[0]
  arr[arr > range[1]] = range[1]
  
  out = sitk.GetImageFromArray(arr)
  out.CopyInformation(img)
  
  return out
 
 def apply_window_level(img, wl):
  """Apply a window to an image, such that intensities in the range are mapped [0,1] and anything outside is clamped"""
  range = wl_to_range(wl)
  img = remap_range(img, range)
  img = clamp(img, (0,1))
  return img