What it is

The X3 chip is an imaging chip developed by Foveon. It was finished late in year 2001, but wasn't launched until the beginning of year 2002, due to patent trouble.

The special thing about the X3 is that it, instead of having the imaging sensors next to each other, like a CCD array has, it has three layers of sensors built on top of each other. This means that the colour can be more precise, as the colour samplings will be from the same spot in the picture.

Why it is an important invention

In the past, CCDs in digital cameras have had problems with moire and other peculiarities. The theory has been that this has been mainly due to bad lenses and the fact that the CCD chips have the sensors next to each others.

This means that the X3 chip is the first real breaktrhough in the imaging chip industry since the late 1980s, when the CCD chips were updated significantly.

Because the sensors now are getting stacked instead of being put in arrays, chances are that this means that we finally will see prosumer cameras in the 10-20 mpx range.

The layered sensor system works because of the different depths that different frequencies of light will penetrate silicon; sensors at different levels pick up different colours.

  • dead pixels are a thing of the past - Most ccd chips have a weakness known as dead, or stuck pixels. These show up as pixels either alight in one particular colour (usually green or red), and might disturb an image fairly much. With the X3, pixels that are stuck will have three colours of the pixel illuminated at the same time, something that more easily enables the chip to exclude these pixels.
  • Cheaper - In theory, because the X3 is significantly simpler than a CCD chip, the X3 could become a lot cheaper - making digital cameras and camcorders cheaper.

The Name

"The name X3 comes from a unique capability that the Foveon X3 technology brings – the ability to capture three colors at each single pixel location. Foveon X3 image sensors capture the full color of an image without using a color mosaic filter and without the expense, complexity, and limitations of multi-chip systems such as a 3-CCD
camera or a multi-shot system." (from the Foveon press release)

Other reading

digital camera - CCD - CMOS