Foveon X3

Spatial resolution

Subsequent X3-equipped cameras have less aliasing because they include micro-lenses, which provide an anti-aliasing filter by averaging the optical signal over an area commensurate with the sample density. This is not possible in any color channel of a Bayer-type sensor. Aliasing from the Foveon X3 sensor is "far less bothersome because it's monochrome," said Norman Koren. In theory, it is possible for a Foveon X3 sensor with the same number of photodiodes as a Bayer sensor and no separate anti-aliasing filter to attain a higher spatial resolution than that Bayer sensor. Independent tests indicate that the "10.2 MP" array of the Foveon X3 sensor (in the Sigma SD10) has a resolution similar to a 5 MP or 6 MP Bayer sensor. At low ISO speed, it is even similar to a 7.2 MP Bayer sensor.