title: Dotted style overlay effect
body: <p>I have recently stumbled uppon this website <a href="http://demo.grandpixels.com/?theme=linguini" rel="nofollow">GrandPixels</a>
  and found one interesting effect. In the slideshow section you can see that images are kind of dotted, by zooming in I discovered that these dots are not the parts of the images but sort of overlay, achieved with CSS, I assume. Could anyone explain how this effect is achieved, ideally with css?</p>