Sharpness processing is an important aspect of a TV's upscaling. It's an important factor in determining how well a lower-resolution signal is upscaled to match your TV's native resolution. This is especially important if you're watching low-resolution content from an external player that doesn't have its own upscaling feature, like a cable box or an older DVD player. Good upscaling accurately scales lower-resolution content to the higher-resolution pixel count of the screen, maintaining fine details and delivering a sharp, clear image with no noticeable defects. Poor upscaling and sharpness processing will do a bad job of translating this detail, rendering the image blurry or overly sharp.
Test Methodology Coverage
Our Upscaling: Sharpness Processing test was originally added as part of the 1.11 test bench update. Prior to that update, we had separate upscaling tests done at 480p, 720p, 1080p, and 4k. The criteria used to evaluate upscaling on those tests were different, so the new test results aren't comparable to older reviews. Learn more about how our test benches and scoring system work.
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| Upscaling: Sharpness Processing | ✅ |
When It Matters
Most TVs on the market now have a native 4k resolution. A lot of the content we watch, like Blu-rays, DVDs, and most cable TV stations, has a lower resolution, usually 1080p. You might also be limited to 1080p if you're not subscribed to the 4k package of your favorite streaming service. Whenever a TV displays content with a lower resolution, it has to scale the image to match your TV's native resolution; otherwise, it wouldn't fill the screen, and you'd see a lot of black space around the image. This process is called upscaling.
These results matter if you watch a lot of lower-resolution content, like the sources mentioned above. It's not important if you mainly watch 4k UHD Blu-rays or are using your TV for gaming with a recent console like the Xbox Series X, PS5, or Nintendo Switch 2.
Our Tests
This test is limited to looking at how well a TV can scale text and sharp edges in an image. Although this is only one aspect of a TV's upscaling capabilities, it's often one of the most noticeable, and unwanted edge enhancements and poor sharpness processing can be very noticeable.
To test sharpness processing, we use a custom 480p video with a non-square (anamorphic) pixel aspect ratio. Even though we're using a 480p signal, the results of this test are valid for any low-resolution or low-bitrate source, like DVDs or cable TV channels. As the quality of the signal increases, the sharpness processing of the TV is less important, though, as the TV doesn't have to work as hard to produce a nice image. Even going up to 1080p can make a huge difference, as most modern TVs do very little processing on 1080p signals like Blu-rays, so issues that are exposed with a 480p signal aren't as obvious. We evaluate how well the TV displays the test content and assign a subjective score based on the final image.
Upscaling: Sharpness Processing
The first step in our upscaling test is to determine the ideal sharpness setting for each TV. We use a sharpness test image from the Spears and Munsil HD Benchmark 2nd Edition Bonus DVD and adjust the sharpness setting on the TV to find the maximum setting that introduces the least amount of artifacts or errors in the image. This ensures that straight lines remain straight and text is easy to read. We start by setting the sharpness setting to its maximum, introducing artifacts like digital noise and white padding around lines. We then lower the sharpness setting until those issues are no longer noticeable at a comfortable viewing distance.
Once we've determined the optimal sharpness setting for the TV, our next step is to evaluate the sharpness processing of the TV with our test video clip. We connect the TV to a PC and set the computer to send a 720x480 resolution with the output color format set to YCbCr, with 4:2:0 chroma subsampling, as this is the color format used by most DVD and low-resolution sources. We use MPC-HC to play our upscaling video on the TV in a loop and take multiple pictures.
The score is subjectively assigned based on the sharpness of the image and the quality of the upscaling. There are a few different points of comparison in the test clip that make it easy to see the differences in a TV's upscaling. The roof shingles should be clearly visible with good upscaling, whereas low-quality upscaling causes the shingles to blend together. Next, there's some text throughout the scene, including the names of the boats. Again, with good upscaling, the names should be easy to read. Finally, there's an overlay that closely mimics how well a TV can upscale hardcoded subtitles. Since each line is progressively smaller, it's easy to see where a TV starts to struggle, so we can objectively score their performance. Most begin to struggle at around the third line, where the "T" starts to be difficult to read and the "I" and "N" combine.
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Sharpness processing is about balance; we want the TV to scale the image without adding too much sharpening, which can add a halo effect around objects. Too little sharpening, and the image will look soft, and fine details will be difficult to make out.
It’s important to note that because the quality of 480p is so low, even top performers on this test won't produce an amazing picture. You can see two examples of this above. The Sony BRAVIA 9 has fantastic upscaling; it's about as good as it gets, whereas the LG UA77 next to it is considerably worse. You can see that some detail is lost in the softer picture, but also that neither looks great. Fine details on the LG are hard to see, and text, especially the RTINGS text in the bottom-right of the image, isn't well defined, and edges appear soft.
How To Get The Best Results
Ideally, if you care about the image quality, you should choose high-resolution, high-quality sources, like UHD Blu-ray or even regular Blu-ray. If you have a large collection of movies or TV shows on DVD, though, make sure you get a TV that performs well on this test. Unfortunately, most TVs don't let you adjust the upscaling performance, but you can adjust some processing features, like sharpness.
When watching DVDs or other low-resolution content, if you find the picture looks too soft, try making a very small increase to sharpness. Do this until you get a little more definition, but stop before adding harsh lines or big halos to objects. When using low-quality media with a lot of noise, it can also be a good idea to enable noise removal features. Try these features out and leave them enabled if you like the effect, and disable them if you find the picture becomes too blurry or you notice a loss of fine details.
Related Tests
- Low-Quality Content Smoothing: Whereas sharpness and upscaling look at a TV's ability to scale a lower-resolution image and display it cleanly, smoothing looks at how well a TV can process that image to smooth out rough areas of the content and reduce banding and macro-blocking caused by a low-bitrate signal. Whereas upscaling is mainly important for low-resolution content, smoothing is mainly important for low-bitrate content. Although many people believe that streaming services are generally high-quality, they usually aren't. Even if you have the highest tier available on your streaming platform and it's still sending a 4k signal, almost all streaming services use compression algorithms to reduce bandwidth usage, since bandwidth is expensive. This results in noticeable compression artifacts, such as black blocks in near-black scenes.
- Supported Resolutions: It's important to know how well a TV can upscale lower-resolution signals, but if you're planning on connecting legacy devices to your TV, it's also important to know which formats are supported.
Conclusion
Upscaling is a feature TVs use to make lower resolutions fit their screen. Good upscaling preserves detail in an image, making the picture look properly crisp, not blurry or overly sharp. For that reason, you should make sure you get a model that's able to upscale lower resolution signals well, and that can process the sharpness of the image properly, with no artifacts from over-sharpening.
If you find a given resolution upscales blurrily on your TV, you can increase the sharpness a little to add the definition you're looking for. If you notice there's lots of random noise in the picture, you can enable noise reduction features to help get rid of that. With good resolution support (or the right adjustments), you'll be able to enjoy lower resolutions that look as crisp as they can.