Sharpness vs. Resolution
The common perception of sharpness (as used in video applications) is that it’s directly related to resolution and that sharpness increases the resolution of an image. However, that isn’t the case. The resolution refers to a fixed number of pixels (720p, 1080p, 4K, and 8K). The resolution of a source connected to a TV may be lower, but the TV (or projector) upscales the image so that the image displays using the number of allocated pixels on the TV screen. On the other hand, sharpness is a control that increases edge contrast so that objects become more distinct. The image resolution remains the same. While the sharpness setting makes the image appear to have more detail, it actually doesn’t.
Benefits of Using the Sharpness Control
These are a few ways that sharpness makes your TV viewing better:
If an image appears soft, use the sharpness control in small steps to make the object edges more distinct.With lower resolution images that have been upscaled, apply a small amount of sharpness.Sharpening the edges of the image may make objects look more distinct on a higher resolution TV.
The image on the left shows a normal sharpness setting. The image on the right has the sharpness setting increased slightly.
Pitfalls of Using the Sharpness Control
Image sharpness may not produce the desired effect. For example:
If the sharpness is pushed too far, halos and rough edges may appear around objects. If the picture source is noisy (it has film grain, source noise in the analog video, or TV broadcast noise), those effects become worse as the edges of the grain and noise are emphasized. When adding too much sharpness, objects appear to have coarse edges, giving the overall image a harsh look. The harshness affects other elements of the image, such as contrast, brightness, and color. This results in an overly pasty look on faces. Also, the texture of background objects, although looking 3D-ish, becomes more distracting. You may notice previously hidden small macro blocking or pixelation issues.
Other Setting Options Similar to the Sharpness Control
If images from specific sources look too soft, even on a 1080p or 4K TV or video projector image, use other setting options that provide more precision than the sharpness control, such as Detail (also called Edge) Enhancement and Noise Reduction (aka Digital Noise Reduction or DNR). These controls don’t change the resolution of the image. The resolution is determined by the source in combination with the number of pixels on the TV screen. When carefully implemented in small steps, detail or edge enhancement can fine-tune soft edges. Also, using small steps in the noise reduction setting can reduce halo effects or added noise, such as film or broadcast grain, and some of the harsh effects that might be brought out by the detail or edge enhancement setting. You may still run into a situation where the image displayed takes on a pasty look that may not be better than when you tried the basic sharpness setting. You may also find that a source may have edge enhancement already applied (common with some DVDs and Blu-ray discs). Using the TV’s sharpness, detail (or edge enhancement), or noise reduction in these cases may make things worse. Here’s what these other picture controls do:
Brightness: Makes dark areas brighter or darker.Contrast: Makes bright areas brighter or darker.Color: Increases or decreases the saturation (intensity) of all colors in the image together.Tint (Hue): Adjusts the amount of green and magenta in the image (used primarily to dial in better skin tones).
The Bottom Line: Use Caution When Using the Sharpness Control
TVs and video projectors provide several setting options to maximize picture quality but use caution when using the sharpness control.
The sharpness control gives the false impression that it will increase or improve the resolution of the TV’s image. However, it doesn’t increase resolution and can add undesirable effects that make the image look worse if applied incorrectly.Check the TV or projector’s default settings. Leave the default setting for sharpness alone or limit changes to one or two steps up or down.If you want to experiment with the sharpness, detail (edge enhancement), or noise reduction settings, take note of the default position so you can return to that point if you decide your changes don’t look good.You may find a specific source needs a slight sharpness adjustment, but others don’t.On many TVs, you can apply different picture setting preferences, including sharpness, to each input. So, you can change the sharpness setting where it may be needed on one input, and the other sources connected to other inputs are fine. This means you don’t have to make repeated changes for all your sources.
