1080i or 1080p? What about 720p?

OVERVIEW
Chances are within the last few years you've been comparing your options for a new flat screen TV or other HD television. You've no doubt compared prices and specifications and found some significant differences in both - especially when it comes to HD resolution. This article reviews the technology differences and shows why it might (or might not) matter to you.

COMPARISON OF TECHNOLOGY OPTIONS
There are several TV formats currently available. Nearly all new TV's are sold in the 16:9 widescreen format in resolutions of either 720 or 1080 lines. The scale diagram below compares standard definition TVs (480 lines) to the newer 720 and 1080 line HDTV's. The diagram clearly illustrates the improvement in picture quality over the last few years.

PROGRESSIVE VERSUS INTERLACED
The "p" in 1080p and 720p and the "i" in 1080i refers to way in which the picture is drawn on the screen. Progressive scan televisions (denoted by the "p") draw every line of the picture you are viewing at once. In other words, with each scan of the screen the full picture is drawn. With interlaced televisions (1080i), every second line of the picture is drawn with each scan of the television screen.

Consider the picture to the left, which represents the lines on an HDTV. On an interlaced television like 1080i, the green lines on the picture to the left would be drawn in one scan and the blue lines on a second scan. With a progressive scan TV, both the blue and green lines would be drawn on each scan.

This essentially allows the television to operated at a 1080 resolution with half the data requirements of a full 1080p television.

HDTV SIGNALS
Currently, over-the-air HD signals in America are not broadcast in 1080p due to their large data requirements. Most HD signals are broadcast in 720p or in some cases, a highly data-compressed version of 1080i. Some satellite TV providers are broadcasting channels in 1080p.

DVD AND BLU-RAY MOVIES
Of the currently available movie disc formats, only Blu-ray discs have the capability of storing 1080p HD content. Regular DVD content is stored with a maximum resolution of 720 lines.

New technology aside, older movies and especially older TV programs are only as good as their original format.

VIDEO GAMES ON AN HDTV
Both X-Box 360 and PS3 are capable of rendering 1080p content when connected to the 1080p TV with an HDMI cable, but can display game content on any television at its native resolution. Wii consoles use only standard 480p resolution.

Be sure to evaluate all options and comparison shop before choosing that new HD TV.