title: Max color used in a RGB image
body: <p>I have some RGB images.</p>
  
  <p>What's the best way to know most color used in an image is Red or Yellow or White?
  The input images must have more than 50% red, yellow or white pixels and it's impossible to an image have two colors in same percentage.
  Other colors in image may be black or blue.</p>
  
  <p>Is there any function in <code>MATLAB</code> for this?</p>
  
  <p><strong>Note that i need a method with good performance for this!</strong></p>
  
  <p>Thanks in advance...</p>