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SPOTLIGHT ON ISF CALIBRATION by Shane Buettner Calibration Sensation! These days you can't read a whole lot on the subject of home theater displays without seeing references to the ISF, "ISF Calibration," or "gray scale calibration." This may be Greek to some of you, while others may already be considering paying for these services and may be trying to weigh out the potential benefit vs, the cost. I thought it would be helpful to many of you out there to give an introduction to the above terms, and provide a first-hand account of the experience of having an ISF-certified technician perform these services. A guy named Joe The ISF (Imaging Science Foundation) was co-founded and (until recently) run by Joe Kane, a man with an extensive background in video display research, with Eastman Kodak, and film-to-video transfer, among other things. Joe, along with Joel Silver, started the ISF to help people achieve the best possible performance from their displays by adhering to the "rules" of the NTSC (National Television Systems Committee) television system. The ISF trains and certifies technicians, engineers and manufacturers to this end, teaching them to calibrate displays in adherence to the performance standards established by the creators of the NTSC system. For a fee, usually between $175-1000, these NTSC doctors make house calls, coming to your home to get your display working to the potential inherent in the NTSC system. The low end of the price spectrum represents direct-view 4:3 sets, which aren't as complex to calibrate. 16:9 sets, RPTVs, and front projectors are more complex devices in terms. The more complex the display, the more time, energy, and expertise is required to get the job done. I have Video Essentials, why do I need a full calibration? Out of the box most displays fall woefully short of their performance potential. Most displays are made to stand out in a brightly-lit showroom, the worst of viewing conditions. Manufacturers turn up the white level (contrast,) color levels, and even sharpness far beyond what is correct in order to turn consumers heads their way when the consumer is looking at a wall of 50 other TVs. Using Video Essentials (or Avia) to tweak your display's picture settings is certainly a step in the right direction, but this will not change the most critical aspect required for a good NTSC picture: proper color temperature. Too Hot for TV? NTSC standards dictate that your display maintains 6500Ò Kelvin color temperature across the entire gray scale, from white to black. If your gray scale is not correctly established, you will not achieve the true color fidelity and performance attainable in the NTSC system. Gray scale calibration can be achieved only by a properly trained technician using the proper tools. Your display's service menus must be accessed and the gray scale must be adjusted with a Philips color analyzer, or a device of at least equal accuracy. That being said, there are still some things to keep in mind. Some displays have color temperature settings, accessible by the standard menus that claim to be NTSC standard. Very few of these settings, if any, are 100% on the money. Most deviate from 6500Ò at least a bit, and some are not even respectably close. Also, some displays are simply incapable of properly tracking a 6500Ò gray scale across the entire color spectrum. Changes in illumination result in deviation, with color accuracy shifting with picture material. This is inevitable to some degree, but a properly trained technician can still get your display as close as possible to the goal of NTSC standard, but you need to find this mechanic first. A Good Mechanic Ask anyone and they'll tell you a bad mechanic is worse than no mechanic, and the same applies to the technician that works on your display. Accessing service menus and the adjustments that can be made in that fashion is serious business. If your technician doesn't know what he's doing, he could do far more harm than good to your display and its picture quality. So how do you know who to choose? First, insist on an ISF certified technician. The ISF is the only organization that I'm aware of who trains technicians to attain the inherent potential of the NTSC system, and says this is how it should be done. With this certification, you can take for granted that the Tech that comes out to your house has been trained properly and in accordance to ISF guidelines. You can contact the ISF directly at 561/997-9073, and they will refer you to the dealer closest to you that offers ISF trained and certified staff. Second, ask even an ISF certified technician how much experience he has calibrating displays of your type and brand. If you just stepped up to a $30k front projector you don't want to give your tech his first experience with front projection. Also, all brands have their own idiosyncrasies, and it would be best to employ someone very familiar with your brand. Third, check references! At your place of business would you hire anyone who walked in off the street without checking his/her references? I didn't think so, so why wouldn't the same apply to someone you hire to work at your house? Any