Stare at someone for as long as possible without blinking.

Now there are a couple of  Visualization Techniques you can try at this point ... 

1 : Close your eyes and allow their image or outline to come into focus. (try doing this in a room that is relatively dark, this will help to see their outline).

2 : Place someone infront of a white or black bachground. (Try not to visualize people standing infront of pattern or Prints).

Keep your eyes open.

Look in the areas just above their head and shoulders.

When you have looked as long as possible.

Close your eyes and try to see their image with your minds eye.

Let the picture of the light that shaped in thier image, come into your mind.

Don't expect to see colors right away. It will take time and then you will see them.

There is a Color Chart to go by to tell what the colors mean.