DVD upscaling

The average DVD player can output 720x480 (480i) pixel resolution. A progressive scan DVD player can output video signals 720x480 (480p).

480i = 720 pixels across 480 down. All the odd lines are displayed then the even

480p = 720 pixels across 480 down. Each line is displayed one after the other.

HD-DVD - upscaling

HD-TV outputs 1280x720 (720p) pixel resolution or 1920x1080 (1080i or 1080p)

720p = 1280 pixels across 720 down. Each line is displayed one after the other, in a progressive pattern.

1080i = 1920 pixels across 1080 down. All the odd lines are displayed followed by the even.

1080p = 1920 pixels across 1080 down. Each line is displayed one after the other.

Upscaling matches the pixel count of the DVD to the pixel count on the TV.

- information retrieved from http://hometheater.about.com/od/hometheatervideobasics/qt/dvdvidupscale.htm