Making something out of nothing

It's a real phenomenon

One of the most often confused concepts is the idea that upsampling DVDs to HDTV resolutions will make DVDs look as good as HDTV. It doesn't seem as if this is possible -- the data is not present to begin with. The real answer is that while an upsampled DVD isn't as good as true HDTV, it will look better than a straight 480 progressive lines of resolution. Here's why…

HDTV-ready CRT

Like a CRT PC monitor, an HDTV-ready CRT can sync at multiple resolutions. The catch is that the electron beam is not designed to change in size depending on the resolution (it changes but not by design). Suppose you have a 19" monitor running at 1280x1024 or 1600x1200. While reading this webpage, look at the white background. Get as close to the screen as you can to study the white. Now, change your monitor to 640x480 or 800x600 (if you want 640x480 in WinXP, go to Control Panel, Display, Settings, Advanced, Adapter, List All Modes…). Now look carefully at the white background – you'll see horizontal black lines. Ok you can go back to your original resolution.

The white background of the webpage does not have any detail. However the monitor is designed to resolve a higher resolution than the 640x480 you were testing. The space between one horizontal line to the next is greater than the distance that the closest two lines the monitor can reproduce. At a higher resolution, your monitor produces a more film-like picture because you are reducing the dead space. This is true even though you are dealing with two progressive signals.

This is to say that irrespective of detail, since 480p is typically below the maximum displayed resolution of the TV, upsampling can provide improved picture quality even if there is no change in actual picture content. This is why you do not want to have your HDTV displaying a true 480 lines.

Simulated DVD source

Simulated HDTV source

DVD source displayed natively

DVD source line-doub