The latest great thing in home theater displays is the emergence of 1080p resolution displays. p stands for progressive, which means the screen fills all at once at 1/60th of a second, versus i for interlaced, which means every other line, then the other half of the full picture, each field displaying at 1/30th of a second.

At this time, there is no source for broadcast 1080p programming. Instead, we have 1080i: two interlaced fields make a frame, at 1/30th second for each field.

Finger it out!

Take your fingers and spread them apart. That¡¯s a crude example of interlaced. When you bring the hands together, you combine both fields and you get the whole picture (one frame). It happens fast enough that you don¡¯t notice the effect unless there¡¯s motion on the screen, then you might see a difference in the smoothness of the motion.

Progressive is all the fingers at once. 720p is fewer pixels, faster: 1/60th second per frame.

1080 = 1920 x 1080 pixels | 720 = 1280 x 720 pixels

Till recently, HDTVs were either 720p or 1080i. Most TV transmissions were 1080i. I believe ABC adopted 720p because it would have shown sports with better pictures. I also remember back when Panasonic Broadcast underwrote ABC (as 720p) ¨C or at least Monday Night Football. Fox and ESPN now also do 720P. The others are 1080i.

The new 1080p sets don¡¯t have the front end circuitry to actually receive that resolution. But, again, nothing is transmitting that res anyway. What the advantage is, is how these sets show 1080i ¨C they have the pixel count to do it without trouble. They deinterlace the transmission and present it full frame without throwing away any detail. A 720p set has to downconvert a 1080i signal. In that downconversion you can lose some detail.

(BUT) OH SAY CAN YOU SEE?

But there¡¯s a more important issue ¨C can you really see the difference in resolution between 1080i and 1080p? Tests of visual acuity to determine the resolution required of a television transmission system by the BBC¡¯s J.O. Drewery and R. Salmon determined that at 9 feet, a 50 inch screen at 720p¡¯s resolution will give you all the resolution you can see! At 9 feet, a 56 incher needs 1080i to avoid seeing the pixel structure.\r If you sit farther or closer, you may need more resolution.

1080i vs 720p: MOTION CHANGES EVERYTHING

Motion is different issue. If you want to see motion clearly, then live action 720p is what looks best, compared to 1080i. Here¡¯s why: the information content of 720p is about the same as 1080i, though what it lacks in spatial resolution, it makes up for in temporal resolution (because the picture is at 1/60th of a second, not 1/30th x 2.) On 1080i, this would show as flickered or jagged edges on bright horizontal objects (like in the background of a camera pan.)

The good news? As the retailers hawk 1080p, you might find a killer deal on a 720p set and not give up anything in what I¡¯ll call ¡®effective¡¯ picture quality to get it.

Bob Wood cuts through confusion and technical detail to offer a clear guide: what you need to know to shop wisely; how to then maximize the performance of your Home Theater system. His website, http://www.GreatHomeTheater.com has been called ¡°refreshingly easy to understand!¡±