Episode II: a less-"jaggy" Jar Jar
By Brian Dipert -- EDN, January 9, 2003
Some of you who read my editorial last fall on digital projection wrote and asked whether the aliasing artifacts I saw in Star Wars: Episode II might have come from the digital videocameras used to capture the images, versus the DLP (digital-light-processing) system used to display them (see "Jaggy Jar Jar," EDN, Sept 19, 2002, pg 28). The answer is: "probably not" for several reasons. First, if this hypothesis were true, those of you who saw Episode II via a conventional projection system also would have noticed the artifacts, because a digital video-to-film transfer can't create more detail than the original contained!
Also, computers created many of the scenes and the items within them, along with the opening and closing credits in which aliasing was very noticeable. These synthetic objects' infinite-resolution Bezier curves and varying-sized polygons—not the much larger CCD elements—were the fundamental building blocks that constrained image resolution. Finally, George Lucas used high-definition digital videocameras with 1920×1080-pixel resolution when shooting Episode II, whereas the DLP projector at Sony Metreon was a 720-line-resolution model. So, even if the projector had been perfectly calibrated, and I suspect it hadn't, it'd still be the "weakest link."
Your comments did stimulate a related question in my mind, though: Under what conditions would the videocamera sensors' pixellation be visible? In early December, I visited the local IMAX theatre to find out. IMAX's DMR (digital-remastering technology) converts the anamorphically squeezed 15.2×21-mm image within each conventional 35-mm film frame to IMAX's nonanamorphic 48.5×69.6-mm image format on 70-mm film for subsequent projection, interpolating pixels and altering the aspect ratio along the way. In the case of Episode II, IMAX had access to the original digital bits and didn't have to prescan the frames before conversion, as was necessary with past DMR-transformed films, such as Apollo 13.
The resultant images were impressive and almost completely free of the artifacts I'd previously noticed. The only aliasing I saw—probably because I was looking for it—was a slight "shimmering" along the diagonal edges of moving objects with significant luminance variance from their background, such as a white ship moving against black space. The most disappointing aspect (pun intended) of my IMAX experience was that DMR transformed the original film's 2.35-to-1 aspect ratio to a nearly square frame, chopping off the sides of scenes so that the result would fill the huge IMAX screen. Then again, I own a wide-screen TV and, even before its purchase, preferred to watch letterboxed versions of movies. Different strokes for different folks.
IMAX, 1-408-253-0441, www.imax.com.