technician should be able to supply contact information for satisfied customers that can give you an honest impression of the quality of work that technician has offered in the past. This can also confirm the above points, especially if the tech can refer you to someone with the same equipment you have. Bring out your best! "Bring out your best" used to be the tag line for one of Anheuser-Busch's beers, but the same could be said of Robert Busch of Busch Home Theater. A friend of mine in the custom install business referred me to Robert, who had done numerous calibrations on displays in the showroom he used to work in, as well as numerous client installations. He made it clear to me that Robert has vast experience with all makes and types of displays, including my own Pioneer RPTV. I had a pretty good idea that Robert Busch was the right guy when my friend told me to make sure to schedule the calibration for early on in the day. Robert is such a perfectionist that he'll stay to the wee hours of the night if that's what it takes to get the job done. And, if its still not done to his satisfaction he'll come back again the next day to get it done! On top of that, I had read Robert's work in Widescreen Review, where he has done reviews of display devices and video signal enhancers. Robert's background is in electronics, and he has been applying this knowledge in the home theater display realm for seven years. Upon contacting Robert, he immediately affirmed my confidence in his abilities and his experience with my particular display by offering to defeat the SVM in my Pioneer RPTV set. SVM is Scan Velocity Modulation. SVM ostensibly increases detail in your picture when the picture transitions from light to dark, and vice verse. In reality, SVM adds false detail to your picture, and creates a noise-like ringing around objects on screen, obscuring real picture detail in the process. A couple of years ago, when living in Colorado I could not find anyone who could accomplish this task on a Pioneer RPTV. The problem with my Pioneer in this respect is that SVM cannot be defeated in the main menu or the service menu, and requires physical circuit modification. I was very pleased and impressed to find someone who has done this before. Getting to Work Robert arrived promptly at 11am one morning to ply his trade. The tool box he brings with him includes a properly calibrated Philips color analyzer, a typical electrician's tool kit, and Austin Powers and the Nutty Professor on DVD, as well as a copy of Video Essentials, the ISF bible. First, he defeated the SVM circuitry in my as outlined above. Adjustments to be made later in the calibration process are better implemented having this inhibitor of real picture detail defeated. (Note that SVM can be defeated in the main menu or the service menu on many displays, which takes some time and money off the calibration compared to what my display required.) Defeating SVM took a good 30-45 minutes, and given that your display should be warmed up for a good 30 minutes before the other adjustments are made, we decided to take a short lunch break. Upon returning to the task at hand, Robert set about electronically and mechanically focusing each of the 3 (red, green and blue) CRTs in my RPTV. This is done by putting up the crosshatch pattern from Video Essentials and covering the two CRTs that you are NOT focusing so that only the CRT you are focusing puts up the picture. Electrostatic focusing is accomplished via the focus block, with Robert mechanically focusing each CRT using both of our eyes, his looking in from the rear of the set and me looking at the front. It was just like an eye exam. Robert would adjust the focus one way or the other and I would tell him which direction was "good" or "better," with Robert stepping around the front to satisfy himself that we hit as close as we could to optimal on each CRT. Blue was the toughest of the three, taking over 15 minutes to get the best possible result. Focusing the CRTs was not at all unlike getting a new pair of glasses with a new prescription. Everything was noticeably clearer and sharper. More on that later. Next, Robert got to work touching up the geometry and convergence. Geometry refers to shapes being correctly rendered by a display. In other words, if a circle is portrayed on the screen it is a shown as a round circle, not an elliptical egg shape resembling a circle. Robert also checked to make sure that my display was showing as much picture area as possible without retracing or flagging. As long as overscan isn't more than 5% in a particular direction, that is quite acceptable. My set was within this range and required no adjustment. Convergence refers to the fact that all three CRTs need to "converge" on the screen to make a picture, and the tighter your convergence is the sharper and more accurate the picture. (An obvious symptom of a mis-converged RPTV that you may have seen is white letters on the screen that have red or blue ghosts around each letter.) This is another adjustment that can be touched up via the main menu, but ultimately must be done in the service menu to get the best result. This also made using the crosshatch pattern on VE, this