How to Calibrate a Video Display

Take your display as far as it can go toward full performance potential by performing TPV’s basic “front-panel” calibration

The idea for this article came to me while I was trying to help a novice perform a basic calibration of his display over the phone. A job I could do in person in less than five minutes with a couple of my own test discs seemed a far more difficult task when I tried walking this newbie through it long-distance. When the person on the other end of the line hasn’t even heard of the Digital Video Essentials or AVIA test DVDs, where do you go from there?
To your own movie collections, of course! With the proverbial light bulb flashing above my head, I asked this guy if he had any recent vintage DVDs with THX logos on the cover, like the Star Wars trilogy, Moulin Rouge, T2, Pirates of the Caribbean, or Adventures of Indiana Jones. Being a respectable hometheater nut, he had several around—just for awe-inspiring demos. And since he had kids, he also had Finding Nemo and The Incredibles on hand.
Now, if you’ve got any one of those movies on your shelf, then you too are in business. Following the DVD menu selections to the THX Optimizer menu leads you
to the tools you need to perform a basic “front-panel” calibration of your display—adjusting brightness, contrast, color, tint, and sharpness correctly. This will take your display as far as it can go toward its performance potential without a full ISF calibration.
Before You Get Started
There are many settings on your display billed as “enhancements” which do nothing but reduce picture quality. Scan-velocity modulation (SVM), flesh-tone or color “correction” of any kind, most forms of black-level expansion or detail enhancement, and many other dubious technological “improvements” are typically boondoggles. Find as many of these as you can buried in your display’s menus, and defeat them. The labels are often confusing, so follow this rule of thumb: If you’re in doubt, leave it out. Meaning, if it looks suspicious, turn it off.
Things you want to look for and engage more often than not are presets called “MOVIE” or “CINEMA” or something similar. These setting often turn off most if not all of the harmful “enhancements” listed above. Starting the adjustment process outlined below from one of these preset modes will usually yield the best picture.
Selecting either the MOVIE or CINEMA mode will most often select the color temperature that’s closest to the 6500K standard, as well. If it doesn’t, the correct mode may be identified by a variety of other names (the user manual for the display may offer some guidance). “WARM,” “LOW,” and “MIDDLE” are the usual suspects. Do your best to find the most appropriate color temperature setting, and engage it before you start.
White Had Better Be Right!
Pop one of these recent THX DVDs into your DVD player and look either at the main DVD, the “special features,” “options,” or set-up menus to find the THX Optimizer logo. Click on it and select VIDEO TESTS from the Optimizer menu. You’ll now be on the CONTRAST/PICTURE SET-UP page. The menu offers its own explanation of what the pattern represents and how to use it, but let me translate: This pattern allows you to establish the proper level of white in the image. The control you’ll use on your display to perform this adjustment is likely labeled CONTRAST, as misleading as that is. (As you’ll see, there’s a lot more to true contrast in an image than cranking up the white level!)
Click PLAY TEST and you’ll see a pattern consisting of eight boxes of varying intensities of white, all of which are high in “Average Picture Level (APL).” The idea here is for you to turn up the white level (CONTRAST) on your display until you can no longer distinguish among the boxes, turning the entire pattern into a uniform white box (see illustration). What you’re witnessing here is a classic example of what we call “white crush” in our reviews. Detail or distinction between varying shades of white at the upper end of the grayscale has been lost, or “crushed” out of the image. After you’ve turned up CONTRAST to the point where such crush occurs, you then back the adjustment down until you can see the eight boxes again.
Sounds easy, doesn’t it? Unfortunately, not all displays will crush white detail enough so that the eight boxes completely disappear. But don’t worry, there’s a second thing to watch for, and something that you should be aware of and look for even if your display does turn the pattern into a uniform white box: color shift in the brightest of the eight boxes. CRT-based displays are notorious for this, but I’ve seen it recently with fixed-pixel devices, too. Most often, the projector or display will start to poop out when trying to generate enough blue to reproduce high-APL whites at higher CONTRAST settings. When this happens you’ll see the bright white areas of this pattern turn a bit yellow. Again, back the adjustment down until the “color” appears white again. In some displays if CONTRAST is set too low, the white will turn a bit red. (Keep in mind that many displays ship from the factory tinted too blue, and that a correct white-level setting may look a touch red to you initially.) You should be able to see these color shifts easily when viewing the pattern and running CONTRAST adjustment up and down. The sweet spot is the point where there’s no red or yellow tinge in the bright white boxes and all eight boxes are visible.
Guidelines for where CONTRAST is set properly on your display will vary, but the above procedure is your best guide. Trust your eyes. As a point of reference, after adjustment it’s relatively rare in my experience with typical consumer displays for CONTRAST to be set above the 50% point in the possible range of contrast settings, so don’t be nervous if the “correct” setting is quite low.
