code: def oneImageNLF(img, img2=None, signal=None):
      '''
      Estimate the NLF from one or two images of the same kind
      '''
      x, y, weights, signal = calcNLF(img, img2, signal)
      _, fn, _ = _evaluate(x, y, weights)
      return fn, signaf oneImageNLF(img, img2=None, signal=None):
      '''
      Estimate the NLF from one or two images of the same kind
      '''
      x, y, weights, signal = calcNLF(img, img2, signal)
      _, fn, _ = _evaluate(x, y, weights)
      return fn, signal
docs: Estimate the NLF from one or two images of the same kind