A Bayer filter is a color filtering array for RGB colors.

It uses subunits of four pixels arranged like this:

Green	Red
Blue	Green

There are two green sites for every red or blue site, as the cone cells in the human eye are more sensitive to green light than other colours.

An illustrated explanation of color image reconstruction

To reconstruct a color image from the data collected by the color filtering array, you need to fill up the blanks. The mathematics here is subject to individual implementation. In this case, we use Adobe Photoshop's bicubic interpolation to simulate the circutry of a Bayer filter device such as a digital camera.

This is the original image, made with Adobe Illustrator. If a perfect digital camera with perfect optical lens that can measure every pixel's exact R/G/B values, the resulted image will probably look like this.

This is a simulated sampling taken by a Bayer filtered sensor array. Each pixel only has a value of either R or G or B.

	Frame enlargement
Red	Green	Blue

A digital camera has certain circuits to reconstruct the whole image using above information. The resulting image could be something like this:

Frame enlargement of the original.	Frame enlargement of the reconstructed image.

As you can see, the reconstructed image looks good in low contrast areas. However, the edges of letters look pretty bad.

Calculating RGB values

External links

• The Color Filter Array FAQ (http://www.fillfactory.com/htm/technology/htm/rgbfaq.htm)