Liquid-crystal displays (LCD), in the past restricted to notebooks, are now a reality for desktops. The three greatest advantages of this type of video monitor compared to traditional tube-based monitors (a.k.a. CRT, Cathode Ray Tube) are the use of less space on the desk (especially 17" models or bigger), less power consumption and 100% flicker-free, even with a refresh rate of only 60 frames per second (60 Hz). In this tutorial we will explain everything you need to know to make the right choice when buying a new LCD monitor.
The most important thing you need to know about LCD technology is that LCD panels have a fixed resolution. This resolution is called “native resolution,” “maximum resolution” or simply “resolution” and you must configure your desktop to that resolution, otherwise three things can happen, depending on the model of your monitor:
1. The image won’t be “sharp;” it will be blurred. You will see lots of squared areas, without any definition.
2. The monitor will centralize the image in the new resolution, reducing the image size and inserting a black frame around the image. For instance, if your LCD native resolution is 1280x960 and you decreased it to 800x600, this means there are 480 pixels left horizontally (1280 - 800) and 360 pixels left vertically (960 - 600). The image will be centralized and there will be 240 black pixels above and below the image and 180 blank pixels on the sides of the image.
3. The monitor will try to stretch the image in order to not show the black area around of the image, filling the whole screen. This is done through a technique called interpolation, which isn’t 100% perfect and thus you will feel that the image has better quality (definition) when the screen is configured at its native resolution, even though the elements on the screen (e.g., icons, letters, etc) will be smaller. In general you will feel that the image is slightly out of focus (blurred) when the monitor is not configured in its native resolution.
Because of this inherent characteristic of LCD panels you will have to choose an LCD monitor that has a resolution that you are comfortable with. The higher resolution isn’t always the better. With higher resolutions you have more space on your screen (in other words, more stuff will fit the screen at the same time) but icons and letters will be smaller. So for the average user a monitor with a higher resolution doesn’t always translate into a better product, it will largely depend on the application. If you only use your computer to browse the internet, write e-mails, use spreadsheets and word processing you will probably want to stick with a monitor with a lower resolution, because they are cheaper and won’t make your icons and letters to become very small. But if you run professional applications like video and image editing, then you will probably want a monitor with higher resolution and screen size.
If you are a gamer, you must buy a monitor that matches the resolution you want to play, otherwise the game will look like “blurred.” In other words, configure your game to run at the display’s native (i.e., maximum) resolution. All gamers know that when you increase the game resolution the performance lowers (because there will be more pixels to be drawn on the screen). If your game is running too slow, that means it is time to upgrade your video card. You can decrease the game resolution but, as we are explaining, you will hurt image quality.
Screen Size and Aspect Ratio
Screen size – which is the screen size measured diagonally in inches – has nothing to do with resolution. I.e. a bigger screen does not guarantee a higher resolution. In fact, it is very common to see big LCD monitors with resolutions that are lower than the ones used by smaller units. If you see a big monitor being sold cheaper than a smaller display you can bet that the smaller unit has a higher resolution that the big display. This doesn’t mean that the smaller display is better than the bigger one; it will depend on the application. People looking for more space on the screen (e.g., image and video editing) will prefer a monitor with higher resolution (even if it is a “small” monitor) while “normal” users may want to enjoy a bigger screen at a lower resolution, since the lower resolution will keep the icons and letters at a good size. Of course the “lower” resolution here is in comparison with the “higher” resolution used by the other displays.
It is always worth mentioning that you can increase the size of the icons and letters on Windows’ Control Panel.
Aspect Ratio is the ratio between the horizontal and the vertical sides of the monitor. CRT monitors and the first (and cheaper) LCD monitors have a 4:3 (i.e., 1.33) aspect ratio, meaning that the horizontal side has a length that is 1.33 (4:3) times the vertical side, and that the vertical side has a length that is 0.75 (3:4) times the horizontal side. Currently “widescreen” aspect ratios are becoming more popular, with 16:9 or 16:10 aspect ratios.
In the table below we list the most common aspect ratios and the most common resolutions for several aspect ratios. Monitors with different aspect ratios can usually at resolutions from other aspect ratios by adapting them.
