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Preview Mode to Still Image Capture Sequence
Version 1.1, December 7, 2004
Proprietary to OmniVision Technologies
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9 Preview Mode to Still Image Capture Sequence
The procedure for OV9650 preview mode to still image capture sequence for different resolution
and frame rate is as follows:
1. Preview image
2. Press still image button
3. Read out sensor below register values:
• Gain:
Register GAIN[9:0] {
[7:0] (0x00)}
• Exposure: Register AEC[15:0] {
[9:2] (0x10),
[1:0] (0x04)}
4. Set sensor to still image resolution (just change a few registers that are different to preview)
• Turn off sensor AGC and AEC by setting register
[0] (0x13) to low, respectively
• Calculate and set the gain {
[7:0] (0x00)} and exposure time {
[15:10]
[9:2] (0x10),
[1:0] (0x04)} of the still image from the gain and exposure time of the
preview image
5. Wait for two frames and capture the third frame
6. Set back to preview mode and turn on AGC and AEC
7. Preview image
AEC[15:0] responds to horizontal line period for each bit. Horizontal line period includes an active
pixel period and a horizontal blanking period. It counts both active pixel number and blanking pixel
number. So the line period will be:
•
1520Tp (1280+240) for SXGA
•
800Tp (640+160)
for VGA:
•
400Tp (320+80)
for QVGA
•
400Tp ((160+40)x2) for QQVGA
•
520Tp (352+168)
for CIF
•
260Tp (176+84)
for QCIF
•
260Tp ((88+42)x2)
for QQCIF
where Tp depends on the frame rate.