title: Problems with plt.show(), no errors returned yet no image shows
body: <p>I'm executing below code</p>
  <pre><code>import numpy as np
  import cv2 as cv
  from matplotlib import pyplot as plt
  imgL = cv.imread('tsukuba_l.png', 0)
  imgR = cv.imread('tsukuba_r.png', 0)
  
  stereo = cv.StereoBM(1, 16, 15)
  disparity = stereo.compute(imgL, imgR)
  
  plt.imshow(disparity, 'gray')
  plt.show()
  </code></pre>
  <p>there are no errors being returned, yet no image is showing up, ive tried reinstalling matplotlib but that didn't help</p>