What is the Difference Between an HDTV's Dynamic and Static Contrast Ratio?

When shopping for a high-definition television (HDTV), a significant consideration is the contrast ratio expressed as 10000:1, for example. An HDTV with a high ratio will produce truer blacks and show more detail in low-lit scenes. This should make it quite simple to spot a good contrast ratio, except there’s a catch. There are two types: dynamic and static. Understanding the difference will help simplify HDTV shopping.

The dynamic contrast is a measurement of the brightest white the HDTV can produce as compared to the blackest black — not necessarily at the same time or in the same scene. For example, some LCD HDTVs use technology that brightens the overall picture in well-lit scenes to achieve very bright whites, and dims the overall picture in low-lit scenes to achieve truer, darker blacks. A measurement of the whitest white in the brightly lit scene compared to the darkest dark in the low-lit scene results in the dynamic contrast ratio specification.

The static contrast measures dark and light in a static shot, or the highest contrast ratio achievable within the same scene at the same time. This is a smaller number but a truer measurement in terms of overall picture quality. It’s the measurement a shopper should take into account more so, perhaps, than the dynamic contrast, but because the dynamic ratio is a higher number, it’s often the number used on the specification card of the HDTV, especially if the static number is poor or average.

While the best judge of a good picture remains the viewer's own two eyes, specifications come in handy for comparing products that aren’t side by side (or when buying online). Many experts generally recommend a dynamic contrast ratio of at least 10,000:1. Some HDTVs today list ratios of 50,000:1 or higher. As stated previously, however, the static ratio is more important.

A good starting point for the static contrast ratio is a minimum of 1,000:1. Some HDTVs list specifications as high as 1,500:1, 2,500:1, or even 5,000:1. Remember that a high number may be referring to the dynamic specification, though time is bringing improvements to static specifications, so shoppers should be sure to check which type of ratio is being advertised. Plasma HDTVs, for example, tend to have higher contrast ratios overall than LCDs.

Knowing the difference between these two measurements takes the confusion out of seeing an HDTV with a contrast ratio of 1,800:1 (for example), and noting it looks better than the HDTV with 10,000:1 listed. In reality 1,800:1 is a relatively high static ratio, while 10,000:1 is an average dynamic ratio.

Whenever possible, shoppers should look at actual displays before buying. If purchasing online, they should try going to some local outlets first to see the TV in action. Specifications help, but the eyes are the better judge for what will be personally pleasing.