[Tom Line]

Tightening up your color constraints too much is a mistake. Ambient lighting definitely will affect your vision.

In addition, don't rely on just seeing one shape.

The most accurate vision systems will be those that combine the two approaches. They will look for the correctly color using fairly wide open constraints, look for shapes with fairly wide open constraints, then check the shapes position and verify their colors.

In other words, your vision system should check that what you see is around the right color, about the right shape, and has approximately the correct spacial relationship to the other target (vertical versus horizontal). This will result in a much higher % chance of you identifying the correct object and state.