title: Finding mean pixel intensity value of an image inside a contour
body: <p>I have found a particular contour in an image. I have created a mask with the entire image black except for the boundary points of the contour. The contour has been mapped perfectly. Click<a href="https://i.stack.imgur.com/ZIIqm.jpg" rel="nofollow noreferrer">here</a> for the picture of the contour created.</p>
  
  <p>Now I want to go to my original image and get the average pixel intensity value of all points inside this contour of the original image.
  When I use the cv.mean() function, do I get the average value of only the points specified by the mask, i.e. just the boundary points or all the points inside the mask?</p>