Despite all the technical comparisons that are so often made between video and film, one that is usually overlooked is the alignment of the colors. Color film actually consists of three photosensitive layers to sense the three different primary colors, with filter layers in between the light-sensing layers. A tiny pinpoint of the color purple, for example, would register in both the "red" layer and the "blue" layer in the exact same spot behind it.
Image sensors, by contrast, place color-sensitive pixels next to each other, in single-chip camera designs. (Three-chip systems get around this dilemma.) If you imagine a straight white edge, and look very closely, you'd see jaggedness from the individual red, green, and blue pixels that are all used to reproduce white.
A new image sensor claims for the first time to get around this problem by vertically stacking the red, green, and blue pixels. Intended for high end digital still cameras, with 14 mega-pixels, Foveon, creator of the "X3" image sensor technology, says it eliminates the color sampling artifacts found with other image sensors. See Image sensor intros include 14.1-MP vertically stacked RGB pixels. The new X3 sensor packs 14.1 million pixels, each 7.8m in size, into a 3-dimensional array of 2652 x 1768 x 3 pixels with an active image area measuring 20.69 x 13.79 mm.
As demonstrated in this Foveon demo, the X3 technology is also more light sensitive, utilizing more of the photons hitting the image sensor's surface.
The new X3 sensor makes its premier in the Sigma SD14 digital SLR. The sensor's maximum frame rate is five per second, too slow for video. For now.
But it's a trend worth keeping an eye on. X3 technology may ultimately bridge the gap between one-chip and three-chip imaging, and someday render 3-chip camcorder designs obsolete.