time with all three CRTs firing. You basically align the CRTs so that the crosshatch grid lines all over the screen, especially at the corners, are white with no ghosting of red or blue. Focusing and converging the CRTs is a fairly long and painstaking process, taking well over an hour in this case, and in some cases can take as long as 2-3 hours, or even more. This adjustment isn't required on a direct-view TV. Again, this extra time and energy is why RPTVs and projectors are more costly to calibrate. Shades of Gray Next, the money shot itself, the adjustment of the gray scale. My viewing room serves double duty as a living room, and as such has quite a few windows. I could not make the room completely dark, forcing Robert to use a dark, heavy blanket to build a tent around the TV. Draping the blanket over the top of the set and basically crawling inside it, Robert puts up the gray scale pattern from VE. He then holds the "head" of the Philips color analyzer flush to the screen on the gray block to measure the color temperature, making the adjustments via the service menu. Again, the goal here is that the gray scale properly tracks 6500Ò Kelvin across the entire gray scale. With every display there are compromises that have to be made in getting a gray scale to track as close to 6500Ò as possible. The key to optimizing any display's gray scale tracking is found in the ability of the technician performing the adjustment to know where those compromises should be made. "Don't Try this at Home Folks" With the gray scale adjusted to NTSC standard Robert set about putting the final touches on his work on my PRTV. Via the standard menu settings on my RPTV, he adjusted the color decoder. While most technicians would use the standard test patterns on VE to accomplish this, Robert relies instead on his vast experience in the field. With a wink, and the admonishment "Don't try this at home folks' Robert began adjusting the usual picture parameters: brightness (black level,) contrast (white level,) color, tint, and sharpness. The picture material used were the copies of Austin Powers and the Nutty Professor that Robert brought with him. Robert has seen these films displayed on properly calibrated professional monitors and knows exactly how they're supposed to look. Robert only used the VE test patterns to double check what he dialed in by eye. As you'll read below the results were stunning! Once Robert was finished everything looked dead-on. With the CRTs focused and converged, and SVM defeated, I'd say my picture was a good 25 % sharper than I have ever seen it. The increase in real picture detail was stunning, making the picture look very three-dimensional and film-like. With a properly tracking gray scale black level was perfect and shadow detail outstanding. Colors, flesh tones, in particular, have a "pop" that they've never had. The opening scene of Austin Powers was amazing. The colors were right, and at the same time the pale flesh tones of the actors emulating an "English" pasty look were perfect. The scene in Fifth Element where Leloo jumps into the futuristic air traffic looked so real it seemed you could reach your hand into the picture. On Heat, during the aborted robbery sequence, Robert DeNiro is immersed in black shadows, yet his scarcely lit facial features were detailed nicely. Buena Vista's anamorphic (yea!) widescreen transfer of the Shakespeare in Love looked gorgeous, capturing the beauty of the low-key cinematography and all of the intricate costume and production design. The Verdict The improvement afforded my RPTV by ISF calibration is not small. I've owned this RPTV for over three years, and only now am I realizing its full potential. It has never looked better. While the sharpness alone increased 25% I'd say the overall performance increased a good deal more, and this is a display that had been calibrated once before. Some displays would certainly see an even greater improvement. As I mentioned earlier, most new displays do not approach their full potential out of the box with factory settings. In most cases, calibration of a new display will represent a relatively low percentage of additional cost and will yield the optimum performance from your display that will not otherwise be achieved. The service provided has very real and tangible results, and while it can be costly the performance improvement easily warrants spending the money. As you've probably gathered, I enthusiastically recommend ISF calibration for any home theater enthusiast. Contact Info The ISF can be contacted at 561/997-9073. For those of you who may be reading this in Northern California, I give Robert Busch of Busch Home Theater my absolute highest recommendation. To get the most out of your display contact him directly: Busch Home
Theater Note: (1) Scan Velocity Modulation works by modulating the speed of beam current in a display as it "draws" scan lines across the screen. As a result, dark objects in light areas on screen appear slightly larger, while light objects in darker picture areas appear slightly smaller. The needle pulse pattern of Video Essentials illustrates this effect dramatically. |
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