Back in Black
From the CONTRAST pattern chapter, skip forward and you’ll come to the BRIGHTNESS/SET-UP pattern page. BRIGHTNESS is not the most logical name for the adjustment on your display that affects black level; nonetheless, that’s what it’s called. The purpose of this pattern, and others like it, is to present areas of an image that are just above, or just below, the threshold of absolute black in the signal itself. How you use this pattern depends on whether your DVD player can display signals below black. Whether it can or not, the idea is that you should be able to distinguish between the charcoal-colored areas of the pattern near absolute black and absolute black itself. If you can see the difference between absolute black and 2% above black, you’re going to see all of the shadowy details that you’re supposed to see in the dark scenes of movies—and just as importantly you won’t see the parts of the image the film-makers intend to be shrouded in darkness. In other words, black level should be low enough so that black is black, but not so low that details near black are “crushed” or obscured.
When you play this test, the center of the pattern is a charcoal-gray THX logo. Turn the BRIGHTNESS adjustment on your display up high enough so that the “drop shadow” behind the letters is revealed. If you can’t see the drop shadow, check your DVD player settings to make sure that the player is adjusted to display below-black information. Unfortunately, manufacturers use different words to describe this adjustment, and those words seldom are: “Pass Information Below Black.” Some players will offer a choice between a 7.5 IRE and a 0 IRE black cutoff; some offer a “lighter” or “darker” setting. Choose the setting that makes the blacks blackest. If your player doesn’t show the drop shadow no matter what you do, don’t panic. The THX pattern allows you to set black level correctly whether or not your player displays “blacker-than-black” information.
In cases where you can see the THX drop shadow, lower the BRIGHTNESS control until the drop shadow just blends into the black background of the pattern, disappearing entirely— and you’re done. If you can’t see the drop shadow, look at the rows of black boxes at the top and bottom of the screen. There are seven of them. Lower the BRIGHTNESS control until you can just barely make out the seventh box. (This box is just slightly above black.) When you can just make it out, you can be confident that you’re seeing the distinction between barely-above black and your DVD player’s absolute black, which is now represented by the black background of the pattern. You’ll also be seeing as much shadow detail as your DVD player and display can extract from the signal they’re being fed. As a guideline, most displays will be properly adjusted for black level at BRIGHTNESS control settings well below 50% of the range. Some displays will be adjusted much lower. Again, let the pattern and your eyes be your guides, not an arbitrary presupposition about which number setting you think should be right.
Black and white levels are interactive. After you’ve set the black level, chapter-skip backward and re-check the white-level adjustments you made, and if you touch that up, also touch black level up again before moving on.
In Living Color The next item in the THX Optimizer set of video test patterns is the COLOR AND TINT SET-UP. Your set’s COLOR control adjusts the intensity (amplitude) levels of the primary colors of red, green, and blue, while TINT/HUE adjusts the intensity of the complementary colors (yellow, cyan, magenta). These two adjustments are likely to be named correctly in your display’s menus. To set these adjustments properly with this pattern, you need a blue filter, which you can purchase from a photography store, or a pair of blue goggles, which you can buy from THX.com. An easier way—and a way you may inclined to follow if you’re particular enough about picture quality— is to buy a copy of one of the dedicated test-pattern discs now available, such as Joe Kane’s Digital Video Essentials (my choice). This disc comes with a set of red, green, and blue filters.
If you’re willing to buy the blue filter, the instructions are simple. Looking through the filter run the COLOR control on your display up and down until the “color” words in the pattern are a uniform blue (see illustration). Do the same with TINT. Done deal.
If you don’t’ have a blue filter, and don’t want to go to the trouble of getting one, my advice is simple. There is one thing you’ll see in every feature film (or video) that you can use to adjust color properly—flesh tones. If you need a reference, look at the person next to you. As you watch movies, adjust COLOR until the flesh tones look right. TINT is harder, but often can be left at the default position without deleterious effect. The movies I use most often to dial in flesh tones are the opening sequences of the first two Austin Powers movies and Shakespeare in Love. In these films, the characters’ complexions are fairly pale, with just a hint of rosiness in their cheeks. Make their skin tones look that way, and your color won’t be far off.
Look Sharp! But Not Too Sharp…
The last page in the THX Optimizer VIDEO TESTS menu I’ll direct you to is called MONITOR PERFORMANCE. While some color touch-up information is provided, the key aspect of this pattern is the ability it gives you to use the frequency- burst area (look for the big white arrows) to adjust the sharpness of your display. Another misunderstood (and often overused) adjustment, the SHARPNESS control on your display cannot magically increase real resolution in the signal to make the image sharper. Think of the sharpness pattern more like an equalizer—it boosts certain parts of the frequency spectrum of the signal to emphasize (or over-emphasize) them. SHARPNESS is typically a coarse adjustment that bumps up what is essentially the upper midrange of the signal, which can make the image appear sharper and more detailed, but often at the expense of adding unwanted artifacts.
