High Definition capabilities have truly become ubiquitous, but understanding HD is still relegated to elite geeks, until now.

LCD/Plasma HDTV Wall Mount, 37-63"
$13.95

High Definition Means High Resolution

When understanding high definition, the first step is to understand resolution, because where there's high resolution there is high definition. Resolution is simply a description of the number of pixels being viewed. Pixels are the smallest parts that make up a full video picture. High Definition generally starts at 1280 x 720 (aka 720i or 720p) pixels and goes up from there. This simply means that there are 1280 pixels if you counted them from left to right, and 720 pixels if you count from top to bottom, for a total of 921,600 viewable pixels. These days, the largest defintion available to consumers is 1920 x 1080 which is also referred to as 1080i or 1080p.

1080i vs. 1080p and Hz Explained

The 'i' in 1080i stands for 'interlace scan' and the 'p' in 1080p stands for 'progressive scan'. The Hz specification that goes along with that indicates how many times per second the video image refreshes. So a sample resolution would be 1080p30, or 1080p at 30 Hz. There is a big difference between 1080i and 1080p, but what is better?

The quick answer is that 1080p is much better than 1080i. With progressive scan (1080p), your TV will refresh every single pixel every time it refreshes, which is commonly 60 times per second (or 60Hz). With interlace scan (1080i) your TV will take the 1080 lines of pixels and only refresh the even lines at one time, and the odd lines at one time. So during each refresh only half of the pixels are up to date, and the other half is old by a microsecond. This can cause a very subtle blurring effect to the naked eye when viewing fast moving video.

Generally speaking, if your TV can not do 1080p, and you have to choose between 1080i and 720p, we'd recommend 720p probably. This is especially true if you have an HDTV that is 32" or smaller. Chances are you can't tell the difference between 720p and 1080p on a screen of that size.

Interfaces

There are four main High Definition interfaces that the majority of the public use: Component (RCA), VGA, DVI, and HDMI.

Component

Sewell 3 RCA (RGB) Component Cable, 10 ft.
$1.99

Component video generally uses three different RCA connectors for one single High Definition video signal. It is called component because it splits up the three components of video into three different connectors. This is in contrast to its counterpart, composite, which uses only one RCA connector to transfer a video signal, and the connector is typically yellow. Since component splits the video signal up into three connectors, more bandwidth is available than its single connector brother composite.

Component is an analog signal, and essentially splits the color video signal into Red, Green, and Blue signals, with black and white included in all three. Component can achieve resolutions from 480i to 1080p, but few HDTVs support resolutions this high through the component port.

VGA

VGA Monitor Cable, 10 ft
$3.95

VGA is a computer connector that uses the same type of analog signal that component uses, just in a single connector with 15 pins. VGA, or Video Graphics Array has been used in computers since 1987. It is a common mistake to assume that digital signals are better than analog. One advantage of analog is that there is a much more lenient distance limitation. With the latest advancement in VGA, also called QXGA, you can achieve resolutions of up to 2048 x 1536.

Although VGA is an interface used mainly for monitors and computers, it is also somewhat common to see VGA interfaces on select HDTVs these days. Converting from VGA to component is also pretty easy since the signals are already similar.

DVI

Sewell DVI-D Cable, Dual Link, 10
$9.95

DVI, or Digital Video Interface, uses a completely different approach to displaying video than its analog predecessors. It is a digital signal that assigns values to each individual pixel using advanced computing, assigning each pixel color and brightness values.

There are also some other versions of DVI that are analog signal friendly. Because of the big difference between the ways an analog video system and a digital video system renders images, the DVI interface completely seperates the two. DVI-I connectors for instance are 'integrated,' or simply include the capabilities of transferring both analog (the same signal used in VGA) and digital signals.

Since DVI is a video-only signal (and no audio), it is typically used as the digital video connector for computers.

HDMI

6 ft HDMI Cable, High Speed with Ethernet
$6.95

HDMI, or High Definition Multimedia Interface, basically took DVI and added audio, making an all-in-one connector that would be convenient for home theater systems. The older version of HDMI out there right now, or HDMI v1.2, uses the DVI video signal and 8 channel surround sound audio in one compact connector. A recent revision of HDMI (aka HDMI v1.3) upgraded the bandwidth to allow 10.2 Gbit/s transfer rates, or 340 MHz. This also allows for Deep Color Support, high definition audio, and more.