Gray Uniformity of TVs: Dirty Screen Effect (DSE)

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What it is:

Evenness of colors onscreen (not just gray).

When it matters:

Solid colors. Sports, panning shots.

Score components:

  • 50%
    Std. Dev.
  • 50%
    DSE

Gray uniformity describes how well a TV is able to maintain a single, uniform color on the screen. Uniformity issues can look like darker patches around the screen, with corners and edges especially susceptible to looking darker than intended. It’s particularly an issue for sports, where darker patches on the screen can affect the look of playing surfaces.

To evaluate gray uniformity, we take a photograph of the screen while it is displaying a single, solid color. Using that picture, we calculate both the standard deviation of the color values of the pixels across the entire screen, and the number and severity of darker patches in the center of the screen (where they matter most).

Test results

Product Year Gray Uniformity Std. Dev. DSE Gray Uniformity Overall Our Reviews
LG EG9100 2015 55" Picture 1.201 % 0.113 % 8.9 8.5 See review
LG EG9600 2015 55" 65" Picture 0.658 % 0.128 % 8.7 8.8 See review
LG EC9300 2015 55" Picture 1.652 % 0.115 % 8.7 8.5 See review
LG EF9500 2015 55" 65" Picture 2.046 % 0.141 % 8.2 8.8 See review
LG E6 2016 55" 65" Picture 1.429 % 0.160 % 8.0 8.9 See review
Samsung JS8500 2015 48" 55" 65" Picture 2.454 % 0.147 % 8.0 8.1 See review
Sony X810C 2015 55" 65" Picture 2.069 % 0.164 % 7.7 7.7 See review
Samsung JS9000 2015 48" 55" 65" Picture 2.638 % 0.158 % 7.7 8.2 See review
Samsung KS9500 2016 55" 65" Picture 3.258 % 0.157 % 7.6 8.3 See review
Samsung KS9000 2016 55" 65" 75" Picture 3.194 % 0.159 % 7.6 8.3 See review
Samsung KS8000 2016 49" 55" 60" 65" Picture 3.536 % 0.165 % 7.4 8.2 See review
Sharp UH30U 2015 70" 80" Picture 2.542 % 0.185 % 7.2 7.2 See review
Samsung KU7000 2016 40" 43" 49" 55" 65" Picture 3.045 % 0.182 % 7.2 7.2 See review
Samsung J5500 2015 40" 48" 50" Picture 4.180 % 0.170 % 7.1 6.3 See review
TCL FS3800 2016 40" 50" Picture 4.562 % 0.172 % 7.0 6.9 See review
Sony X850D 2016 55" 65" 75" 85" Picture 3.981 % 0.180 % 7.0 7.6 See review
Samsung JU7100 2015 40" 50" 55" 60" 65" 75" 85" Picture 2.934 % 0.195 % 7.0 7.7 See review
Samsung JU6500 2015 40" 48" 50" 55" 60" 65" 75" Picture 2.793 % 0.197 % 7.0 7.2 See review
Samsung JU6400 2015 40" 48" 55" 60" 65" Picture 4.062 % 0.184 % 6.9 7.5 See review
Vizio D Series 1080p 2016 2016 32" 40" 43" 43" 48" 50" 55" 60" 65" 70" Picture 4.115 % 0.186 % 6.8 7.5 See review
Sony W800C 2015 50" 55" Picture 3.237 % 0.199 % 6.8 7.1 See review
Vizio P Series 2014 50" 55" 60" 65" 70" Picture 3.795 % 0.194 % 6.8 7.5 See review
Samsung JU7500 2015 40" 48" 50" 55" 65" 78" Picture 3.827 % 0.195 % 6.7 7.9 See review
Vizio M Series 2015 2015 43" 49" 50" 55" 60" 65" 70" 75" 80" Picture 3.743 % 0.198 % 6.7 7.4 See review
