Re: Audioholics Interview- THX Display Certification
Q&A With Dr. Michael Rudd, Chief of AV Architecture at THX Ltd.
It’s been a while since we last conducted a formal interview with THX and we decided to pick up the phone and speak with Michael Rudd about the new THX Certification Display program. THX Display Certification primary goals are to drive quality in manufacturing and help simplify consumer buying decisions. According to THX, having a single testing methodology and specification enables display manufacturers to standardize on one benchmark that is recognized by both industry insiders and consumers alike. We put THX to the test with a series of questions we had about this program to ensure it wasn’t just another logo branded on a product to pimp sales.
Many people recognize the THX brand from the “Audience is Listening” tagline and our work with AVR and speaker manufacturers. What they don’t always realize is that we’ve been working with the visual side of movies for many years. In fact, close to 90 percent of our DVD post-production work has focused on ensuring stellar image quality throughout the mastering and production chain. And we have been fortunate to work on some of the world’s biggest DVD releases, including Star Wars and many of the Disney-Pixar films. We also spearheaded the development of standards for video switching, transcoding and scaling on AVRs and preamps. But it wasn’t until a couple of years ago that we started playing a more visible role in HD consumer products with the launch of the THX Certified Display program with Runco, Vidikron and Sharp.
For the average HDTV shopper, finding the right display can be a daunting process. You have to navigate the various formats, technologies and marketing claims, not to mention the massive wall of HDTVs at your favorite electronics retailer. We believe THX certification offers a simple value proposition to the consumer: if a display or projector is THX Certified, it will deliver exceptional performance regardless of price point, brand or display technology. We also feel that creating such a standard of excellence allows manufacturers to differentiate their premium products from less performing, competitive offerings.
Delivering the very best entertainment experience is what our original mission was, and still is today. With today’s technology, there is little reason why every pixel created in the professional environment can’t be replicated in the home along with great sound. And with the THX Movie Mode, featured on all THX Certified HDTVs, we’re providing consumers a very simple way to experience this kind of quality.
[IMG]http://www.audioholics.com/education/display-formats-technology/MichaelRudd_Headshot001.jpg/image_mini[/IMG]When we started working on the display program, there was already a very experienced team of video experts in place from our work in DVD mastering. But, we made several additional hires, including engineers with credentials from some of the industry’s top flat panel display manufacturers. For this program to succeed, we felt it was necessary to have a team with a depth and breadth of experience, including intimate knowledge of post-production and consumer electronics. I currently lead the THX Display team. My background is a mix of audio and video applications in both the military and home theater sides of the business.
There are several key ingredients to THX testing and certification. We have great testing engineers and some of the best laboratory-grade testing gear in the world, including Quantum Data Signal Generator and Photo Research Spectro-radiometers. We also have very tightly-controlled testing environments, black rooms where stray light does not affect testing and a dedicated home theater lab. In addition, we use both PC and Mac-based systems for generating our proprietary test patterns in uncompressed HD.
The specification itself is divided into Device Performance and Signal Processing Performance, so we look at both picture quality and video processing. The testing starts during the early stages of product development. If we don’t get involved early, it can be difficult to make the necessary changes to the display before it goes into mass production. When the first pilot-run displays are available, they are tested in the THX laboratory. Usually the displays are accompanied by a factory engineer, who can adjust the firmware whenever it doesn’t meet some of our testing criteria. No display has ever passed the THX certification first time out-of-the-box.
[IMG]http://www.audioholics.com/education/display-formats-technology/THXLab_DSC0099finalCMYK001.jpg/image_mini[/IMG]The device measurements were developed in accordance to the SMPTE, IBU, VESA and ANSI guidelines and evaluate such things as a display’s brightness, contrast, uniformity, convergence and viewing angles. While these tests are based on recognized industry standards, we created our own methodologies for quantifying items like deinterlacing, scaling and motion conversion, areas that had been previously tough to pinpoint. We produced custom designed patterns to enable the repeated evaluation and quantification from product to product.
Today, many companies still rely on a set of “golden eyes” to judge a display’s signal processing abilities. We opted for a more objective approach. We created special animated test patterns to expose any weaknesses in a display’s deinterlacing, scaling and processing features. For example, our deinterlacing patterns use moving fields of alternating colors to identify how a display responds to moving content. The variety of testing materials and patterns are designed to allow us to actually place a numerical grade on signal processing performance.
