How does up-converting standard DVDs work?

Answer 1

The technical details of how it is done are much too complicated to explain here. It is a form of digital processing called sample-rate conversion. A standard DVD picture is sampled at 480 vertical points and 640 horizontal points. Sample rate conversion changes that to 720 x 1250 or 1080 x 1920 points (for widescreen HDTV displays). However, no additional detail is added, but the result can look better because of fewer losses of detail in the processing of the image after conversion.