- 70.0%Smoothing
- 30.0%Detail Preservation
A TV's ability to clean up low-quality content streams without losing fine details is incredibly important in the era of streaming video. Recent surveys have shown that the average American subscribes to four separate video streaming services, and more than 83% of Americans use streaming services to watch shows and movies. There's no doubt that these services are incredibly convenient - offering instant access to thousands of shows and movies, and native integration into smart platforms makes it incredibly quick to pick up where you left off.
They almost all have one major downside, though. They all rely on dynamic compression to save bandwidth, regardless of your internet speed, and this compression results in noticeable compression artifacts like macroblocking and posterization. Our low-quality content smoothing test evaluates how well a TV can process these streams to reduce these issues, while also evaluating how well it maintains fine details.
Test Methodology Coverage
We added these tests as part of our 1.10 test bench update, and before that, we had no equivalent test. The test hasn't changed at all since then, so the results and scores are comparable across any review. Learn how our test benches and scoring system work.
| 1.10+ | |
|---|---|
| Smoothing | ✅ |
| Detail Preservation | ✅ |
When It Matters
These tests matter primarily if you watch any streaming content or TV over cable or satellite. If you mainly watch physical media or only use your TV for gaming, then it doesn't really matter. Nearly all streaming services use heavy compression to save bandwidth. After all, with millions of viewers around the globe, bandwidth costs for giants like Netflix and Disney+ likely rival the GDP of some small countries. This compression can lead to a ton of noticeable picture quality issues, especially in dark scenes. One infamous example of this is Season 8, Episode 3 of the HBO series Game of Thrones, titled The Long Night. The entire episode is extremely dark, leading to significant compression artifacts, and when it aired, there were a lot of angry fans complaining about the poor picture quality.
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Above, you can see two examples taken from that very episode. On the left is a portion of the screen taken around the 4:30 mark of the episode, streaming through the Crave (the Canadian streaming service for all things HBO at the time this article was published) app, playing on an LG C3 with all processing disabled. On the right is the same scene, but this time playing from the 4k UHD Blu-ray played through a Panasonic UB820. As you can see, the 4k version of the episode looks significantly better. There's no distracting macro blocking in the scene at all, and fine details around the dragon's wing and the tip of the trebuchet are significantly sharper. There's also a lot more noise, but this is a combination of finer-grain in the source content and high-ISO noise from the camera.
Monitoring the TV's internet bandwidth while playing the scene through Crave showed a peak of about 16Mbps, including audio and additional overhead. The Blu-ray player's internal bandwidth monitor shows around 30Mbps for the video only from that scene. Compression allows streaming services to significantly reduce the bandwidth needed. Most 4k streaming services peak out at around 25-30Mbps, whereas 4k Blu-rays often reach up to 80-100Mbps in some scenes. If you're not subscribed to your streaming service's 4k package, you might even see more compression, as lower packages are often limited to even lower bandwidth.
Our Tests
The goal of these tests is to evaluate how well the TV can smooth out banding artifacts and posterization in low-quality content streams. We also want to make sure it isn't losing details in areas that don't need smoothing. We set the TV to its most accurate calibrated image mode, then adjust the image smoothing settings to their highest settings. We use a checkerboard pattern to adjust the backlight to 200 nits for consistency and display our test video on the TV. We use a camera and manually adjust the focus using an alignment grid to eliminate moiré. As this is a manual process, there may be minor differences in image focus across reviews, but the score is always based on the in-person experience, not the photos, so this doesn't affect our results.
With setup complete, we now play our test video on the TV from a PC, with the refresh rate set to 25Hz, with a 32-bit color depth, RGB color format, and a 10-bit color depth. The PC is also set to the TV's native resolution, as we don't want upscaling to alter the results. These settings are important to remove any PC processing from the equation. The test video has been processed at a low bitrate to simulate a low-bandwidth stream, so the macroblocking and posterization are baked in. With the video playing, we pause the video at frame 150 and take a photo. You can see an example of the output photo above. With the testing portion complete, we now evaluate the photo and assign a subjective score to each of the two categories below: smoothing and detail preservation.
Smoothing
This test looks at how well the TV smooths out compression artifacts like macro blocking and posterization in low-quality content. We evaluate the image subjectively, assigning a score of 1-10 based on how well the TV smooths out the image. The main focus is on the darker areas of the image, as that's where compression artifacts are most noticeable.
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Above, you can see two examples of this test (click on the image to view more details). The Hisense U6N on the left does almost nothing to reduce banding. It's basically displaying the test video as-is. The video on the right shows the LG C6, and you can see that there's barely any remaining macro blocking in the darker portions of the screen.
Detail Preservation
The details preservation portion of this test looks at the rest of the image. A TV with good processing needs to be able to smooth out compression details in low-bitrate streams without removing the fine details in the rest of the image. We look at the details in the face to check for any over-softening or loss of fine details, which can sometimes give the image a waxy look. Interestingly, many TVs that perform poorly on the smoothing test score very highly on this section. Since their processing is doing very little to clean up the rough parts of the image, it's not really doing anything to reduce fine details, either. Very few TVs perform poorly at this test, but if you care about image smoothing, it's important to get a TV that scores well in both tests.
Conclusion
Nearly all TVs offer smoothing options for low-quality content. Settings like Smooth Gradation are designed to reduce banding and macroblocking when watching low-quality streams, including on almost all streaming services like Netflix, Disney+, and Prime Video. This compression is always there, even when you pay for the highest streaming tier, so getting a TV that performs well on this test is important if you watch a lot of streaming content.