The Bayer decoder block takes an incoming 1 byte/pixel Bayer encoded data stream and produces a 4 byte/pixel RGB data stream. A 3x3 buffer is used to provide the pixel data. The process is very standard; it receives a 3x3 block of pixels and uses a linear or bilinear interpolation. The figure below shows a normal Bayer pattern and the corresponding equations.

As shown, a green pixel in a red/green row would average the left and right red pixels to produce its red value and the top and bottom blue pixels to produce the blue value. A red pixel on the same row would average the four blue pixels in the corners to produce its blue value, and the four green pixels to produce the green value.