Buying Guide
There are a number of different formats for high-definition, a TV which supports any one of these standards can claim to be high-definition (or HD Ready):
- 720p
- 1080i
- 1080p
The number part specifies the number of vertical lines. 720p is 720 vertical lines (and 1280 lines horizontally). 1080i and 1080p are both 1080 vertical lines (and 1920 lines horizontally).
HDTV are always widescreen, so having a horizontal to vertical ratio of 16:9
The letter "p" or "i" denotes "progressive" or "interlaced" respectively, which denotes how the picture is built up. With interlaced the image is built up in two passes, with every other line updated. With progressive scan a complete image is transmitted in each frame. What this means in practice is that progressive gives a smoother picture, especially where there is motion.