We do have minimum requirements in all of the key areas that you mention and many more. Our black level, contrast and color gamut performance requirements are based on SMTPE research and recommendations, which are professional video standards for screening rooms. Because a big part of the THX certification is recreating the cinematic experience, we felt that defining levels within the professional industry specifications would be the best way to bring that experience to the home.
Yes and no. Yes, we are encouraging display manufacturers to support xvYCc, but no we are not yet requiring it for THX certification. We feel that xvYCC offers a compelling way to describe color gamuts which are larger than Rec.709. However, Rec.709 is still the mandated specification for HD mastering today and there is currently no home entertainment content produced in the xvYCC format. For that reason, the Rec.709 color gamut is required for all THX Certified displays. If this type of content were to become available to the consumer in the future, then the xvYCC format would be very valuable.
We consider THX Movie Mode to be the best out of box experience possible. And since we test and evaluate each product, this setting is consistent across all display technologies. THX Movie Mode sets the red, green and blue primaries (color management), the luminance, as well as the black level, the correct value of gamma and correct tracking of the white-point with gamma. We opted to use white point instead of color temperature, since it is more precise. Many of these parameters are not accessible to consumers even from the service menu. So, THX Movie Mode provides them a simple way to get the right settings with just a push of a button. In addition, THX Movie Mode ensures that a display complies with the HDTV standards and will present HD content correctly.
We do check the functionality of the HDMI input on THX Certified Displays. It’s important that a THX Certified Display is exceptional both in terms of video quality and compatibility with source devices. All THX Certified products, whether they are speakers or HD displays, are designed to be compatible with each other. Since HDMI has become such an important feature on new HDTV products, it is necessary for us to check the basic functionality.
We get this question a lot. And, the truth is, we never give out specifics about what THX testing has improved in a particular manufacturers’ product. It just wouldn’t be fair to our partners. However, I can address the question more generally. Since its inception, the THX Certified Display program has been adopted by LG, Panasonic, Runco, Vidikron and Sharp—all premium brands. Thus far, the areas where we bring the most value are improving uniformity performance, color primaries and gray scale, and signal processing. Regardless of the brand, we always find areas that can use some improvement.
It’s no secret that there are inherent differences between display technologies. So, creating one specification that works across all display categories was the biggest challenge we faced when developing this program. For example, a THX Certified LCD must meet the same, tough contrast requirements as a THX Certified plasma—without compromise. Even though our testing and certification is technology agnostic, we do pay closer attention to certain areas than others with specific technologies. We explore image smearing more extensively on LCDs, and rainbowing on single-chip DLP front projectors. The goal is to present a consistent, high quality viewing experience on each THX product across all categories.
[IMG]http://www.audioholics.com/education/display-formats-technology/THX_VideoTesting1001.jpg/image_mini[/IMG]The specification covers about 400 data points and close to 30 tests. We start by getting the color imagery correct, then work our way through contrast, brightness and standard user controls. The video signal processing tests are performed closer to the end of the testing cycle. Because we have been able to automate much of the data acquisition, testing can be completed in just over a week or so.
We have only one level of certification performance across all display categories.
Our standards for video signal processing were developed independent of any particular chipmaker’s performance claims. However, we have evaluated products from all of the major manufacturers that you mentioned, and as you might expect, we have found differences between them all. Because there is such a wide choice of settings, such as filter selections, one particular chip can work differently in different display products. For this reason, we have to work closely with the display manufacturer’s engineers to optimize the settings of a selected chip for a particular display model. We apply the same standards to all chip manufacturers and we have failed displays that contain processors which do not meet our standards.
We have two new lines of THX Certified plasmas from LG and Panasonic shipping in the next few months. The Panasonic PZ800 series, which features the 42-inch TH-42PZ800, the 46-inch class TH-46PZ800 and the 50-inch class TH-50PZ800. From LG, we have the PG60 Series, which in the US comprises the 60PG60 and 50PG60. This is exciting for us because these models will be the first THX Certified Displays available through traditional retail chains. Hopefully, Audioholics will get the chance to give them a good workout.