ov7620 OmniVision Technologies, Inc, ov7620 Datasheet - Page 41

• Manufacturer Part Number: ov7620
• Description: Single-chip Cmos Vga Color Digital Camera
• Manufacturer: OmniVision Technologies, Inc

OV7620/OV7120 Product Specifications - Rev. 1.2 (7/10/01)
Register 25- rw: AEC Auto Exposure Black Pixel Ratio
Register 26 - rw: Common control F
Bits
Interlace
Progressive Scan
Bits
Default
AEB7-AEB0 - used to calculate the black pixel ratio. OV7620/OV7120 AEC algorithm is count whole field/
Note: AEB<7:0> must combined with register [25] AEW<7:0>. Keep the relation always true: AEW<7:0> +
COMF7 - COMF6: Digital Sharpness threshold selection.
[00] - Difference of neighbor pixel luminance is larger than 8 mV, correction on.
[01] - 16 mV.
[10] - 32 mV.
[11] - 64 mV.
COMF5 - COMF4: Digital Sharpness Magnitude selection.
[01] - Strength is 50% of difference of neighbor pixel luminance.
[10] - 100%.
[11] - 200%.
COMF3 - Reserved
COMF2 - Swap bus MSB/LSB. “1” LSB->Bit7, MSB->Bit0; “0” normal.
COMF1 - “1” A/D Black level calibration enable. Do not use “0”.
COMF0 - “1” Output first 4 line black level for Interlaced Mode and 8 line black level for Progressive Scan
COMF7
1
frame white pixel (its luminance level is higher than a fixed level) and black pixel (its luminance
level is lower than a fixed level) number. When white/black pixel ratio is same as the ratio
defined by registers [25] and [26], image stable. This register is used to define black pixel ratio,
default is 75%, each LSB represent step: Interlaced: 1.3%; Progressive Scan: 0.7%. Change
range is: Interlaced: [01] ~ [4A]; Progressive Scan: [01] ~ [96]. Increase AEB<7:0> will
increase black pixel ratio. For same light condition, the image brightness will decrease if
AEB<7:0> increase.
AEB<7:0> > [4D] for Interlaced; AEW<7:0> + AEB<7:0> > [90].
Mode before valid data output. HREF number will increase 4/8 relatively. “0” no black level out-
put.
AEB7
COMF6
0
1
0
AEB6
COMF5
1
0
1
AEB5
COMF4
0
0
0
AEB4
Preliminary
COMF3
0
0
0
AEB3
COMF2
1
1
0
Company Confidential
OMNIVISION TECHNOLOGIES INC.
AEB2
COMF1
0
0
1
AEB1
COMF0
1
1
0
AEB0
0
0