Sony X830C 2015 43" 49" Picture 3.911 % 0.196 % 6.7 7.1 See review
Vizio P Series 2016 2016 50" 55" 65" 75" Picture 4.527 % 0.188 % 6.7 8.2 See review
Samsung JS9500 2015 65" 78" 88" Picture 3.817 % 0.201 % 6.6 8.0 See review
LG LF6100 2015 50" 55" 60" Picture 3.476 % 0.206 % 6.6 6.6 See review
Sony R510C 2015 40" 48" Picture 4.714 % 0.191 % 6.6 6.8 See review
LG UF6800 2015 55" 65" Picture 3.862 % 0.204 % 6.6 6.6 See review
Sony X850C 2015 55" 65" 75" Picture 4.930 % 0.190 % 6.6 7.5 See review
Samsung JU6700 2015 40" 48" 55" 65" Picture 4.207 % 0.200 % 6.6 7.1 See review
Sony X930C 2015 65" Picture 4.351 % 0.199 % 6.5 8.0 See review
LG LF6000 2015 50" 55" Picture 4.176 % 0.204 % 6.5 6.2 See review
TCL US5800 2016 55" 65" Picture 3.132 % 0.220 % 6.5 6.9 See review
Samsung J5200 2015 32" 40" 43" 48" 50" Picture 4.593 % 0.200 % 6.5 6.4 See review
Vizio E Series 2015 2015 32" 40" 43" 48" 50" 55" 60" 65" 70" Picture 3.765 % 0.212 % 6.5 7.3 See review
Sony X900C 2015 55" 65" Picture 5.052 % 0.195 % 6.4 7.5 See review
Samsung J6300 2015 32" 50" 55" 60" 65" 75" Picture 3.635 % 0.215 % 6.4 7.3 See review
Vizio E Series 4k 2016 2016 43" 48" 50" 55" 60" 65" 70" Picture 4.409 % 0.207 % 6.4 6.3 See review
Samsung J5000 2015 32" 43" 48" 50" Picture 5.099 % 0.200 % 6.3 6.7 See review
Samsung JS7000 2015 50" 55" 60" Picture 5.261 % 0.200 % 6.3 7.4 See review
LG UH8500 2016 55" 60" 65" 75" Picture 4.790 % 0.209 % 6.3 7.8 See review
TCL FS3750 2016 40" 48" 55" Picture 3.039 % 0.234 % 6.2 7.1 See review
LG LF6300 2015 40" 43" 49" 55" 60" 65" Picture 3.920 % 0.225 % 6.2 6.6 See review
Samsung KU6300 2016 40" 43" 50" 55" 60" 65" 70" Picture 4.093 % 0.224 % 6.2 7.2 See review
Samsung J4000 2015 32" Picture 5.722 % 0.202 % 6.2 6.5 See review
Sony W600D 2016 32" Picture 6.621 % 0.190 % 6.1 6.5 See review
Samsung J6200 2015 40" 50" 55" 60" 65" Picture 3.983 % 0.230 % 6.1 7.3 See review
Sony X930D 2016 55" 65" Picture 6.366 % 0.198 % 6.1 7.9 See review
Sony W850C 2015 65" 75" Picture 4.237 % 0.228 % 6.0 6.8 See review
LG UF6400 2015 43" 49" Picture 6.324 % 0.201 % 6.0 6.7 See review
Sharp LE653U 2015 32" 40" 43" 48" 55" Picture 4.382 % 0.228 % 6.0 6.7 See review
LG UH7700 2016 55" 60" 65" Picture 4.765 % 0.228 % 5.9 7.4 See review
LG UF7700 2015 60" 65" 70" 79" Picture 4.853 % 0.227 % 5.9 6.8 See review
LG UF8500 2015 60" 65" Picture 3.256 % 0.249 % 5.9 6.9 See review
Sharp UB30U 2015 43" 50" 55" 65" Picture 4.213 % 0.241 % 5.8 6.8 See review
LG UF7600 2015 43" 49" 55" Picture 5.191 % 0.229 % 5.8 6.9 See review
Sony W650D 2016 40" 48" Picture 6.082 % 0.221 % 5.7 6.9 See review
Vizio D Series 4k 2016 2016 40" 50" 55" 58" 65" Picture 4.236 % 0.249 % 5.7 7.5 See review
LG LF5600 2015 32" 42" Picture 4.423 % 0.256 % 5.5 6.1 See review
LG LF5800 2015 42" Picture 4.503 % 0.266 % 5.3 6.6 See review
LG LF5500 2015 49" Picture 6.001 % 0.259 % 5.1 6.1 See review
LG UF9500 2015 65" Picture 7.717 % 0.249 % 4.8 7.2 See review

