NTSC Decoding Basics (Part 1)

— Field Assignment —

Try your own experiment sometime at home. Sit in a darkened room (preferably at night) where you have available a light that is adjustable on a dimmer control. Be sure to block the light source from your direct view. Now, slowly adjust the light source until you can just barely see any details in the room. Take note of the smaller items (those with high frequency detail) versus larger items having some areas of color. Carefully adjust the light until you can just see shapes…you are not likely seeing them in their true color. This is as close to black and white as the human eye gets in everyday life.

Continue to raise the light intensity until you see color in larger objects, but cannot see the color of smaller objects. You are now near the threshold sensitivity of your eyes for color. Continue to raise the intensity until you see the color of small objects in your view and note how bright the lamp must be in order to resolve their color. Certainly, there are many variables here including the type of light source you use, but this gives insight into the very nature of the human eye's sensitivity to brightness, detail, and color. These concepts are very important to the success of the NTSC color system.