Smooth Operator

Even as HDTV takes hold, there are people (including me) looking for the "next big thing" that will improve video's realism. My recent experience with InterVideo's popular WinDVD DVD-player program for PCs has shown me one of the possibilities.

Deluxe versions of WinDVD include Trimension, a software version of hardware technology called Natural Motion, originally developed by Philips for its TVs. Trimension attempts to eliminate image "judder," which is jerky motion, especially of images or parts of images moving at moderate to fast speeds. Judder is a fundamental characteristic of film - and once you know it's there, you can't avoid noticing it in movie theaters as well as with films on DVD. The jerkiness comes from film's too-slow frame rate: at only 24 frames per second (fps), moving objects simply aren't photographed often enough. There's a whopping good example of judder in the right-to-left pan 11 seconds into Chapter 11 of Star Wars - Episode II: Attack of the Clones (the diner scene). I initially noticed it at a digital-theater screening, and it survives on DVD. In fact, the DVD judder is worse since the jerkiness has an uneven rhythm (due to the "2:3 pulldown" method of showing films via video).

To eliminate judder, Trimension calculates enough interpolated frames between the actual frames recorded on a DVD to be able to show them all at 60 fps. Good frame interpolation is a technically difficult and sophisticated process, and it's impressive that Trimension runs smoothly on a PC (a 2.8-GHz Pentium 4, at minimum).

Smooth is also the word to describe the results. Old or new, B&W or color, animated or live action - if the original film was made at 24 fps, Trimension makes nearly all moving objects cross the screen with an almost surrealistic smoothness. While images containing no motion look precisely the same with the system on or off, it takes only a very slight movement - a turn of a head, the raising of a hand, a single step - to make the image look more lifelike than normal film. The effect is so pronounced that the latest version of WinDVD, v.7, includes a toned-down mode that introduces an even-rhythm, cinema-like judder ("2:2 pulldown").

Actually, Trimension makes films seem more like video, showing how fundamental judder is to the "look" of film. Trimension turns the fancy-schmancy handheld camerawork of The Bourne Supremacy into Survivor with fights and car chases. And if smooth, natural movement isn't always good for art, judder cuts both ways. A tawdry reality show might gain the visual gravitas of Citizen Kane if shot at 24 fps. Then again, nothing can help The Apprentice: Martha Stewart.

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