title: Reduce the contrast and brightness of a background layer
body: <p>I have a menu screen, with an animated background layer. This background is calculated runtime, hence it is not a simple sequence of images, and it uses graphic elements that are used inside the application itself.</p>
  
  <p>As soon as these graphics elements are studied to be very colourful and visible, the background animation sometimes makes the menu that is on the foreground a little confused.</p>
  
  <p>So, I have to reduce the contrast of the background animation.
  What is the best practice to reduce the background contrast/brightness without changing the graphic elements?  (or maybe blur the background layer)</p>
  
  <p>And more, would it be possible to reduce the contrast/brightness ONLY on a portion of the screen, the one below and around the menu buttons, and leave the rest of the screen as it is?</p>
  
  <p>Thank you very much.</p>