Many LCD monitors now come with both an analog and a digital connection. What's the difference? Which one makes for superior image quality? ZDNet pits analog against digital in a connection smackdown.There are two major types of computer monitors: CRTs, which are based on the same 100-year-old cathode-ray-tube technology as the first television, and LCDs, which are based on newer, liquid-crystal technology.
Although CRT monitors are still optimum for some tasks, LCDs look slicker, take up less desk space, and can offer sharper image quality, and as a result, they have begun to dominate the market. Most CRTs offer only an analog connection, but more and more LCDs offer both digital and analog inputs. Which one should you use?
Let's take a step back. A CRT, or cathode-ray tube, monitor is an inherently analog device, while computers are purely digital devices. How does a twentieth-century analog appliance talk to a twenty-first-century digital machine?
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| Analog (VGA) input |
The graphics card converts the computer's digital signal to an analog one, which it conducts to the monitor via an analog cable. Without getting into too much detail, the CRT monitor takes the analog signal and uses electron guns to manipulate phosphors and, well, it turns the signal into an image (read more about how CRT monitors work here).
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| A video card converts a computer's digital signal to an analog one, which a CRT translates into an image. |
An LCD (liquid-crystal display), on the other hand, like a computer, is a digital device. Manufacturers are increasingly putting both an analog and a digital connection on LCDs. When connected via an analog connection, an LCD is vulnerable to the same distortions that affect CRT monitors. However, when connected via a digital connection, often labeled DVI (for Digital Visual Interface), no digital-to-analog conversion is required, and there should be no loss or corruption of the signal. As a result, when running at its native resolution, an LCD should give you a cleaner and crisper image than you'd see on a CRT.
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| Digital (DVI) input |
If your LCD has a digital connection, you'll need a graphics card that has a DVI-I or DVI-D connector to take advantage of it. You'll also need a DVI cable (many LCD monitors come with only an analog cable). DVI-D refers to a digital-only connection, and DVI-I means that the connector can carry either digital or analog signals.
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Ok, this is the same thing I see everywheres, but does a radeon 9500 pro and an Acer AL1715BM have high enough technology so that an analog signal is still "like" a digital one? The Acer above has the HyDis 20ms panel which seems to be the fastest today, even over 12mn panels. The Hitachi CML175SXW2B also is based on the same Hydis panel, but also has a DVI connection. I can get the acer for 500 canadian and the Hitachi for 609 canadian...do you think the extra 109 dollars + tax is worth the DVI feature.