If you are a student yourself, you might go through that essay paragraph by paragraph, and test yourself to see if you understand each part. When you look at the parts that are moveable, check on how the ‘same’ colors change when they get brighter or darker.

If you are responsible for the pictures in your cinema, check the lesson at Cinema Test Tools – A Look At Light 

There is so much to know about the way that light turns into an image that we ‘see’. Absolutely no one understands everything about it. New discoveries are made all the time. So, if you learn just a bit more, you are an expert compared to others. Good luck and enjoy the ride.