The subject of light is like the subject of gravity. They both have secrets hidden away that scientists will be discovering for a long time.
But there is enough known about light that we can capture it with a camera lens, make changes of the captured images, and project it through a projector lens onto a screen. With these techniques, a director can put images into your mind in a way that creates the intended effect of laughter or sorry, fright or wonder.
Sound has a similar science and process, from a microphone to a speaker and that is the topic of the next piece.
We call the eye and brain and mind combination the human visual system.
This system allows us to see small amounts of light at amazing distances. We can see colors and changes while being bombarded with large amounts of light. The amount of light is called brightness. The difference between dark and light is called contrast.
The range of colors that the eyes can see, from pure white to the soft reds and greens and blues that are almost white, to dense greens and reds and blues that are almost black, and including black, is called a 'color space'.
The camera is not as good as the eyes, and can't capture all the subtle shades - but the shades that it can pick up are called the camera's gamut. In the same way, there is no projector that can create all the colors or deep blacks or bright white that is in nature, so we call what the projector can show the projector's gamut. There are different gamuts for your computer printer and computer screen.
Now that we know what brightness and contrast and color space and gamut is, what can we do with them? How can we use them in the cinema theater to know if what we see is a good picture or bad?
The best way would be to use some test equipment, but that really wouldn't work while we are watching a movie. We would miss some clever bit of dialog and irritate our neighbor. So let's skip that idea right now.
The next way is to learn how to look at a picture the same way that a professional cinematographer looks at a picture.
The easiest first step is to look at things that are dark. Usually, a dark suit or the shadows in a corner, should not be entirely black. They should have some shades of grey in them. You can see this in real life and you should see this on the movie screen. If there is no subtleness, we say that the projector is "crushing its blacks”.
It is a little bit harder to see the same effect in bright scenes. But once you get used to seeing 'inside the whites' you will notice that there is supposed to be many shades of white inside the whites. If there isn't, we say that the projector is "crushing the whites”.
There are a few reasons why don't we notice these things right away. The first is that the human visual system is amazingly adaptive. It allows us to presume that a scene that is showing a bright sky is as bright as a real sky. But the real bright sky might be 100 times brighter than the movie's bright sky. There are other technical reasons, but we are safe to put them into the category of the visual system adapting to the circumstances. Combined with the adaptation is the fact that we go to the movies to disconnect. The technical term is to "suspend disbelief”. We allow mice to talk, and rebellious robots to mingle around in mining ships off the Shoulder of Orion.
While we are suspending disbelief we don't notice that a sign that is a blue-green color in real life to be a light shade of green on the screen. In real life we might know that the sign is the wrong color. In the theater we let it be.
So how do we look at color in a way to discriminate good and bad from excellent? That is where we'll start Part Two of A Picture Made of Light.