TECHNO BYTES Q & A What is the Foveon chip? Demetrios J. Halazonetis, DDS, Dr Odont, MS Athens, Greece T he Foveon chip is a chip for digital cameras that uses new technology to capture higher- resolution images. Conventional digital cameras use a CCD or CMOS chip with many pixels. The pixels are insensitive to the color of incoming light, so, to capture color, each pixel is covered by a filter that allows light of only 1 color to pass through. There are 3 filters, 1 for each of the primary colors—red, green, and blue—arranged in checker- board fashion as shown in Figure 1. Note that there are 2 green pixels for every red and blue pixel. This is because the human eye is much more sensitive to green than to the other colors. The disadvantage of this scheme is that only 1 color is registered by each pixel. The other 2 colors must be guessed by interpolating from the neighboring pixels. Interpolation produces artifacts and results in a blurred image. The Foveon chip (http://www.foveon.net/X3_tech. html) uses a new silicon technology that can read all 3 colors at each pixel without filters. This is achieved by effectively stacking 3 pixels on top of each other (Fig 2). The result is a much sharper image. Currently, the only camera incorporating the Foveon chip is the Sigma SD9. It has 10 million pixels stacked in 3 layers, giving an effective resolution of approximately 3 megapixels. However, because there is no need to resort to interpolation, the images are even sharper than those produced by 6 megapixel conventional cameras. For reviews and comparisons with other high-end digital cameras, visit the following Web sites: http://www.dpreview.com/ reviews/sigmasd9/ and http://www.steves-digicams.com/ 2002_reviews/sd9.html. Assistant professor, Orthodontic Department, University of Athens Dental School, Athens, Greece. Reprint requests to: D. Halazonetis, 6 Menandrou St, Kifissia 145 61, Greece; e-mail, [email protected]. Submitted and accepted, November 2003. Am J Orthod Dentofacial Orthop 2004;125:390 0889-5406/$30.00 Copyright © 2004 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2003.11.006 Fig 1. Most digital cameras use 3 ﬁlters, 1 each for red, green, and blue, arranged in a checker- board. Fig 2. Cameras with Foveon chips effectively stack 3 pixels, 1 on top of another, resulting in sharper image. 390

What is the Foveon chip?

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TECHNO BYTES Q & A

What is the Foveon chip?Demetrios J. Halazonetis, DDS, Dr Odont, MSAthens, Greece

The Foveon chip is a chip for digital camerasthat uses new technology to capture higher-resolution images. Conventional digital cam-

eras use a CCD or CMOS chip with many pixels. Thepixels are insensitive to the color of incoming light,so, to capture color, each pixel is covered by a filterthat allows light of only 1 color to pass through.There are 3 filters, 1 for each of the primarycolors—red, green, and blue—arranged in checker-board fashion as shown in Figure 1. Note that thereare 2 green pixels for every red and blue pixel. Thisis because the human eye is much more sensitive togreen than to the other colors.

The disadvantage of this scheme is that only 1 color

is registered by each pixel. The other 2 colors must beguessed by interpolating from the neighboring pixels.Interpolation produces artifacts and results in a blurredimage.

The Foveon chip (http://www.foveon.net/X3_tech.html) uses a new silicon technology that can read all 3colors at each pixel without filters. This is achieved byeffectively stacking 3 pixels on top of each other (Fig2). The result is a much sharper image.

Currently, the only camera incorporating theFoveon chip is the Sigma SD9. It has 10 millionpixels stacked in 3 layers, giving an effective reso-lution of approximately 3 megapixels. However,because there is no need to resort to interpolation, theimages are even sharper than those produced by 6megapixel conventional cameras. For reviews andcomparisons with other high-end digital cameras,visit the following Web sites: http://www.dpreview.com/reviews/sigmasd9/ and http://www.steves-digicams.com/2002_reviews/sd9.html.

Assistant professor, Orthodontic Department, University of Athens DentalSchool, Athens, Greece.Reprint requests to: D. Halazonetis, 6 Menandrou St, Kifissia 145 61, Greece;e-mail, [email protected] and accepted, November 2003.Am J Orthod Dentofacial Orthop 2004;125:3900889-5406/$30.00Copyright © 2004 by the American Association of Orthodontists.doi:10.1016/j.ajodo.2003.11.006

Fig 1. Most digital cameras use 3 filters, 1 each for red, green, and blue, arranged in a checker-board.

Fig 2. Cameras with Foveon chips effectively stack 3 pixels, 1 on top of another, resulting in sharperimage.

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A Brief History of 'Pixel' - Foveon

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