Datasheet

PDF: 09005aef8202ec2e/Source: 09005aef8202ebf7 Micron Technology, Inc., reserves the right to change products or specifications without notice.
MT9D111__7_REV5.fm - Rev. B 2/06 EN
174 ©2004 Micron Technology, Inc. All rights reserved.
MT9D111 - 1/3.2-Inch 2-Megapixel SOC Digital Image Sensor
General Purpose I/O
Micron Confidential and Proprietary
Figure 47: Computation of Sharpness Scores and Luminance Average for
an AF Window
Figure 47 shows the computation of sharpness scores and average luminance in an AF
window. Coefficients of the two AF filters are programmable. The filters shown here as
an example yield convolution results F
1
= 2Y
2
- 8Y
3
+ 12Y
4
- 8Y
5
+ 2Y
6
and F
2
= 2Y
0
- 8Y
2
+
12Y
4
- 8Y
6
+ 2Y
8
.
The symmetry constraint placed on the AF filters reduces the number of coefficient val-
ues needed to define them. Symmetric 8- or 9-coefficient filters are defined by specifying
4 or 5 coefficient values, respectively. Only 4 coefficients are needed to define an 8- or 9-
coefficient antisymmetric filter. Examples of AF filters that can be programmed into
MT9D111 are given in Table 41. To program the first AF filter, one must write its parame-
ters to IFP registers R75:2 and R76:2. The parameters of the second AF filter must be
written to IFP registers R85:2 and R86:2.
.
Table 41: Examples of AF Filters that can be Programmed into the MT9D111
Filter Parameters Programmed into Registers
Filter
Filter
Size
Filter
Symmetry
Filter Coefficients Filter
Weight
C0 C1 C2 C3 C4
8 symmetric n/a 6 -7 2 0 1 [0 2 -7 6 6 -7 2 0]
8 antisymmetric n/a 1 0 0 0 1/4 [0 0 0 -1/4 1/4 0 0 0]
9 symmetric 6 0 -4 0 1 2 [2 0 -8 0 12 0 -8 0 2]
9 antisymmetric 0 15 5 0 0 1/8 [0 0 -5/8 -15/8 0 15/8 5/8 0 0]
ROW R+1
0 0 2 -8 12 -8 2 0 0
Y
0
Y
1
Y
2
Y
3
Y
4
Y
5
Y
6
Y
7
Y
8
Y
9
…
ROW R-1
AF FILTER 1:
AF FILTER 2:
PIXEL Y DATA:
IFP REGISTERS
|F1|
|F2|
AF WINDOW
ROW R
ROW R-2
ROW R+2
2 0 -8 0 12 0 -8 0 2
Pixels in
Window
S
1
= |F1|
Pixels in
Window
<Y>
S
2
= |F2|
Pixels in
Window
N Pixels in
Window
Y