Seal Of Approval

THX-certified is a term well known in the audio and cinema world. Whether attached to a well designed movie theater, or a piece of audio gear that performs to a certain standard, THX has come to be synonymous with higher performance. Recently, THX started certifying video displays as well.

Curious to find out what THX looks for and how they test displays, Editor-In-Chief Geoffrey Morrison and I arranged to visit THX at their headquarters.

Located in Marin County, just north of San Francisco, THX is not far from Lucasfilm’s Skywalker Ranch, where the first THX program (a reference audio system for film soundtrack dubbing stages and movie theaters) originated back in the early 1980’s.

Our host, Dr. Michael Rudd, THX’s Chief of A/V Architecture, first introduced us to one of their display testing suites, which was equipped with an impressive array of exotic (and expensive) test gear, including an industrial strength computer used to develop and generate custom-designed high definition video test patterns.

As he ran through the various test patterns, he explained the purpose of each along with what they’re looking for performance-wise, and how they work with the manufacturer to fine-tune a particular set’s performance.

One might assume from the moniker “certification” that THX is more akin to a final examination, but in fact, they’re intimately involved during each set’s product development cycle, working with the manufacturer as a co-developing engineering partner, testing and advising along the way.

A number of those custom test patterns impressed both Geoff and I, including ones developed to evaluate a set’s high definition deinterlacing prowess, that actually permit a quantifiable score, as opposed to a more general “eyeball” score, such as the Silicon Optix HQV rotating bar.

Given that the majority of broadcast HDTV is in the 1080-line interlaced format, this is a hugely important area of concern, as poor deinterlacing to an HDTV flat panel’s native 1080-line progressive format can easily ruin the picture, with objectionable artifacts such as ragged jaggies on low-angle lines and edges, as well as smearing of on-screen graphics and text. Dr. Rudd pointed out that even with standard grade on-board video processors, sufficient “tunability” exists to permit the manufacturer to improve the TV’s deinterlacing ability, in order to minimize artifacts to their lowest levels.

Higher end displays may be equipped with a deluxe video processor from the likes of Faroudja or Silicon Optix, but with popularly-priced sets, that isn’t usually an option. Regardless, THX works with the manufacturer to extract the maximum performance out of whatever chip sets have been specified.

Another custom THX video test pattern deserves mention—a blue-only image with varying luminance intensity. This pattern is used to evaluate a display’s gradation performance, the better to see if the set has any issues with so-called “banding” artifacts, a common problem with digital displays. Blue was chosen as it is the one primary color that is both low in luma (intensity) and high in chroma (color value) and if a set has issues with gradation artifacts, this test pattern is ideal for evaluating same.

We then spent some time with the LG and Panasonic sets, arrayed as a trio with one Panasonic 50” and LG 60” and 50” offerings. We were shown a highly specialized piece of test gear, an Imaging Photometer, which takes snapshots of the screen and outputs directly to a computer, which allows for critical and objective evaluation of pixel-on/pixel-off behavior and picture uniformity, among other things.

Here we were able to see that even after fine-tuning, the three sets looked remarkably good, but there were still some discernable differences, such as black levels. Dr. Rudd agreed that it is somewhat difficult to make individual displays exactly match—there will always be a slight variability, even with fully certified models such as the LG and Panasonic samples.

Still, the picture quality from all three sets was exemplary, with a HD-DVD demo clip from the movie Phantom Of The Opera showing vivid and vibrant colors of the characters’ theatrical costumes, yet at the same time also showing natural-looking flesh tones, a result that is often mutually exclusive with most displays, especially with their default “store demo” factory picture settings modes.

To remind us that THX is still very much active in the audio arena, Laurie Fincham, THX’s Chief Scientist and VP of R&D, gave us a demo of another work-in-progress, the first THX Ultra2-certified in-wall subwoofer, BG’s new BX-4850.

The Ultra2 requirements include a rather stringent 105 dB maximum output level at all frequencies in a largish 3,000 cubic foot room, including the deep bass, which is where in-wall subwoofers typically fall far short of the mark. Using four dozen small-diameter, long throw mini-drivers that have the combined surface area of two 18” conventional subwoofer drivers, and powered by a hefty 2,400-watt digital multi-channel amplifier, the four module BG system sailed through the difficult second movement of Saint-Saen’s Organ Concerto, with room-shaking and note-perfect contra-bombarde low bass that was devoid of cabinet- or wall-induced artifacts.

Our day ended with an introduction to THX’s newest training regimen, their THX Video Systems Calibration course, which they began to offer earlier this year. A three-day affair, the training consists of one day of theory, and two days of hands-on video calibration training, using a dozen or more HDTV displays of various flavors, along with an introduction to the range of available color analyzers and signal generators that video calibrationists need in order to optimize picture quality in a client’s home.

The course concludes with a mandatory final exam, and it certainly isn’t for the casual participant, as you must score at least 85% in order to pass.

So what does the THX-certified display offer a potential buyer? It doesn't necessarily say that that specific display is the best-looking TV on the market. It does say that when placed into the THX video mode, the TV will perform at a certain level, which is above and beyond the level of the average display. This is the mode where the TV will replicate to the closest degree a professional HD monitor like those that are used in broadcast and mastering applications.  Which is to say, it's going to look pretty darn good.

On to an overview of Neural-THX Surround...