title: Change type of Mat object from CV_32F to CV_8U
body: <p>I tried to display an image of CV_32F type using imshow function but it showed a <strong>WHITE image</strong>. In the <a href="http://docs.opencv.org/modules/highgui/doc/user_interface.html">Documentation</a> its given that floating point images will be mapped to 0-255 and displayed but it just showed a white image.I tried to convert it to CV_8U using </p>
  
  <blockquote>
    <p>Mat A=Mat::ones(300,300,CV_32FC1)*1000;</p>
    
    <p>do some processing - assigning float values to pixels in A</p>
    
    <p>......</p>
    
    <p>Mat B;</p>
    
    <p>A.convertTo(B,CV_8U)</p>
  </blockquote>
  
  <p>When I imshow 'B' i get a black &amp; white image, there are <strong>no shades of gray</strong>. Are the float valued pixels in A properly mapped to 0-255 ? Am I doing anything wrong?</p>
  
  <p>Few values in A are 1000 as initialized and rest are some floating point numbers which are assigned during processing.</p>