title: Additive color on translucent dots
body: <p>I'm have a square icon, dimmed by a black mask.  There should be a number of dots on top of this mask, of various colors.  These dots are of addative color, so when on top of eachtother, they brighten.  In combination, enough of these these would turn the black mask multicolored or even white, revealing the image underneath.</p>
  
  <p>How could this be done? Client-side, with canvas or css3? Server-side, with ImageMagick or something else?</p>
  
  <p>Here's a link to additive color on canvas: <a href="http://contrapunctus.net/blog/2010/rgb-demo" rel="nofollow">http://contrapunctus.net/blog/2010/rgb-demo</a></p>