A major concern in digital photography is aliasing. This occurs when the original picture has a fine texture or a sharp contrasting edge.
A fine texture may show up as a moiré pattern (like two grates put over each other made of different size mesh), or a sharp edge may appear as a jagged outline. To reduce these situations, use anti-aliasing filters.
Using a discrete set of data points, interpolation constructs new data points for digital photography. RBG (red, blue, and green, frequently used in additive light models) are combined in various ways to reproduce other colors. Using a demosaicing algorithm, they construct new data points from existing data points.
A Bayer filter mosaic rearranges RGB through a color filter array (CFA). This is the usual method in most of the current digital cameras. The use of a beam-splitter, single-shot approach does not require anti-aliasing filters, nor do they use demosaicing. A raw converter program is required to interpret the data coming from the sensor to a full color image.
Each pixel needs three values -- one red, one green, and one blue -- because a single sensor cannot record these three intensities at the same time. A color filter array (CFA) is needed to filter the color for each pixel.
The Bayer filter is a mosaic pattern of light filters, repeating a 2x2 pattern, green are at the opposite corners, with red and blue in the other corners. The excess of green utilizes the human visual system, determining the brightness; use of more green creates a higher sensitivity to brightness than to hue or saturation.
A four-color filter pattern may be used; this includes two different hues of green, creating more accurate color. However, this necessitates a slightly more complicated interpolation process than the standard RGB filters. The color being calculated can be guessed (or interpolated) from the values of the surrounding pixels.