##  Copyright (c) 2020 The WebM project authors. All Rights Reserved.####  Use of this source code is governed by a BSD-style license##  that can be found in the LICENSE file in the root of the source##  tree. An additional intellectual property rights grant can be found##  in the file PATENTS.  All contributing project authors may##  be found in the AUTHORS file in the root of the source tree.## # coding: utf-8import numpy as npimport numpy.linalg as LAimport matplotlib.pyplot as pltfrom scipy.ndimage import filtersfrom PIL import Image, ImageDraw  def MSE(blk1, blk2):  return np.mean(      LA.norm(          np.array(blk1, dtype=np.int) - np.array(blk2, dtype=np.int), axis=2))  def drawMF(img, blk_sz, mf):  img_rgba = img.convert('RGBA')  mf_layer = Image.new(mode='RGBA', size=img_rgba.size, color=(0, 0, 0, 0))  draw = ImageDraw.Draw(mf_layer)  width = img_rgba.size[0]  height = img_rgba.size[1]  num_row = height // blk_sz  num_col = width // blk_sz  for i in xrange(num_row):    left = (0, i * blk_sz)    right = (width, i * blk_sz)    draw.line([left, right], fill=(0, 0, 255, 255))  for j in xrange(num_col):    up = (j * blk_sz, 0)    down = (j * blk_sz, height)    draw.line([up, down], fill=(0, 0, 255, 255))  for i in xrange(num_row):    for j in xrange(num_col):      center = (j * blk_sz + 0.5 * blk_sz, i * blk_sz + 0.5 * blk_sz)      """mf[i,j][0] is the row shift and mf[i,j][1] is the column shift In PIL coordinates, head[0] is x (column shift) and head[1] is y (row shift)."""      head = (center[0] + mf[i, j][1], center[1] + mf[i, j][0])      draw.line([center, head], fill=(255, 0, 0, 255))  return Image.alpha_composite(img_rgba, mf_layer)