title: Not losing the quality of pictures saved with cv2.imwrite()
body: <p>I am wondering seriously about the effects of <code>cv2.imwrite()</code> function of OpenCV.</p>
  
  <p>I noticed that when I read pictures with <code>cv2.imread()</code> and save them again with <code>cv2.imwrite()</code> function, their quality is not the same any more for the human eyes.</p>
  
  <p>I ask you how can I keep the quality of the image the same as the original after saving it using <code>cv2.imwrite()</code> function.</p>
  
  <p>I ask this question because I have really a serious issue in a larger program and when I checked the quality of the pictures saved by this function, I guesses that my problem comes certainly from this function.</p>
  
  <p>For example, I draw using the mouse movements small  red (Red=255) squares on picture . When I save the picture and count the number of pixels that have Red color equal to 255 I get very few of them only even if I draw a lot of them in pure red color. But when I check the image by my eyes, I notice the red pixels I drawed are not correctly saved in the correct red color I chosed (255).</p>
  
  <p>Any one does know how to resolve this problem ? I mean to save the pictures using OpenCV without degrading its quality.</p>