Here is how rear projection LCD TVs work. The idea is that different amounts of current cause different amounts of light to pass through the crystal and as you probably know, electricity changes the shape of the liquid crystals. But how do we add color? Color is added by having a mirror which splits the light into the three main colors - Red, Blue and Green (RGB). There are also DLP rear projection monitors which have a digital micro-mirror device (DMD) to produce the picture. Most of the DLP models have one DMD and a spinning, multicolored wheel that adds color.