Image Processing Reference
In-Depth Information
fy
p
/√2
√2
p
B/W
1/2
p
G
R
G
R
G
1/4
p
R/B
2
p
BGBG
fx
1/4
p
1/2
p
GR R
G
p
BGBG
p
2
p
(a)
(b)
FIGURE 7.6
(a) Pixel square array with Bayer configuration color filter; (b) Nyquist frequency of each color.
Conversely, in the combination of an interleaved pixel array sensor and the Bayer config-
uration shown in Figure 7.7a, the G pixel configuration is a square array with the pitches of
√2
p
in the vertical and horizontal directions; therefore, the Nyquist frequency is 1/2√2
p
,
as shown in Figure 7.7b, indicating debasement to one-half of the monochrome case and
lower than the square pixel array sensor, while the diagonal direction is as high as 1/2
p
.
As the pitch of R and B colors in the vertical and horizontal directions is √2
p
, the same as
G, the Nyquist frequency is also 1/2√2
p
.
This is also one of the technologies that, in principle, has an advantage with straight-
forward validity for monochrome image capture, but is quite different for color image
capture by single-chip color systems.
Since many objects in near achromatic color overlap the spectral response of the green color
filter with that of the red and blue filters, decay at this level is infrequent. But a rather com-
plicated signal processing is required as well as a wider overlapping of the spectral response
between colors, which tend to degrade the hue accuracy. Because an interleaved array
fy
1/√2
p
B/W
R
1/2
p
G
1/2/√2
p
GG
B
R
R
R/B
fx
GGG
G
1/2/√2
p
1/√2
p
B
R
B
G
G
B
√2
p
√2
p
(a)
(b)
FIGURE 7.7
(a) Pixel interleaved array with Bayer configuration color filter; (b) Nyquist frequency of each color. (Reprinted
with permission from Kosonocky, W., Yang, G., Ye, C., Kabra, R., Xie, L., Lawrence, J., Mastrocolla, V., Shallcross,
F., and Patel, V.,
Proceedings of the IEEE Solid-State Circuits Conference Digest of Technical Papers
, 11.3, pp. 182-183,
San Francisco, CA, 1996.)