Show All 64 Reviews

When it matters

You’re most likely to notice gray uniformity issues while watching sports, since playing surfaces are usually large stretches of a single color. Dirty screen effect will also be most obvious when there is a panning shot during sports. Most non-sports media tends to be a bit more varied, so you shouldn’t have gray uniformity issues with anything else unless your TV has particularly poor uniformity.

Bad gray uniformity

LG UF9500

Good gray uniformity

Samsung JS8500

Because it's only usually really bad gray uniformity that is obvious, it’s not hugely important most of the time. If a particular TV has really bad gray uniformity, or if a person is very sensitive to this kind of problem, then the importance could increase some. If you get a TV with gray uniformity that you can’t live with, try making an exchange for a different unit.

Our tests

Picture

Rtings.com gray uniformity pattern Our test pattern

Our picture test captures the gray uniformity imperfections on a TV screen, and is meant to show you the quality of the uniformity as you would actually see it on a TV. Of our tests, we consider this the most useful for most people who are trying to get a sense of what kind of uniformity they can expect from a TV.

To evaluate the gray uniformity on TVs, we take a photograph of this 50% white (medium gray) image while it is being displayed on the screen. The image shows any imperfections in the reproduction.

Standard deviation

What it is:

Average squared difference of pixels when displaying a mid 50% gray.

When it matters:

Solid colors. Sports, panning shots.

Good value:

< 2.5%

Noticeable difference:

1%

Our standard deviation test measures the evenness of color reproduction across the screen, and tells us the average squared difference of the color values of pixels when a full-screen, 50% white (medium gray) image is displayed. A lower standard deviation means less difference is present, and that the picture is better.

This allows us to score the overall uniformity of the entire screen objectively. It’s useful for comparing TVs in absolute terms, but isn’t as useful as the picture test for comparing TVs for what you’ll actually experience.

LG LF6300 Gray uniformity Photo from 'Picture' test

LG LF6300 Gray uniformity Photo after processing

For this test, we take the photo of the screen from the picture test and process it with a low pass filter (Gaussian blur) to remove noise and artifacts (like moiré) created by the camera. We then calculate the standard deviation of the color values of the pixels using the following formula:

Dirty screen effect (DSE)

What it is:

High-frequency variance of uniformity. Dark spots on the screen.

When it matters:

Solid colors. Sports, panning shots.

Good value:

< 0.165%

Noticeable difference:

0.025%

Our dirty screen effect test also evaluates the amount of difference the color values of pixels have from the target color, but focuses only on the area around the middle of the screen, where variance tends to look like dirty patches.

This is a bit more important for sports than the standard deviation test is, because while the standard deviation test gives us an idea of how far the uniformity is from ideal in absolute terms, it doesn’t fully represent the issues people will notice with poor gray uniformity. Compare these two images. On the left is a TV with a higher standard deviation, but less DSE. On the right is a TV with lower standard deviation, but higher DSE. You can see the second has more dark patches around the middle, where they are likely to be problematic.

Samsung JU6700 Gray uniformity Std. Dev: 4.207 %

DSE: 0.200 %

Samsung JU6700

LG LF6300 Gray uniformity

Std. Dev: 3.920 %

DSE: 0.225 %

LG LF6300

To take this into account, we once again use the photo from our 'Picture' test, only this time we pass it through a high pass filter, so that low frequencies are removed from the image. The result is something like the image below and to the left (result multiplied by 50 for purposes of illustration). This isolates all the variations that cause the dirty screen effect, but does so for the entire screen.

In order to test just the middle of the screen, we multiply the values of that picture with those of the image in the below-middle, resulting in the below image to the right.

LG LF6300 High Pass 2 TV's 50% white image through high pass filter

DSE Weight Center-isolating image

LG LF6300 High Pass 2 Weighted Result

Finally, we calculate the root of the average of the squared values of the final image. The equation is similar to that of the standard deviation calculation above, but uses ‘0’ instead of the mean.

DSE Formula

Additional information

Gray uniformity variance by model & unit

Gray uniformity is unique to each individual panel. This means that no two TVs, even of the same model, will have matching uniformity. Generally, though, higher-end TVs will have better gray uniformity, as the manufacturers will have stricter standards for the panels being used.

Causes of gray uniformity issues

With LED TVs, gray uniformity issues are caused by a couple of factors. LCD panels are pretty sensitive to pressure, so extra pressure caused by misalignment of the TV's components, or by mishandling of the panel during manufacturing, could lead to defects appearing. Likewise, improper pressure can interfere with the light diffuser doing its job correctly, which can cause certain portions of the screen to be lit darker or lighter than intended.

With LED TVs, full-array and direct backlighting can also contribute to worse gray uniformity. It's often possible to see a faint grid on the screen, corresponding to the placement of the LEDs.

There are also just imperfections in the LCD panel itself, independent of pressure-related problems. It's this kind of uniformity problem, inherent to the panel, that OLED also has.

Getting the best results

Unfortunately, gray uniformity is entirely down to the panel you get. There are no steps available that will help you improve the gray uniformity.

Related settings & other notes

  • There are no settings to adjust.

Other notes

  • OLED TVs tend to do quite well with our test, which uses a 50% white (medium gray) image, but they have much worse uniformity with darker colors, which can be an issue.

Conclusion

Gray uniformity refers to how well a TV can display a single, solid color across the screen. It matters for any image containing a wide expanse of a single color, and in particular sports, where bad gray uniformity affects the appearance of playing surfaces. For each TV, we take a photo of the gray uniformity, calculate the standard deviation of the color values of the pixels, and then calculate the amount of dirty screen effect that is present.

Unfortunately, there are no steps that can be taken to improve gray uniformity – it’s entirely down to the panel you get. If you find yourself with uniformity that you cannot live with, you should exchange your TV for a different unit, or even a different model.

Source: www.rtings.com