Wednesday, December 1, 2010

How the Eye Works

My optometrist helped me simplify this technical subject to the point where I almost get it.  Here goes.

There are rods and cones in the retina of the eye.  Rods are light/dark receptors.  Cones are colour receptors.  The human eye is designed in such a way that the rods vastly outnumber the cones.  This means that the eye is most sensitive to light/dark contrast.  Colour is second in sensitivity.  This is not to say that an individual can't be in love with colour.  However, even their eye is designed to be most sensitive to light/dark.

The implication to this design is that a painting with high light/dark (or value) contrast will attract people most.  For example, a painting with a few interesting shapes with high light/dark contrast will attract a viewer's eye from across the room - where colour is not seen.  After being attracted from across the room the viewer moves to the painting where the colour strategy becomes visible.  So get the light/dark value design with a few interesting shapes established.  Squinting is of supreme value here. Then apply the colour.

The colour application to a value plan gives many artists trouble.  In monochromatic, most do not have too much trouble.  In colour, reds, greens etc. fool many people.  These are middle value and tend to be applied too dark.  A good value scale will help with this.  Another tool for those of you who are studious is shown below.  I use this regularly when I teach.

Practical Colour Wheel with Pigments

This is an approximation of the values or specific pigments.  I have a much more detailed version for anyone requesting it.

I digress.  The retina of the eye occupies quite a small area.  Perhaps like a postage stamp.  The lens of the eye focuses the light image on the retina.  To understand the implication of this pretend you are my student.  I ask you to stare me in the eye.  Then I ask you "which eye are you looking at?"  You will realize that you can only focus on one eye at a time.  Then I ask you keep looking at the chosen eye, and describe to me what else you see.  You see all the other background, but it is out of focus.  This is another way of saying that the edges are soft.  The eye is attracted to a hard edge.

So now you have two powerful tools to help you construct a painting in such a way as to attract the viewer from afar, then to guide the eye to where you want it to go.


  1. Wow! This is really helpful. Thanks!

  2. That's great Karla. It is quite a comparison to how the camera works.