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战斗力 鹅
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注册时间 2007-3-6
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https://www.rtings.com/images/te ... 6/local-dimming.mp4
As mentioned, our local dimming video represents how well the backlight can adjust when there's a moving bright image in a dark scene. We always show the maximum local dimming setting in the video, but we test for all the different local dimming settings and recommend which one performs best.
This test will show several things:
Black Crush: When there's a bright object, sometimes the local dimming over-darkens the entire scene, resulting in highlights being 'crushed'. It's best if the TV avoids this.
Blooming: Somewhat opposite of black brush, blooming causes bright objects to light up too many zones. This is noticeable when there's a glow around a bright object, like a street lamp or stars, and it could get distracting.
Number and Size of Dimming Zones: With local dimming, different groupings of LEDs – called zones – are dimmed or brightened at the same time. With many small zones, it's easy to control how each zone affects the image. Fewer zones cover bigger areas of the screen, which could lead to more blooming. By looking at how much space is brightened around the white dot at any given time, you should be able to get an idea of the size of the zones. Also, we use this video to count the dimming zones. However, we don't publish how many zones there are because it's an estimate and not an exact number.
Star Field: We use a Star Wars intro to evaluate how good the stars look. This is a way to see in real content whether there's blooming or black crush. On an ideal TV, each star is bright, and there's enough black space in between them.
Subtitles: Sometimes, dimming zones are so big that they can't differentiate between subtitles and the content. If that's the case, subtitles can be over-brightened, or there's blooming around them, which could be distracting. You can see an example of bad subtitles here.
Uniformity: Combined with our uniformity test, we see how uniform the screen is when there are bright highlights. We keep an eye out for any backlight bleed and blooming. Although our black uniformity test uses a test image, we use real content in this test and see if there are uniformity issues.
Zone Transition Visibility and Speed: When a bright object moves between dimming zones, we want to see if there's any obvious blooming or if multiple zones light up. We also want to see how fast the zonal transitions are; does the new zone light up too fast, and how long does the old zone stay on the screen? If the local dimming feature is bad at these, it's distracting and can even create a 'Golf Ball Effect' as seen on the TCL 8 Series 2019/Q825 QLED. |
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