The importance of HD TV refresh rate is measured by the viewer. However, there are situations when a higher refresh rate can considerably benefit the user. While these higher refresh rates eliminate judder to some extent it is not totally gone from American TV. Some of the ways that a higher HD TV refresh rate may benefit the user include higher frame rates in computer, consoles, elimination or lessening of judder in movies, and less flicker.
The importance of HD TV refresh rate in computer applications.
With higher refresh rates you can expect to see more action faster and smoother then before. Higher frame rates means more action, and more blurring. Despite any motion blur shaders you may be using, the human eye will create the motion blur if the image moves fast enough.
The importance of HD TV refresh rate in movie applications.
The introduction of higher refresh rates means less judder in America, while PAL sets never really had a problem with judder to begin with. Pal TVs operate at a standard of 50hz or 50 refreshes per second, while NTSC operates at 60hz.
Movies are typically produced at 24 FPS, since the frame rate does not match the refresh rate, new frames must be introduced into the image to create a smooth 60hz. NTSC TVs suffer judder due to these additional frames and 24 not being a factor of 60. One method of preventing this judder would be to slow the frame rate to 20 FPS making it a direct 3:3 image ratio thus simulating smooth motion on 60hz. The reason PAL does not suffer this is that the 24FPS can easily be increased by 4% in terms of speed to make it a factor of 50hz or 50 frames per second. When a PAL movie is produced it is sped up by 4% then each frame is displayed exactly two times creating a seamless motion.
The way higher refresh rates effect this judder is by allowing for a different, image to copy ratio. 24 is a factor of 120 evenly, and therefor each frame can be displayed exactly 5 times to produce the effect of a fluid motion, with no shorter or longer frames.
The importance of HD TV refresh rate in televisions.
This may seem like an odd topic, but higher refresh rates directly effect how the TV relates to your eyes as well. This happens in the form of flicker. Though it may not be noticeable all the time, the liquid crystals inside your display are being open and shut to allow light or stop light from being displayed constantly. This creates the flicker many of us may notice on our screens.
While it’s not as noticeable on smaller screens, with larger screens and more powerful lights it can become more noticeable. This flicker can be the cause of epileptic seizures, and other adverse effects. By increasing the frequency of these closed periods and shortening the length of them you stop noticing the flicker, or at least don’t notice it as much.
While the human eye is said to only perceive as much as 30 frames per second, this does not include light and dark images intermixed. Lighter images will leave an after image, or a burn in on your eyes for a short period of time, so even though you may only perceive 30 frames, the light blurred your vision and made it appear to be smooth. While this effect holds true to most things a clear moving image is perceived as judder or missing frames.
This effect is due to the fact that the image is not moving fast enough to produce an after image to your eyes. With the proper motion effects even 10 FPS could conceivably be enough to produce a smooth image, or at least one that your brain would register as smooth.
The importance of HD TV refresh rate in TVs is not something that should be over looked. However, it is not the most important thing to consider. While refresh rate is important, if you are satisfied with your standard refresh rate, then you have no reason to run out and buy a new 120hz TV. If however you notice flicker and judder like some people, then you may want to see how these new 120hz TVs work to reduce those problems for you. It may be that what you notice, the TV isn’t at fault for. You are indeed a more informed consumer now, but how you choose to act on this knowledge is up to you.