Why response time is important in tv




















Its disadvantages are that it reduces brightness and causes flickering. When the frequency of inserted black screens is increased it is more effective in reducing blur and afterimages, however the time in which the screen is black is increased, which means that the perceived brightness is lower. Also, the constant switching between the real frame and the black screen can easily make the screen appear to flicker.

There are products that suppress brightness reduction and flickering by increasing the LC panel's refresh rate to Hz and inserting black screens accordingly. Now that we have explained about response times and techniques to reduce blur, let's use the sample videos shown at the start of this article to do a detailed check on actual LCDs.

We are using three models, one for each type of LCD panel drive system. The specifications for video display performance are given in the chart below. Play the video of monochrome letters scrolling across a monochrome background and check the black-white-black response time. Please observe the outlines of the letters and symbols. When the black-white-black response time is slow, the contours of the lettering may be blurred, afterimages may be left of the outlines facing towards and away from the scrolling direction, the lettering may seem to leave thin streaks behind it, and false colors may be seen.

At first the video scrolls horizontally from right to left, then vertically from bottom to top, and then diagonally from top-left to bottom-right. The lettering is scrolled five times and then speeds up. At first it takes about 10 seconds to get from one edge of the screen to the other, then around 5 seconds and finally around 3 seconds.

You should expect that the contours of the lettering have more apparent afterimages and false colors the faster the scrolling goes. The content is the same as the previous monochrome video but the color of the lettering and the background changes twice during the course of the video.

The directions in which the lettering is scrolled and the method of checking is the same as in the monochrome video. These sample videos have been created to make it easy to find the faults of response times, so probably in most cases faults are even easier to find in standard video content. In fact, at the present there are no computer LCDs that can display the scrolled lettering perfectly, without any afterimages or flickering. We did find afterimages and flickering in all three of our test models when the speed increased, but there was no particularly noticeable breaking up of the lettering or false coloring of their contours, so it was at a level where it was perfectly possible to watch the video content.

Looking at each model separately, the VA type could set the intensity of the overdrive circuit, with a choice of three settings: "Off", "Normal" "High".

With the color sample video in particular, the effect of the overdrive circuit settings was very clear: when it was "Off" there was a lot of "streaking" but this was considerably alleviated when it was set to "Normal" and became even less when it was "High". The black-white-black response time of the panel itself is a rather slow 25 ms so the monochrome sample video was a little slow, but the middle gradation response time is accelerated to 7 ms by the overdrive circuit and perfectly satisfactory for switching colors much used in normal video content.

The black-white-black response time of the panel itself is 13 ms, fast for an IPS type, and the built-in overdrive circuit boosted the middle gradation response time to 7 ms, producing a very stable video display. The EVW TN type has the fastest black-white-black response time, at 5 ms, and although there was little blurring in the monochrome sample video, afterimages were conspicuous in the color sample video.

The middle gradation response time has not been revealed but, since it is not equipped with an overdrive circuit, there is the typical TN type characteristic that some tones are very much slower than the change between black and white. At first glance the TN type seems to have a faster response time but we would like you to remember that the middle gradations, much used in normal video content, are slowed easily blurred. Next let's check the brightness and contrast, which are related to the impact of the video display, and the tone and color balance, which are related to detailed color representation.

The optimum brightness and contrast values depend upon the video being displayed, the viewing distance and the user's preferences. However, the appearance is generally improved if a high brightness and high contrast are set.

We have prepared the sample videos below for our next check. The first sample video juxtaposes a gradient and a smooth gray scale gradation.

The screen does not change and we would like you to observe it carefully. We would like you to adjust the LCD's OCD menu as necessary while checking whether there is sufficient brightness and contrast.

In most cases there is no problem when the brightness is at maximum, but try turning the brightness down slightly if you are bothered by the black looking washed-out and grayish. The higher the contrast is adjusted the greater the difference in brightness between black and white, giving impact to the display. However, if it is too high blocked-up shadows and blown-out highlights are produced, and the gradations are destroyed. On the other hand, if the contrast is too low the image quality is flat and monotonous, and the boundaries between the gradations also become hard to see.

If you want a strong contrast, you should increase the contrast until you can just about see the boundaries while looking at the gradient gray scale. Incidentally, the smooth grayscale pattern can also be used to check the display quality for still images in particular the gradation. In the case of still images, you should look to see if there is banding unnatural stripes anywhere on the smooth grayscale, but usually video images do not require such a high level of gradation. There are some products that, in order to produce forceful images, actually correct the gamma curve to an S-shape in the video settings and prioritize contrast over tone.

The three models we are using for our checks displayed the typical EIZO insistence on beautiful gradation expression, and the gray scale was properly displayed on all three. The EVW has the lowest brightness but the darkness of the screen should not be noticeable unless it is in a very bright environment.

When it came to contrast, as expected the VA-type EVW was excellent; it was well-modulated and the black was nice and tight.

Compared to the other two models, the EVW's dark areas lacked blackness and seemed slightly washed-out, although this was at a level that would not be noticeable if it were not being compared to such high-grade products.

The next sample video juxtaposes a smooth gray scale and a smooth color gradation the screen does not change. As well as adjusting the brightness and contrast, let's try changing the pre-set image quality mode and color temperature and check how the coloration changes.

In particular, the coloration should have a very different appearance when the color temperature is raised or lowered. For your reference, the standard computer color temperature and the international standard for HD image color temperature are both 6,K, while the color temperature is 9,K for analog TV images and so on in Japan NTSC.

