The light box is a useful tool to any artist. If somebody wants to draw a copy of something, or draw a figure into their picture from another, that effort can be greatly facilitated by use of a light box. The light box is simple in design. It is essentially a drawing desk where the drawing surface is either transparent or translucent, and the desk contains a bright light.
Using the Light Box
By putting a picture (on paper of normal thickness) on top of the desk, placing another sheet of paper (standard thickness as well) on top of it and turning the light on, the image underneath is easily seen on the paper above it. That is used to trace from the picture beneath to the picture on top, by hand. This method can be used for tracing the whole picture, a single object, or even a single part of an object, such as an eye or accessory.
In order to understand how the light box works, the properties of light and color must be understood. If we look at a leaf, it appears to be green. It appears green because as light hits it, all colors of light except green are absorbed into it. The green light bounces off, where it reaches your eyes and you see green. If you were to enter a dark room, holding a perfectly red ball, and you were to shine only green or blue light (as with a blue or green LED) on it, it will appear to be black. That is because it is completely absorbing all the light, and there is no red light to reflect back to meet your eyes. If it does appear to have color, then the ball is not perfectly red.
If the paper being used is thin enough, light is able to escape through it. However, if there is something in, say, black ink, the light will all be absorbed as it tries to move through it. For red ink, all but red light will be absorbed as it moves through it, making the red show through the layers of paper. Simply put, the light box lets you see what's on one sheet of paper through another one.