This project is about encrypting secret messages. To understand the science behind decoder glasses, it is all a matter of light reflection, transmission, and absorption. These lenses produce the images you see by color filtering the layered image that you're actually looking at. The lens filter out all the red on the paper, which makes the blue colored wordings appear. If you place your transparent red sheet on top of your white sheet full of scribbles, it will also appear red. Why is this? Because the red sheet filters the light reflected by the white sheet. Only the red light passes through. And so the white paper appears “red” to us if we look at it through our transparent plastic sheet
