.:::. Tips for Better LCD Image Quality .:::.

Proper Connections and Configurations


Avoid Using the VGA Port

It amazes me to see how many people connect their LCD displays using a VGA cable. I was recently visiting a test lab at a tech company, who would test various systems using a 24-inch LCD display. Every time they dropped a video card into the system, they would carefully attach a DVI-to-VGA dongle to the graphics card, attach a VGA cable, then connect the card to the VGA port on the monitor. All this, despite the fact that the monitor had both HDMI and DVI inputs. I wanted to gouge someone's eyes out.





Really, use the digital connection. You're avoiding a pair of D-to-A and A-to-D steps, for one thing, which will minimize input lag if you're a gamer.Newer displays may have HDMI or DisplayPort connectors. That typically means you'll need some type of connector adapter, unless your video card happens to have one of the other types of digital connectors. Eventually, graphics cards will all move to DisplayPort, but that will take several years.It is true that DVI inputs were problematic in the past, and you occasionally see very cheap monitors with poor DVI connections. In those cases, however, the VGA input is really no better.

This brings us to our next point.


Configure the Input Port Correctly

I ran into a weird issue recently with a high-end display, my NEC LCD2690WUXi. This has two DVI inputs, uses an H-IPS panel and can be configured to have superb image quality. I recently relegated this to the secondary display on my desktop, replacing it with its successor, the LCD2690WUXi2. (Yes, I'm a little bit nuts. You did know that already, right?)

I immediately noticed serious pixel crawl on the secondary display—enough to be quite distracting. I played around with monitor settings, changed out the DVI cable and tried several other things. I was just about ready to swap in a different graphics card, when I checked the resolution setting in the Nvidia graphics control panel.

Normally, I set resolutions through the Vista control panel. That usually just works fine. This time, though, I looked at the resolution setting in the Nvidia driver control panel and discovered that my secondary display was set to a refresh rate of 59.9Hz. Apparently, the Nvidia driver thought I'd attached an HDTV or some other device. Switching the setting back to a 60Hz refresh rate solved the problem.





So if you're experiencing annoying pixel crawl in normal text, check the refresh rate in your appropriate graphics control panel. It may be incorrectly set.


Control and Calibration


Aggh! The Eyes Bleed!

I'm always amazed when users pull a display out of the box, connect it up, turn it on, and just use it. Then a few hours later, they complain about eyestrain.Modern LCDs typically use some type of cold cathode or fluorescent light as the backlight; a few newer models use LEDs for the backlight. The displays with cold cathode or fluorescent backlights can be very bright—the luminance can be as high as 800 cd/m^2, although typical numbers are more like 300–400 cd/m^2. If you work in a normal office environment without a lot of bright windows nearby, that's too much. For gaming use, you ideally want a luminance at around 150 cd/m^2. For serious image work, 100 cd/m^2 is even better. You'll find eyestrain considerably reduced by setting your display to lower light levels, and often times, black levels are improved, increasing the apparent contrast of your display.The proper way to do this is with the brightness control, which generally controls the output of the backlight. One you do this, you may need to adjust contrast ratio to get a more pleasing picture. The NEC displays I use actually have a setting for 100 cd/m2, which is generally where I leave it.


Calibrate Brightness (Blacks) and Contrast (Whites)

Calibrating a display may seem like a task best suited for image quality geeks, serious photographers and video editors. Certainly, the type of detailed calibration that requires expensive sensors and software is overkill for most users. But if you're running Windows XP Media Center Edition, or have Windows Vista Ultimate or Home Premium, you have your own calibration tool. And it will only take you ten minutes.





The calibration steps consist of walking you through a series of three videos while you adjust your brightness, contrast, and color controls. Here's one example, the black level (aka "brightness").





This really does take just a few minutes, and the improvement in the visual quality can be amazing. However, as you're working through the calibration process, you may run into the problem of color temperature and gamma.


Check the Gamma Correction

We're diving into one of the more geeky areas of display tweaking, but it's worth mentioning. Gamma correction corrects for the fact that display output and our eyes are nonlinear decoders, while images themselves are often encoded linearly. What you'd like ideally in a PC display is a gamma correction of 2.2. Achieving this is more difficult than it sounds, since many lower cost displays don't allow you to tweak gamma.





