Why doesn't HDR also address black levels

ASUS PA32UC-K in the test - 4K with HDR enthusiastic
3/8

Brightness, black level and contrast

The measurements are carried out after a calibration to D65 as the white point. If possible, all dynamic controls are deactivated. Due to the necessary adjustments, the results are lower than when the test series was carried out with the native white point.

The measurement window is not surrounded by a black border. The values ​​can therefore be compared with the ANSI contrast and reflect real-world situations much better than measurements of flat white and black images.

We achieved a maximum of around 430 cd / m² with the native white point. The manufacturer's information on the maximum brightness is 400 cd / m² in typical operation. However, the ASUS PA32UC should also be able to achieve a maximum brightness of 1000 cd / m² - presumably only in HDR mode. The brightness can be reduced to a minimum of 49 cd / m².

After the software calibration, the values ​​drop only slightly: the maximum brightness is 422 cd / m² and the minimum brightness is 48 cd / m². The latter is relatively high, but working in complete darkness should still be possible without any problems.

The manufacturer specifies the native contrast ratio of the IPS panel as 1000: 1. According to our measurements, it is on average a very good 1005: 1 after calibration.

ASUS specifies the dynamic contrast ratio as 100 million: 1. We normally do not pay any further attention to such information. However, the PA32UC has a 384 zone matrix that can be dimmed locally. We come back to the topic in the chapters “Subjective Assessment / Additional Features” and “DVD and Video”. At this point, however, you can say in advance that the test candidate is actually able - and with real added value - to achieve much higher contrast ratios.

The ASUS PA32UC also has an option in the advanced picture settings to improve uniformity. The uniformity compensation is deactivated at the factory, which makes little sense for photographers and designers with a ProArt device. Usually, better homogeneity is not free, but has to be bought with lower values ​​for contrast and maximum brightness. This is also the case with the ASUS PA32UC.

As can be seen in the graphical comparison, the maximum brightness drops to - still very impressive - 318 cd / m², and the contrast ratio is just a good 744: 1.

Image homogeneity

We examine the image homogeneity using four test images (white, neutral tones with 75%, 50%, 25% brightness), which we measure at 15 points. This results in the averaged brightness deviation in% and the also averaged Delta C (i.e. the chroma difference) in relation to the respective centrally measured value. The perception threshold for differences in brightness is around 10%.

Without uniformity compensation, the brightness distribution is only satisfactory with an average value of 5.36%. The color homogeneity is also only satisfactory both on average (1.91%) and in the maximum deviation (3.97%).

With the uniformity compensation activated, on the other hand, the brightness distribution is even very good at the maximum value and at least good on average. The color homogeneity improves in every respect from “satisfactory” to “very good”. We measure the maximum deviation here in the lower left corner with a Delta C of only 1.52.

Coating

The surface coating of the panel has a major influence on the visual assessment of image sharpness, contrast and sensitivity to external light. We examine the coating with a microscope and show the surface of the panel (foremost film) in extreme magnification.

Microscopic view of the subpixels, with a focus on the screen surface: the ASUS has a slightly dull-matt surface with microscopically visible depressions for diffusion.

Point of view

The factory specification for the maximum viewing angle is 178 degrees horizontally and vertically. These are the typical values ​​for modern IPS and VA panels. The photo shows the screen of the ASUS PA32UC at horizontal viewing angles of +/- 60 degrees and vertical angles of +45 and -30 degrees.

ASUS has obviously installed a high-quality IPS panel. At more extreme viewing angles, it is primarily the brightness and contrast that are reduced. The color temperature also seems to be a bit warmer, especially in the vertical. It's not unusual. Overall, the colors remain very stable and consistent with each other, even from extreme viewing angles. In addition, the ASUS PA32UC retains the drawing in very light and dark areas of the image above average.

All in all a very good result. The suitability for EBV is unrestricted despite the display size.

interpolation

The focus control also works on the digital inputs and is factory set to level 50. Even the standard Windows 10 background image looks visibly grumpy. On closer inspection, sharpening artifacts become visible.

This is undoubtedly counterproductive for the EBV. We therefore recommend reducing the controller by at least half or, even better, switching it off completely. Thanks to the 4K resolution, you can certainly not complain about the lack of sharpness.

As expected, the sharpness in the native resolution is very good. At 1280 x 720 you can see that the necessary pixel enlargement is mainly caused by additionally inserted gray pixels. This leads to somewhat bolder contours with a slight impression of blurring. Color fringes do not occur.

However, the ASUS PA32UC does not leave a particularly good impression with deviating page formats - also because the option to adjust the aspect ratio can be found hidden under "Advanced image settings - controls". The options “full screen”, “4: 3”, “1: 1” and “overscan” (HDMI only) are offered here. Justified scaling is generally missing. But even when testing a 4: 3 resolution (1600 x 1200), the "4: 3" option remained grayed out and only a distorted display (or a tiny 1: 1 display) was possible.

However, since the primary target group will always operate the device in the native resolution anyway, we do not weight the issue too much.

With the interpolation of the usual video resolutions in 16: 9 format - especially the Blu-ray standard 1080p - the readability of texts and the display of the test graphics are good to very good, depending on the degree of scaling. The inevitable interpolation artifacts are minor. Even texts with bold letters remain legible.

... has been working intensively on issues and developments in the IT industry for over 20 years, both professionally and privately. As a freelance writer, test editor and photographer, he knows the requirements for a good display. He has been with PRAD since 2013.