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Results: Grayscale Tracking And Gamma Response

Asus PB287Q 28-Inch 4K Monitor Review: Ultra HD For $650
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The majority of monitors, especially newer models, display excellent grayscale tracking (even at stock settings). It’s important that the color of white be consistently neutral at all light levels from darkest to brightest. Grayscale performance impacts color accuracy with regard to the secondary colors: cyan, magenta, and yellow. Since computer monitors typically have no color or tint adjustment, accurate grayscale is key.

We’re showing you the results from both Game and Standard modes.

Most monitors have picture modes optimized for specific applications like Game or Text, so we want to show you what happens in those modes. When you select Game on Asus' PB287Q, the grayscale tracking runs a little cool but isn’t too bad overall. Unlike some other displays, you can adjust the RGB sliders if you want to improve the result. When we get to the gamma and color gamut measurements, you’ll get a better idea of what we’re trying to tell you.

When you select the User Color Temp preset, this is the level of performance you’ll see. There are no visible errors, but our i1Pro says the white point is a little on the cool side. Still, it's pretty much excellent for a measurement right out of the box.

By tweaking the RGB sliders a bit, we improved the tracking slightly. The greatest gains are at the bright end of the luminance scale. We also had to lower the Contrast control to clean up the 100-percent level. We’ve seen better grayscale charts. However, the PB287Q’s result raises no issues worth worrying about.

Back to the comparison group…

An un-calibrated error of 2.27 Delta E is well under the threshold of visibility. We would be perfectly happy using the PB287Q without adjustment. Of course, while it doesn’t need a calibration, we performed one anyway.

A result of 1.49 Delta E represents only a small improvement in grayscale performance. For some, the small reduction in contrast is too great of a price to pay for such a slight gain in accuracy. Remember that if you only adjust backlight intensity, you’ll see around 900 to 1 contrast, rather than the calibrated number of 764 to 1.

Gamma Response

Gamma is the measurement of luminance levels at every step in the brightness range from 0 to 100 percent. This is important because poor gamma can either crush detail at various points or wash it out, making the entire picture appear flat and dull. Correct gamma produces a more three-dimensional image, with a greater sense of depth and realism. Meanwhile, incorrect gamma can negatively affect image quality, even in monitors with high contrast ratios.

In the gamma charts below, the yellow line represents 2.2, which is the most widely used standard for television, film, and computer graphics production. The closer the white measurement trace comes to 2.2, the better.

We’re including three different traces to show the difference between Game and Standard mode, along with the effect of Asus' Smart View control.

In the charts above, you saw that the grayscale performance in Game mode wasn’t too bad. When it comes to measuring gamma, however, there's a clear price to be paid. The large dips at 10 and 90 percent mean detail in those ranges gets crushed. The impact on bright highlights is very obvious in real-world content.

Here is the gamma in Standard mode. It tracks very well and only runs slightly dark. The average value is 2.31, which is a tad higher than the preferred 2.2. The upside is that perceived contrast is a little better. Standard mode, without question, is the right choice for the best image quality.

Here’s what happens when you turn Smart View on:

I mentioned earlier that Smart View raises the black level and cuts overall contrast by 89 percent. The net effect is a flat and washed-out image with medium gray tones where black should be. It looks like Asus wants Smart View to help with shadow detail, but it would be more useful if the feature had four or five different levels rather than on/off.

Let's get back to the comparison group:

Although the gamma is a tad dark, it tracks extremely well. Gamma is nearly as important to image quality as contrast, and the PB287Q gives nothing away here.

We calculate gamma deviation by simply expressing the difference from 2.2 as a percentage.

Because of its 2.31 average value, the PB287Q doesn’t look great compared to the rest of the field. Don't let our result deter you though; it's a relatively minor error you can fix on your own by upping the Contrast control (so long as you don’t mind a little less accuracy in the brightest grayscale points). Whether you calibrate or not, we consider the gamma performance to be more than satisfactory.

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