Display control panels often have gamma settings, but in some arbitrary unit (like percentage). So the only thing you can really do short of using a calibration sensor is to tweak it with your eye to get something that looks correct. On top of this, the gamma for video cards really doesn't yield the desired gamma correction of 2.2 for PCs, so you still have to fool with it a bit.

Higher-end displays do allow you to set specific gamma corrections, but these aren't always accurate. Still, it's better than nothing.


Who is this Kelvin Guy?

Another thing to consider is gray scale temperature. Most sophisticated users reflexively set the color temperature (if the monitor has a specific setting) to 6500 degrees K, which is the NTSC standard, and roughly analogous to cloudy daylight. Bright daylight color temperatures are around 5500 degrees K, while incandescent light is about 2700 degrees K. Still, D6500 is a good setting, since it's well understood, and most video is shot with that in mind.

Alas, many LCD displays ship with the color temperatures cranked to ridiculous levels. We once got in a very high end, 30-inch display, which had an out-of-box color temperature setting of 9300 degrees K, which is a holdover from the era of bad CRT television.

Most displays that allow you to set the color temperature don't really let you set the actual number. Instead, you get euphemisms like "warm," "standard," and "theater mode." In those cases "movie" or "theater" mode should approximate D6500, but there are no guarantees.

Another nifty trick is to find a THX certified DVD, which comes with a pair of blue glasses. If you have DVD player software, pop the DVD in and walk through the calibration steps using the glasses. That will help you set the correct color temperature.


Native Resolution and Monitor Orientation


Use the Native Resolution

I'm always a little startled by how many users just run their systems with whatever display resolution is configured out of the box. I've seen people with pricey 24-inch, 1920x1200 displays running at 800x600 because that's what XP set the resolution at when the operating system was first installed.

It does take some understanding of the display control panel. But you'd think that with modern displays, which feed information to the system about their capabilities, that the OS would auto-adjust resolution. (MacOS users already know how cool this can be.)

Of course, one of the chief complaints I get when I set the native panel resolution is how tiny the text appears. You can, of course, configure Windows to use a bigger font (eg, 120 dpi rather than 96 dpi). This works well most of the time, but does break some older applications. But it's better than running a 1920x1200 display at 800x600!

Monitor Distance and Height

Many displays come with height adjustable stands. What you don't want to do is induce neck strain, either by always staring up at your display or down. But what does that mean? For example, a high-end 30-inch display may force you to crane your neck on occasion, just because of its sheer size.

Then there's the issue of distance. How far away should the display be? If it's too close, it's like watching a tennis match—you're constantly scanning back and forth to see the material on the screen. If it's too far away, it may be unreadable. A general rule of thumb is to sit with your hands on your keyboard as you normally would. Now extend your arm with your hand outstretched. Your forefinger should just touch the display.

As for monitor height, finding the best height is a compromise, but a rubric that seems to work well is to have your horizontal eyeline intersect with the highest line of text possible on the display. All this will vary a bit, depending on monitor size.

Cleaning and Poking: Be Careful!

LCD displays are fairly robust pieces of hardware, but can still be damaged. For example, never, ever use Windex, or other ammonia-based cleaners to clean the surface of your monitor. These types of solutions may actually damage the surface of the display. Instead, a damp clean cloth will do a fine job. If you have something that's really adhering to the surface of the display—like the time you spewed your coffee all over the monitor because of a particularly funny Web comic, for example—gently rub or use a fingernail. Don't scrub with a brush or other hard object.

In a similar vein, be careful when pointing at your monitor. In the days of CRTs, I had seen users vigorously stab at a document to make a point. Since a CRT is glass, all that was left behind was an oily fingerprint. But you can permanently mar the surface of an LCD by stabbing at it with a finger or pen.

Take a Break

This technically isn't a tip specific to the display. People tend to forget to blink when staring at PC displays. So you should take frequent breaks, and look away from the monitor. Better yet, get up and walk around. Another useful tip is to keep a small vial of eye wetting solution, and use it on occasion.

The number of users working daily with LCD displays is dramatically increasing. Taking a little time away will actual improve the image quality, because tired, dry eyes will only result in a blurry image.