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Figure 2: Output sequence of RAW data
9.4 Bilinear interpolation of color sensors (RGB Bayer)
For Bayer demosaicing in the camera, we use bilinear interpolation:
Figure 3: Bilinear interpolation
1. Interpolation of green pixels: the average of the upper, lower, left and right pixel values is assigned as the G
value of the interpolated pixel.
For example:
(G3+G7+G9+G13)
G8 = --------------
4
For G7:
(G1+G3+G11+G13)
G7_new = 0.5 * G7 + 0.5 * ---------------
4
2. Interpolation of red/blue pixels:
Interpolation of a red/blue pixel at a green position: the average of two adjacent pixel values in corresponding
color is assigned to the interpolated pixel.
For example:
(B6+B8) (R2+R12)
B7 = ------- ; R7 = --------
2 2
Interpolation of a red/blue pixel at a blue/red position: the average of four adjacent diagonal pixel values is
assigned to the interpolated pixel.
For example:
(R2+R4+R12+R14) (B6+B8+B16+B18)
R8 = --------------- ; B12 = ---------------
4 4
Any colored edge which might appear is due to Bayer false color artifacts.
Note
There are more advanced and adaptive methods (like edge sensitive ones) available if the host is doing this
debayering.
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