Our TV Picture Quality Tests

Color Accuracy

The white balance dE determines how accurately a TV can display different shades of gray, which range from white to black. Inaccuracies with the white balance are most noticeable with large areas of white or gray colors, like if you're using it as a PC monitor or if you're watching sports like hockey and basketball. We measure the white balance from 5% gray (nearly black) to 100% gray (pure white) at increments of 5%, with window sizes covering 18% of the screen, and we calculate the average of the inaccuracy with all the shades.

In the above grayscale gradient, you can see a fairly dramatic example of how an imbalance affects a particular shade of gray. The 70% and 80% shades on the left both have a good deal more red than they should, and this throws off not only their appearance but also the way they interact with close shades.

Interpreting the results is fairly straightforward, as there's a chart on the left that shows the dE for each shade of white from 0 to 100%. The longer the bar, the more error there is. Most TVs will have the most error with shades closer to white because they require the most color (pure white is a combination of red, green, and blue), while error with darker shades is less common. The graph on the right represents which colors are the most inaccurate for each shade of white. As you can see below, the TCL 4 Series/S446 2021 has minimal white balance inaccuracy, while the TCL 5 Series/S546 2021 QLED is terrible. Most shades of white are inaccurate because it's displaying too much red, so the image has a red color tone.

White Balance dE: 0.87 (TCL 4 Series/S446 2021)

White balance dE: 8.99 (TCL 5 Series/546 2021 QLED)

Note that our dE measurement of the white balance represents an average of the dEs of 20 different shades of gray. A given shade may have better or worse dE than the others. You can see in the table below that most people won't start noticing the white balance error until the dE is greater than 5.

The color dE measurement expresses how accurately a TV can reproduce the following colors: Red, Blue, Green, Yellow, Magenta, and Cyan. Generally, if a TV can reproduce these six colors accurately, the overall color accuracy for the rest of the color tones will also be good, so this is relatively consequential.

To evaluate color dE, each color is displayed on a window that takes up 18% of the screen and displayed at points of 25%, 50%, 75%, 95%, and 100% saturation, with a 75% stimulus, and we also measure pure white. The different levels of saturation show how well the TV displays the color at different shades; a 100% saturated red is different from a 25% saturated red, which is closer to pure white.

Looking at the two results below, you can see what the LG NANO90 2021 looks like before and after calibration. Both the white balance and colors are inaccurate before calibration, and those issues are fixed in calibration, resulting in a more life-like image.

Pre-calibration Color dE: 6.29
White Balance dE: 7.19

Post-calibration Color dE: 1.67
White Balance dE: 0.43

Most people can't tell when a color is slightly inaccurate because the human eye can't perceive that difference, so color accuracy is only a concern when there are major inaccuracies. Of course, if you're a photo editor that wants to use the TV for content creation, you'll want the most accurate TV possible.

Gamma is an expression of the luminance of a particular shade or color, so having a good gamma means that the luminance of that shade is exactly right for the target look. In other words, if the gamma is off, the image either looks too bright or too dark. Unlike the white balance and color dE, a gamma that's a bit off is easier to notice. We measure the gamma using a series of gray levels from 0 to 100% gray, so it's measured at the same time as the white balance. We measure the gamma for each shade of gray, and we get a resulting graph for all the different shades.

The target gamma is 2.2 across all scenes, represented by the yellow line in the graphs below. The gray line is the TV's gamma; if it follows the yellow line, it has a perfect gamma. If it's above the yellow line, scenes are too dark, and if it's below it, scenes are too bright. The Hisense U7G on the left has a perfect overall gamma of 2.2, and even if some dark scenes are slightly too dark and others are a bit over-brightened, it's still great overall. However, the Samsung QN800A 8k QLED on the right is much worse, as all scenes are too bright, and it gets worse for brighter scenes.

Gamma: 2.20 (Hisense U7G)

Gamma: 1.89 (Samsung QN800A 8k QLED)

You should also note that our gamma target of 2.2 isn't the only correct gamma. TVs typically have several gamma options available, usually ranging from 1.8 to 2.6. Our target of 2.2 is about in the middle and is targeted for darker rooms. Apart from 2.2, a gamma of 2.4 is also appropriate for very dark rooms, and a gamma of 2.0 works pretty well for brighter ones. It’s best for most people to avoid the other options, as they will likely be too dark or light. Below you can see examples of this on the LG NANO90 2021, with the gamma setting of 2.4 resulting in a darker image than the gamma at 1.9.

Gamma setting: 2.4

Gamma setting: 1.9

Keep in mind that the final gamma result is an average of the gamma of each shade. Even if a TV has an overall gamma of 2.2, it doesn't mean that all scenes are displayed perfectly. Still, you'll want a TV with an average of close to 2.2, as even a result like 2.4 is noticeable to enthusiasts.

The color temperature of a TV has to do with color accuracy. A warm color tone means that the colors are shifted more towards red than blue, and a cool color tone has colors that are closer to blue. Like the other tests, this test is measured automatically using the CalMan software.

Below you can see the difference between a cold TV on the left and a warm TV on the right.

Color Temperature: 8520 K (Amazon Fire TV 4-Series)

Color Temperature: 6271 K (TCL 5 Series/S546 2021 QLED)

The target color temperature is 6500K. Anything above it is considered cold, while anything below is warm. However, you'll only start to see differences after a 400-500K difference.

For the pre-calibration testing, the picture settings we use apply to all the models in a brand because we want to compare how TVs perform, and we don't want to necessarily measure which picture mode is the most accurate. We aim for neutral picture settings, and every year we test the new models to see if the same settings are still the most accurate for a certain brand. In each review, we list which picture mode, color temperature setting, and gamma setting were used. Below you can see a table of the picture settings we used for each brand in 2021.

Our post-calibration evaluation is an overall score for the quality of a TV's picture quality after a full-color calibration has been done. This score will give you an idea of what to expect from your TV if you do plan on getting a calibration done. That said, most TVs end up having about equally accurate color once calibration is done, so these scores aren't quite so important.

We calibrate the TV using the 2 and 10 or 20-point white balance settings, depending on what's available. Some TVs don't have as many calibration settings, so it's harder to calibrate for the most accurate image possible. Other TVs can't be calibrated too aggressively as fixing one issue might introduce another, so in that case, we try to calibrate it the best as possible without causing other problems. Also, we avoid extreme adjustments whenever possible. Ideally, the closer each adjustment is to zero, the better. Very aggressive calibrations can result in color banding.

In the post-calibration tests, we once again measure the white balance dE, color dE, gamma, and color temperature. In the settings page for each review, you can see which settings were used for the full calibration. Because each panel performs slightly differently, we don't suggest using our calibration values for your unit.