A/V Veteran

We’ve been fortunate in the 1080p world in having a variety of test discs available. While a full calibration requires special test tools, such discs can tell you a lot about how your set performs and help get the basic picture settings right. One of the most popular of such discs, and one of the first, is Digital Video Essentials, shown in the photo here.

But while 4K with high dynamic range (HDR) is now here, there’s still a lack of test materials for this format, particularly the high dynamic range end of the equation. This is an issue not only for the average consumer, but for reviewers as well. To date, the HDR setup in all of our reviews of Ultra HD/HDR has been purely subjective. We like to think that we know what a decent picture should look like, but when we’re judging the HDR aspects of that picture, things become a little dicey. We’ve been generally impressed by what we see, but would be happier if we had the means to get the basic HDR settings technically correct and consistent. That would give us more confidence in our judgments about the set’s HDR capabilities, as well as the HDR program material we review.

It won’t be long before we have such test material. In a recent visit to Joe Kane of Joe Kane productions, I was shown a prototype of a UHD test disc that his company is preparing for release. It includes a wide range of new patterns, some of them well beyond what we’re familiar with from those 1080p test discs. The new disc will include materials for UHD (3840 x 2160) without HDR, UHD with HDR, and 1080p as well, so you won’t have to switch between discs constantly while running your tests.

One of the tests can determine the peak white output a set produces depending on how much of the screen is illuminated. In the past, test patterns have most commonly shown either a full white field or a white window, with the latter typically encompassing 18%-20% of the screen area. Sets sometimes differ in how much light they produce depending on this percent of screen fill. This was, in the past, an issue mainly with plasma sets (and before them, CRTs), due to power supply limitations. Such a sets had to reduce its peak output when filling the entire screen with a bright image.

LCDs typically didn’t have this issue, since they’re inherently brighter than plasmas. But with the requirements of HDR, peak brightness vs. degree of screen fill can be significant. Joe showed me a set of curves that tracked the peak white level of several sets. While this should be identical depending on the percent of screen fill, it was anything but. A dropoff as the amount of fill increased was seen on virtually all of them. This is expected, for reasons described above, and generally has no visible impact. But on more than one of these sets (none of them were identified —I’m not being evasive), the peak output was in the mid-fill range, dropping off not only at the top but at the bottom as well! The new test disc will let us test for this.

Shifting gears a bit, Joe Kane has developed, in conjunction with Medialight, a new backlight system, the Medialight 6500K Bias Lighting System. It consists of a string of LEDs that can be stuck on the rear of the set. They’re USB-powered, and dimmable with a remote control. This is in contrast to previous, dedicated bias lights, which were AC-line powered, non-dimmable fluorescents. The slender Medialight’s string of LEDs should also work on a wall-mounted flat screen set, though I’d argue that it will work best on a table-mounted set positioned at least a foot away from the wall behind. This will allow the light to spread more uniformly on the wall behind it. And while it will work against any wall, it would certainly work best if that wall were painted a neutral gray. A blue-wall, for example, will affect your perception of the set’s color.