15:9, 5:3 (1.66)
On this page we will explain the main features found on LCD video monitors and how to interpret them:
- Response time (a.k.a. performance): this feature measures the time the panel delays between switching a pixel from off (black) to on (white). This time is measured in milliseconds and the lower, the better. On a video monitor with a high response time you will see the screen blurred on fast animations (such as games) and fast movements on video playback. Today is easy to find video monitors on the 5 ms range and below, and you should buy a monitor with at least 5 ms response time. If you are into gaming, a 2 ms monitor is recommended.
- Brightness: This spec indicates how well you will be able to see images on your screen on a bright environment. This spec is measured in a unit called candela per square meter (cd/m2) and the higher, the better. For a typical office use, a video monitor with a 300 cd/m2 or 400 cd/m2 brightness is more than enough, but you will need a number far higher than this if your monitor will be exposed to direct sunlight or if it will be on an outdoors environment.
- Contrast ratio: This spec measures the brightness difference between the maximum white and the maximum black the monitor can generate. The higher this ratio is, the better, as you will be able to distinguish between more colors (i.e., better image quality). An LCD monitor with 600:1 rate, for instance, is better than a monitor with a 400:1 one. Units currently available on the market have contrast ratios between 400:1 and 1000:1. There is also a similar spec called “DC” or “Dynamic Contrast Ratio” that presents higher figures, see below. Some manufacturers announce the monitor DC instead of the static contrast ratio. You can’t compare dynamic contrast ratio to static contrast ratio. For example, a monitor with 5000:1 static contrast ratio will have superior quality compared to a monitor with 5000:1 dynamic contrast ratio.
- Dynamic Contrast Ratio (DC): Displays with this capability will lower the brightness from the backlight of the LCD display depending on the image being displayed to provide a better contrast ratio. Notice that this is a trick to improve image quality that doesn’t change the monitor’s real (static) contrast ratio. As explained, you can’t compare dynamic (DC) values with static values; they are incompatible. A monitor with a 1000:1 contrast ratio will have a better image quality than one with 2000:1 dynamic contrast ratio with only 400:1 contrast ratio. Some manufacturers only announce the DC ratio, especially when the monitor has a high DC but a low static contrast ratio. When you see monitors advertised with a contrast ratio measured on the thousands, you can bet that the manufacturer is talking about the dynamic contrast ratio, not the real (static) one. So compare static contrast ratio with static contrast ratio and dynamic contrast ratio with dynamic contrast ratio. Dynamic contrast ratio is a desirable feature but when comparing two units with the same DC, pick the one with the higher “real” contrast ratio.
- Viewing Angle: Depending on the angle between the user and the screen, the user won’t be able to see the contents from the screen. The viewing angle indicates the maximum angle the user can stay from the video monitor and still see the screen contents. Usually two numbers are given for this spec, one horizontal angle and one vertical angle, with some models having an upper viewing angle different from the lower viewing angle. Since most users will stay exactly in front of the video monitor, this spec doesn’t make much sense for the average user. But depending on the application (for example, you are going to hang a video monitor on the wall to be used to display information for people passing by or something similar) this spec can be very important.
- Connection: LCD monitors can use two types of connections, VGA (using a plug called D-Sub) or DVI-D. The first one is an analog connection, while the second one is a digital one and thus providing a better image quality. You should use the DVI-D connection for connecting your video monitor to your PC, but you are limited to the kind of connection provided by your PC. Currently all video cards provide two outputs, with low-end and mid-range video cards usually providing one VGA and one DVI output and with high-end video cards providing two DVI outputs. Unless you have an entry-level PC with on-board video that only provides one VGA output, you should use the DVI one. For more information on this subject, please read our Video Connectors tutorial.
- USB hub: Some monitors have an embedded USB hub. This device has nothing to do with the connection between the monitor and your PC mentioned above. This device is added to the monitor in order to make the life of users that have several USB devices on the desktop such as keyboard, mouse, webcam, digital cameras, etc easier. Instead of having several cables coming from your desktop and using several USB ports on your PC you connect everything on the USB ports from your monitor and connect just one cable from the monitor to your PC.
Originally at http://www.hardwaresecrets.com/article/Everything-You-Need-To-Know-About-LCD-Monitors/87
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