Noise Reduction
"Hey," you might argue, "why do I want to turn off noise reduction? I don't want to see any noise on my TV!" That would seem to make sense, except it doesn't.
Noise—sometimes called "snow" due to the appearance of black and white dots in the picture—was a bigger issue with older analog TVs, and especially with lower-definition analog signals. And, yes, when TVs upconvert video signals from lesser-quality sources you may still see some noise.
But for the most part, you're getting much cleaner, higher-quality digital source content these days, whether its over-the-air digital broadcasts, high-def signals from cable and satellite TV services, streaming service signals, or pristine video from Blu-ray discs.
The problem with engaging noise reduction is that it comes at the expense of detail and fine texture—these tend to get smoothed over when the feature is active. The picture can get soft-looking. Turn off noise reduction and you'll have more picture detail and a more natural-looking image.
The most common cause of video noise is the TV itself. If you're watching a standard-definition (480i) signal, such as DVD or SD cable/satellite channels, the TV has to upconvert that to display it full-screen. This process has to create millions pixels every second out of thin air, so to speak. Most modern TVs are pretty good at it, but there are unwanted side effects. In an effort to make the image as detailed as possible, the TV might end up accentuating the noise more than the actual detail in the image. This is a delicate trade-off on the part of the TV manufacturers: lots of detail but some noise, or less detail but no noise. Some of the best scalers are able to have lots of detail and little noise. The worst, the opposite.
Adding noise reduction in these cases may create a "smoother" image, but it's also likely robbing you of some fine detail.
Another culprit in the noise department is the Sharpness control. This is always an "edge enhancement" control. It adds an artificial edge around sharp lines to give the appearance of detail, when in reality it's doing the opposite (masking fine detail). It can also accentuate small amounts of noise in the image. If your TV has lots of video noise, try turning down this control a lot. For that matter, this control should be close to 0 on all TVs. Try it. At first the image will appear softer, but as you get used to it, you'll start noticing a lot more fine details like hair, wrinkles, textures in clothes, and so on. In some cases, though, turning the Sharpness control fully off does actually soften the image (for reasons no sane person can figure out).
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