All high speed digital video cameras, in common with most digital stills cameras, have a single image sensor, the surface of which is divided into a grid of light sensors. These sensor are only 'black & white' - they only measure brightness. To 'see' colour a red, green or blue filter is fixed infront of each sensor. On our cameras, the colour arrangement of these filters is in a particular pattern known as a 'Bayer' pattern. The light falling on each sensor, through its colour filter, is measured by electronics to produce a 'raw' computer data file of red, green and blue values. In the case of the Phantom HD, the file format is called 'cine raw'. Subsequent to downloading the .cine file, the raw data is processd into a sequence of colour images, usually .tif files, using a sophiticated set of rules (an algorithm).

A consequence of this technique is that when viewing finely detailed scenes, some algorithms are better than others at interpreting the fine detail: all algorithms generate 'artifacts' or errors of these finely detailed areas. At Pirate, we actually use this inherent fault for focusing - by using a focus chart containing fine linethe appearance of these artifacts on the chart indicates pin-point focus.

A great explanation of the Bayer Pattern by Sean McHugh, with pictures(!), can be found here.

Wikipedia entry with more links and info is here.