title: Conversion of image type int16 to uint8
body: <p>I have an image with data type <code>int16</code>.
  So when I have to convert its range to 0-255, I got two ways to do that in Python.</p>
  
  <p>1) Use <code>numpy.uint8</code> function directly</p>
  
  <p>2) Use OpenCV <code>cv2.normalize</code> function with 0-255 range and then use <code>numpy.uint8</code>.</p>
  
  <p>In Matlab, we directly get the conversion using <code>uint8</code> function. 
  In </p>
  
  <p>Also in second case, I used <code>NORM_MINMAX</code> and the range of intensity values gets changed to <code>0-4</code>.</p>
  
  <p>What is the correct way to do the conversion?</p>