Most projection Tv's used separate red, green and blue CRT's with each CRT measuring 7 inches diagonally. Lenses expanded these 7 inch images to fill the large projection screens. A few years later, three other technologies offered different ways to project large, high-definition pictures. They are all "micro displays," which means that they create very small images -- typically less than 1 inch in diagonal -- that are then projected onto screens. Until recently, most micro display HDTV's displayed their images in the 720 progressive or 768 progressive formats.

Most high-definition plasma and LCD flat panels also display in the 768 progressive format. There are advantages to both the 1080 interlaced and 720p, or 768p formats. 1080i displays have about 2 million pixels and refresh half of them 60 times per second. Their advantage is that when there is not much fast action on screen -- which is true most of the time -- the two halves blend together well and the moving picture is smooth and seamless.The resulting picture has a fine texture that many describe as "film like."

The 720p and 768p formats display about 1 million pixels and refresh all of them 60 times per second. While these formats have only about half of the resolution, and therefore have a more coarse texture, there is no "second half" of the picture to blend in, so their pictures are always smooth and seamless, even with fast motion. 1080p displays provide the best of both formats. They have 2 million pixels and they refresh all of them 60-times per second. HDTV signals are not commonly broadcast at 1080p, and when they are, they do not refresh 60-times per second.

Therefore, these Tv's must include more sophisticated signal processing to compensate. Fortunately, they do and it works well. In short, 1080 interlaced broadcasts, the most common form, can easily be up converted to 1080p. While a bit more complex, the less common 720p broadcasts also convert well to 1080p. If you are considering purchasing a big screen HDTV, be sure to check out at least one model with 1080p. We're sure you'll be impressed.