gistfile1.txt

def window_level(arr, window_center, window_width, lut_min=0, lut_max=255):

    # Basic sanity checking.
    if np.isreal(arr).sum() != arr.size: raise ValueError
    if lut_max != 255: raise ValueError
    if arr.dtype != np.float64: arr = arr.astype(np.float64)

    # Get window information.
    window_width = max(1, window_width)
    wc, ww = np.float64(window_center), np.float64(window_width)
    lut_range = np.float64(lut_max) - lut_min

    # Transform the image.
    minval = wc - 0.5 - (ww - 1.0) / 2.0
    maxval = wc - 0.5 + (ww - 1.0) / 2.0
    min_mask = (minval >= arr)
    to_scale = (arr > minval) & (arr < maxval)
    max_mask = (arr >= maxval)
    if min_mask.any(): arr[min_mask] = lut_min

    # Scale the image to the right proportions.
    if to_scale.any(): arr[to_scale] = \
      ((arr[to_scale] - (wc - 0.5)) /
      (ww - 1.0) + 0.5) * lut_range + lut_min
    if max_mask.any(): arr[max_mask] = lut_max

    arr = np.rint(arr).astype(np.uint8)

    return arr