title: how to see if a rgb color is too light
body: <p>I have an aplication in which the customer chooses a color.
  I can't let this color be too light.
  Is there a way to see this, to prevent the customer from chosing a color that is too light?</p>
  
  <p>Thank you a lot!</p>
  
  <hr>
  
  <p>too light in the case is a color almost white....i have a web site with a white background and the user can choose a color through a jquery plugin. </p>
  
  <p>I want to allow the user to choose the color he wants, but cant be too light.</p>