How artificial intelligence can improve Smart TV

Samsung TVs: When Artificial Intelligence encourages cheating

In recent years, Samsung has advanced LCD technology in many ways. One step was the use of quantum dots to expand the color space. More importantly, the company has used sophisticated local dimming of the LED backlight - with boost mode - in its top LCD TVs in order to control and increase the luminance more finely.

In addition, the company has made a number of attempts to improve the viewing angle of VA type LCD panels - a major challenge. Of course, Samsung isn't the first company to do this. So why did Samsung seem to have succeeded in its last attempt while others failed? Well, if you look a little closer, you will see something very disturbing.

Here's the problem: Samsung's 8K TVs can't display 8K resolution, and the best 4K TVs from 2019 can't display 4K resolution. Unless …

Four subpixels each bundled

Rasmus Larsen

Rasmus Larsen is the editor of flatpanelshd.com, a website focused on display technology and the TV ecosystem from a consumer perspective. It is a source for news, detailed articles, technical reviews, and more.

Let's start from the beginning. In his article "Samsung TVs: When 8K is not 8K", Bob Raikes explained how Samsung uses subdomains and a wide-angle film to improve viewing angles - and how this affects energy efficiency. However, one of the secrets behind Samsung's ultra-wide viewing angle system actually has its roots in something else. The use of subdomains is just a door opener here.

Ever since Samsung introduced its "AI" processor for 8K TVs - a processor that has since made its way into 4K TVs - televisions have been using sub-pixel rendering technology. The aim is to improve the viewing angles through the use of subdomains with differently aligned liquid crystals. The company sometimes calls this "quad rendering" because it bundles four subpixels at a time and operates the "quad" as a group.

From here it gets a bit more technical and in order to fully understand the method, we would have to explain the differences between IPS and VA including the liquid crystal orientation and other factors. I'd rather use an example.

In the following example, the screen should reproduce a certain shade of green (G 96). If you look vertically at the screen, you notice how the panel controls its pixels in groups of four: The upper left subpixel lights up fully (G 255), the lower right is strongly dimmed, and the upper right and lower left are almost switched off. Only the combination of all four results in the desired shade of green (G 96) - and improves the viewing angle. With other panel types, each sub-pixel displays its own color gradation and all show the same color tone G 96.

In other words: the Samsung VA panel reduces the effective resolution in order to improve the viewing angles.

Not just under the microscope

Is this just a theoretical exercise on studying subdomains under the microscope? Not at all. Once you've seen the effect, it's very difficult to miss. In our example, we used a green still image to illustrate it. But as soon as real video content is transferred to the screen, the "quad rendering" is applied dynamically, depending on the composition of the image: In some scenes you cannot see anything, but in most scenes it is easy to see if you know what you are looking for got to.

In the image above, notice the darker areas above the woman's eyes or the darker areas near her hairline: you will notice lines and pixel patterns. This is an 8K TV that you shouldn't really be watching these things on. It's because you don't get 8K resolution with these TVs.

In other scenes, you may notice strange patterns in text or lines, or "noise" in gradients or complex patterns.

"Once you've seen the effect, it's very hard to miss."

In its largest 8K TVs, Samsung appears to be taking a different eight-domain approach, likely because it's easier to add extra pixel transistors to those larger TV screens.

In addition to a measurably lower coverage of the DCI-P3 color space in the latest Samsung televisions, the dynamic pixel rendering mechanism also has an effect on the color rendering, because the panel dims the colors or the luminance in some subpixels depending on the content. As a result, some scenes have a green cast that is mainly visible on gray tones.

Game mode without subpixel rendering

The fun part: you can easily check out how Samsung applies this dynamic pixel rendering mechanism. Reason: It is an active system that is operated by the integrated "AI" processor. When you switch to game mode, the system (and with it the rendering mechanism) will be disabled because it would likely increase the input delay too much.

When you turn on the game mode, you will immediately see the viewing angles narrow. Not a little, but clearly. The system was also designed to recognize test patterns such as a 1 × 1 chess board for benchmarks. It then turns off dynamic pixel rendering, which is ... questionable.

Significant limitation

The Consumer Technology Association (CTA) recently announced that an 8K television "must achieve at least 50 percent contrast modulation on a 1x1 grid pattern" in order to meet its 8K requirements. I don't expect Samsung's extensive range of 8K TVs to be able to meet this requirement. Unless, of course, the built-in test pattern recognition mechanism is activated.

Samsung's 8K "QLED" LCD TVs cannot display 8K resolution (except in game mode), and the 2019 high-end 4K TVs cannot display 4K resolution (except in game mode). It's a significant caveat that seems to be drowned out in all the noise around 8K TVs.

One might wonder why Samsung is willing to sacrifice resolution to improve viewing angles? I suspect the company's motivation has a lot to do with HDR and the drive to position their own LCD TVs as the brightest HDR TVs on the market. However, poor viewing angles destroy HDR for all viewers sitting outside the sweet spot. (uk)