The frequency-burst section consists of a long row of vertically aligned black and white bars. Look at the far right area of the burst where the lines are smaller and more closely spaced. As you run the SHARPNESS control up, you’ll see this area of the pattern soften and blur (see illustration). At this point, you’ve actually “sharpened” the picture so much that fine details are being obscured, softening the image! I know that’s not quite intuitive, but as you perform this test you’ll see this effect even more clearly than it appears in our illustration. Back the SHARPNESS control down just to the point at which the fine lines in the right section are sharply defined again, and SHARPNESS should be set correctly.
I’ve corroborated this pattern with program material, and I like using it to set the SHARPNESS control. In addition to the softening and blurring of the image that comes with setting SHARPNESS too high, you will also see hardened, artificially sharp or edgy images in movies. Often, whitish halos can appear on edges as well. DVDs are often over-enhanced with artificial sharpness of their own, so any additional grunge added by the display via the SHARPNESS control detracts from a natural-looking image. Previous “sharpness” patterns used black vertical and horizontal lines, with some diagonals. The trick used to be to watch the black lines and run SHARPNESS up until white-edge halos become apparent around the black lines. This method is still effective, but the THX pattern seems to correspond closely with what you see in program material.
The other patterns in the Optimizer menu are selfexplanatory and allow you to make sure your TV and DVD player are operating at the proper aspect ratio. I’m going to go out on a limb and guess that the people who read this magazine know to set their DVD player’s aspect ratio to match the shape of their TV. However, if you’ve got a doubt, keep going. The Optimizer also features a test clip from the film.
Within the THX Optimizer VIDEO TESTS menu of The Incredibles is another selection called ADVANCED. The single pattern here was co-developed by Pixar and THX, according to the latter’s Web site, and includes a multipurpose pattern that allows an alternate method of adjusting white and black levels as well as gamma curve. The procedure is documented clearly at THX.com. Aside from the fact that many displays don’t offer any adjustment of gamma, I personally think if you’re ready for a greater level of sophistication in display calibration you’re ready for a copy of Avia or Digital Video Essentials, or perhaps even ready to call in an Imaging Science Foundation (ISF) technician.
Don’t Let My Dogma Bite You—Let Viewing Be Your Ultimate Guide
Once these adjustments are made to your set, it should come as close to optimal performance as it can get without an ISF tech taking it further. You can be confident at this point that any serious deviations you see are in the program material, not the display. You should also be amazed how much depth and dimension you’re seeing with the best program material now that you’ve got the proper foundation of deep blacks, that whites are crisp and bright but aren’t blowing out any detail, and that sharpness has been tamed so that all the detail you’re seeing is pure and natural, not etched and over-enhanced. However, I want to conclude with one piece of practical advice. Every time I perform these adjustments—even after I calibrate a display with a color analyzer—I double-check my results and touch them up as necessary with movies on DVD that I’m familiar with. This is a must for me, and I suggest you do the same. If you don’t like the image you see, season it to your taste. Don’t live with a picture you don’t like because someone else decided that’s how it should look. Your set won’t be quite as useful as an evaluation tool if you deviate too far from the “right” settings, but I think most people stay within reason when adjusting to taste.
That said, I’d expect most people’s “touch-ups” would be in black and white levels, and occasionally sharpness. (Color shouldn’t be turned up high enough to make everyone look sunburned, but the other settings are more negotiable.) The adjustments described above are most suited, in my opinion, to watching movies in a darkened room. However, people often want a little more white level and/or a little less black level for watching TV during the day. No big deal. If your set has multiple memories use them to save picture settings optimized for both viewing environments. At the very least, most displays allow separate memories for separate inputs—thus your DVD player and your cable TV/satellite box will have separate memories adjustments anyway.
Also in regard to black and white levels, with certain fixed-pixel devices I’ve seen (DLP projectors to plasma panels), I’ve preferred the image with the white levels set slightly high and/or black levels set slightly low. Even though some detail is inevitably crushed, some of these displays are so limited in absolute black levels that images lack “snap” or contrast if the display is set up by the book. Ditto for the standard settings of the SHARPNESS control. If your display simply looks too dull, and the only way to get any detail from it is to run SHARPNESS up all the way, by all means, do it! I’ve seen situations where the artifacts that result from running the SHARPNESS a little high are nowhere near as bothersome as the flatness of the picture with SHARPNESS in the “correct” setting. And most of all, enjoy the movies!