is the difference between the dark part of the picture and the light area of the picture. It is calculated by dividing the peak white level by the light level at the dark park of the picture. Measurements are taken by displaying a 100% Window pattern and measuring the peak white and an area of black near the white rectangle. The contrast ratio of a picture can be enhanced much faster by obtaining a good black level than by increasing the white. If we could actually get black to go to zero the contrast ratio would go to infinity. You would have to go a blinding way in peak light output to otherwise reach anywhere near that number. The contrast ratio of a good black matrix TV set in reasonable ambient light conditions is about 50:1 Get rid of ambient light hitting the set altogether and the number is more in the order of 100:1. The contrast of a direct view TV set appears to be pretty good because of its ability to reject ambient light. Broadcast grade monitors, which do not have the black matrix "feature", are often hard pressed to reach contrast ratio numbers much higher than 100:1. On the other side of this coin, the average viewer at home doesn't see numbers any higher than 50:1, often being as low as 10 or 20:1 depending on how well black level is set and held by the TV set. It is even more difficult to get a good contrast ratio out of a two piece projection system. Lower peak white capability and less ability to reject ambient light can often lead to a picture that doesn't look as high in contrast as a good TV set.