Every TV is made up of tiny pixels, and each pixel has smaller subpixels that help display an image. A TV's resolution is determined by the number of pixels it has. Most modern TVs have a 4k resolution, but in reality, they have an array of 3840x2160 pixels, and older TVs may have a 1920x1080 (Full HD) or even a 1280x720 (HD) resolution. The way the pixels behave defines which panel type the TV has. Each pixel on an OLED TV has four individual subpixels: white, red, green, and blue (WRGB), which are never all on at the same time. OLEDs are able to individually turn off pixels, resulting in an infinite contrast ratio that produces deep and inky blacks. On the other hand, most LCDs have three subpixels: blue, green, and red (BGR). The way the pixels are shaped and behave helps determine the panel type (IPS or VA), which results either in wide viewing angles or a high contrast ratio.
We take photos of the pixel structure to determine what type of panel the TV has.
In terms of the physical pixels, there's nothing we actually test and measure for. However, we test to see how well a TV displays images at different resolutions, which may be affected by the subpixel structure. For example, the LG UN7000 uses an IPS panel with an uncommon RGBW subpixel structure where there are four subpixel layouts in a row: RGB, GBW, BWR, and WRB, so only one of every four pixels has full color (RGB). This results in a less accurate image with native 4k content and causes some upscaling artifacts; however, some people might not notice it. The RGBW subpixel structure can also affect text clarity when using the TV as a PC monitor, but luckily, it doesn't have issues upscaling lower-resolution content such as from cable boxes or DVDs.
You likely won't notice pixels on your TV unless you're watching from right in front of the screen and the pixel density is low enough that you can distinguish each pixel - such as on a 75 inch 1080p TV, for example. Below are two TVs with an RGBW subpixel structure on an IPS panel and a BGR structure on a VA panel.
We take a pixel photo of each TV to determine the subpixel structure, which helps explain some of its tendencies and behavior. You can take a pixel photo of your TV at home with a DSLR camera. We use a Nikon D750 with an AF Micro-NIKKOR 60mm f2.8D lens and a Kenko Auto Extension Tube Set DF for Nikon with 12mm, 20mm, and 36mm extension tubes. We set the camera's F-Stop at 16, ISO at 800, and shutter speed at 1/15. We use a white image to take the photo on an LCD TV, and various colored images for OLEDs. We zoom in until we see the pixels.
LED TVs have a backlight that projects light through an array of liquid crystals. Depending on the stimulus on each pixel, only a certain light frequency can pass through. Colors are produced by combining the three subpixels and regulating the amount of light it lets through.
Lately, companies have introduced new technology in some high-end models to improve the viewing angles of VA panel TVs. This technology consists of a layer that's put in front of the screen and enhances viewing angles at the expense of contrast ratio. However, this layer also prevents us from taking a clear photo of the pixels, as you can see in the picture below.
OLED TVs use emissive technology and each pixel emits its own light at different intensities. Each pixel on an OLED TV consists of four such subpixels, and all four are never on at the same time. This is why we always take multiple photos of our OLED TVs, as you can see in the photos below.
OLED TVs can individually turn off each pixel, which results in an infinite contrast ratio and perfect black uniformity. However, one downfall to OLED TVs is permanent burn-in, which happens when pixels are constantly displaying the same color, such as if you would leave the news on all day. However, we don't expect this to be an issue if you watch varied content.
You can read more about the various panel technologies in this article.
You can't change the pixels, so there's no way to improve them. However, if you have an OLED TV and would like to apply some methods to avoid permanent burn-in, there are a few settings that can help mitigate the risks.
For OLED TVs you should enable the following features:
A TV's pixels define its resolution and affect how an image is displayed. They can result in a high contrast ratio, wide viewing angles, or perfect black uniformity, depending on which pixel structure your TV has. Each pixel has subpixels that help display the colors needed for an image, and at times may affect the way text is rendered. However, some people may not notice the difference between each panel type and pixel structure.