By Tom McNamara

i Ryan McVay/Photodisc/Getty Images

If you are connecting an LCD monitor or flat-panel television, VGA (Video Graphics Adapter) and HDMI (High-Definition Multimedia Interface) are two popular options. In theory, HDMI is superior but, in practice, this is sometimes not the case.

HDMI Basics

HDMI is a digital format, so there is no conversion process between a media device and a flat-panel display device. In addition to supplying high-definition video, it contains wiring that transmits uncompressed, multi-channel surround-sound audio.

VGA Basics

VGA is an analog format, so the conversion process can produce a small amount of reduction in image sharpness and color accuracy. However, this cable type does not transmit audio. If you want sound, you will need separate cables.

VGA Quirks

Many flat-panel televisions will not accept a VGA signal higher than 1366 x 768 pixels. This is sufficient for 720p HD, which is 1280 x 720 pixels, but not 1080p HD, which is 1920 x 1080 pixels.

Monitors and VGA

However, LCD computer monitors will accept VGA signals at 1080p resolutions. (The "p" refers to "progressive," which means that the image is refreshed all at once for more fluid movement on screen.)

Cable Length

HDMI encounters a "digital cliff" past about 30 feet, at which point the signal can degrade dramatically. VGA can go two to three times as far before you get image-degradation problems. However, you can obtain "extender" devices for both formats.