The Contrast Ratio Lie! Can I Trust Manufacturer Specifications?

Looking at televisions side-by-side, you can often see some that have deep blacks and others that have bright whites. This can have a profound effect on the perceived picture quality and viewing experience. The contrast ratio is a measure of the difference between these white and black parts in an image. A higher contrast ratio means that there is a larger diffence between the darkest blacks and the brightest whites. A contrast ratio of 500:1 would mean that the brightest point is 500 times brighter than the darkest point. This seems like an important aspect of a televisions performance, so how much emphasis should we place on manufacturer's specifications on the subject? In short, not much.

Since the contrast ratio is a difference, increasing the contrast ratio can be done by having darker blacks or whiter whites. Plasma televisions have traditionally been more capable of delivering deeper blacks, while LCDs have had much brighter displays of white (see TV type comparison). So the same contrast ratio may actually deliver different picture images. But the confusion does not stop there.

There are also a variety of testing methods to determine a contrast ratio - and no standards. One method may benefit DLPs, while another testing method may benefit LCDs. Manufacturers understand that the numbers they publish influence purchasing decisions and they want to show how their product is better. In doing this, however, a consumer can be misled. This is further illustrated by comparing static and dynamic contrast ratios. A static contrast ratio takes a snapshot of an image and compares the lightest and darkest point. The dynamic contrast ratio, however, looks at the brightest vs. darkest points over time. Although manufacturers may not explicitly state which ratio is being referenced, very high dynamic contrast ratios are easier to achieve than static ones. An outstanding static contrast ratio may be 1,500:1, while it is not unusual to see a dynamic contrast ratio over 10,000:1.

Static and dynamic contrast ratios may be illustrated by looking at three televisions. The manufacturer specifications for the Samsung 46" DLP HDTV HL-T4675S lists its contrast ratio at 2500:1. The LG 42" Flat-Panel Plasma HDTV 42PC5D, on the other hand, has a manufacturer specified contrast ratio of 15,000:1 . What a difference! In each case, the type of contrast ratio and testing method is not disclosed. In reality, both television technologies are capable of deep blacks and superior contrast ratios. Likely, the larger contrast ratio is a dynamic measure and the smaller contrast ratio is static. Our last example is the Philips Ambilight 2 42" 1080p Flat-Panel LCD HDTV 42PFL7432D. This manufacturer has opted to list both types of contrast ratios in its specifications, giving a 1,100:1 static and 8,000:1 dynamic contrast ratio. While it is refreshing to have a little more disclosure, testing methods are rarely discussed by anyone.

Additionally, there is another important thing to remember no matter which TV you buy. There are many controls on the television to adjust different aspects of the picture (i.e. brightness, color, contrast). Simply accepting the out-of-the-box settings on your new television is unlikely the best strategy. A proper calibration or picture adjustment can be more influential in obtaining a great picture than buying the television with best contrast ratio. After purchase, follow any manufacturer recommendations to optimize the picture quality. Keep in mind that individual situations and personal prefences play a role here, too. You may need to have an increased brightness level to compensate for a well-lit room, for example.

The confusion and ambiguity within contrast ratios makes it difficult to use this information effectively. I believe that is important to gather as much information you can about your television options, but some data you have to take with a grain of salt. In fact, other sources such as Gizmodo and Home Theater believe the contrast ratios provided by manufacturers are basically useless. I wouldn't be surprised to see manufacturers justify using a contrast ratio of 25,000:25 (which is really the same as 1,000:1). Oh, and be prepared for the next technology in HDTVs called OLED that boast a contrast ratio of 1,000,000:1. I think the blacks are so deep that they start to come out the back of the television.