When the color temperature is low the colors on the screen have a reddish tinge, which becomes bluer as the color temperature rises.

It is better if it is adjusted to the optimum color temperature for the video image source, but if the product has image quality modes the color temperature is also switched automatically according to the mode, so perhaps we need not worry too much about that. It is very difficult for the average user to visually adjust the RGB color balance. It is probably very common for someone to think that they have adjusted the color balance for each RGB but then notice some strange colorations when they watch some actual video content.

There was good tone and color balance in all three of our test models. Their image quality modes all have "Fine Contrast" and there were no problems when this was set according to the video source, for example "Cinema" or "Movie". They do have a function that enables detailed gain adjustments for each RGB but our tests found that there were no problems at all if they were left in the default settings.

Recently there are some products equipped with a "dynamic contrast" function to boost the contrast of the video or game being displayed.

Although often the name it is given depends on the product, simply stated it is a function that makes real-time adjustments to the contrast and backlight according to the video scene and enhances contrast in the time axis of the entire video.

For example, even if the LCD's original contrast ratio is "" when dynamic contrast is enabled the contrast ratio is boosted as far as readings equivalent to severalfold or tens of times higher. However, we would like you to remember that the contrast ratio in the hardware specifications cannot be enhanced, and that in fact the contrast does not look as different as the gap in the figures might suggest.

The advantage of dynamic contrast is that it boosts the liveliness with which the video or game is displayed and strongly enhances the perceived image quality. The disadvantages are that gradation is occasionally destroyed in some particular video scenes, and in some cases the brightness and contrast changes cannot keep up with the actual changes in the video and an unnatural brightness results.

They are not as consistent as IPS, but they definitely top the bar in terms of image quality. However, since VA has a higher contrast ratio, this implies that the pixels take a longer time to go from black to white and vice versa. In effect, you can expect blurs when you play fast-paced movies and games. On average, its response time ranges from milliseconds.

If you prefer a higher quality display with fast response time, then IPS is a good fit for you. Just make sure that you are buying a newer model. You might also want to consider the VA, especially if response time is not a priority for you. Save my name, email, and website in this browser for the next time I comment. July 8, What is Monitor Response Time? Why is Monitor Response Time Important? Is response time even a big deal?

When should it be a priority? When can it be ignored? Lisa Hayden. You may also like. The x-axis represents the time. The blue line is the luminosity, so you can see how long it takes to get from the red to green lines; in this case, it overshoots a bit, so it actually goes brighter than it should. This helps determine the amount of motion blur trail behind and at the front of each object. If there's a fast-moving object on the screen, and pixels take a long time to change colors, they don't keep up with the moving objects, so there's often blur in front and behind the object.

You can see the difference below; in the left photo, there's a trail that follows the RTINGS logo, and in front, part of the logo is either cut off or not the proper color. The response time is a lot quicker for the photo on the right, so there's less motion blur. It's an important measurement because it shows how long it takes for most of the image to form, which affects the sharpness of the moving objects. Ghosting is a type of motion artifact, and there are two types of ghosting: black smearing and overshoot inverse ghosting.

Because it takes the pixels a long time to change, there's a black trail following the object, like someone smeared black paint across the screen. This effect can also be known as ghosting. Most modern TVs aren't plagued by this issue like they used to be, and it's more common to be seen in VA-type monitors. This is more common on monitors with overdrive settings than TVs, but it's still possible on TVs. Too much overshoot causes inverse ghosting, which means a part of the object remains on the screen temporarily after it's passed, making it look like a ghost.

Although we don't measure flicker as part of our response time tests, it still affects the appearance of motion and we also measure the flicker frequency separately. This is a common issue on TVs whose backlight flickers at Hz or Hz, which can cause image duplication with 60fps content. Below are examples of two TVs that flicker at different frequencies; you can also see black smearing with the Samsung TV.

This is blur within the video itself, and it's not caused by the TV. Cinematographers usually keep this kind of blur in mind and will account for it when planning shots for the movie or show. OLEDs can turn individual pixels on and off, so they have a near-instantaneous response time, resulting in minimal motion blur. However, OLEDs can also suffer from motion from persistence blur, known as MPRT, which is caused by pixels staying on the screen for too long because the response time is so quick.

Although the response time is much quicker on the LG, motion looks the same between the two TVs. Like with any test, it's not perfect. Our response time tests for TVs are fairly basic compared to those on monitors. We even measure the overshoot error with monitors, which we don't do with TVs. Also, only posting a photo of our logo isn't entirely representative of all motion across different content. Our logo contains bright and dark elements and aims to replicate different things you'd see on your screen.

A video would be better to see how motion looks; that's another limitation of our testing. However, even though the TV testing isn't as detailed, it still provides a good idea of how fast-moving objects look on the screen. Most elements of motion handling are static. If you have the option to do so, watching media with a higher frame rate will help you avoid blur. Some TVs may also have a couple of settings that can improve other elements of the motion blur, though you should be aware that they each have their downsides.

We list those settings below. A fast response time makes motion look smooth, but a slow response time can lead to motion blur, which can be annoying for sports fans and gamers. To get a good idea of how much blur TVs have, we test them for their pixel response and overshoot times.

Your best bet for getting a TV with little blur is to find a model with a quick response time. You can also help reduce the amount of blur you perceive by watching higher-frame-rate videos or by enabling motion interpolation or backlight flickering features.

Just remember that enabling these sorts of extra features can introduce other issues to the video. Get insider access. Best TVs. TV Recommendations. View all TV recommendations.



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