4.6: Exposure: Auto Exposure (Time Base) Auto Exposure mode automatically adjusts the brightness of the image through exposure and gain control. The limits of gain and exposure can be set. The AE algorithm uses the AE detector window to measure the brightness of the image. If the maximum exposure is reached the camera sets a status bit to indicate the iris be opened. There are two counter modes, a smaller mode for windows up to 1Mega pixel and a larger mode for windows up to 16 Mega pixels. The larger counter can cover the entire active area of the RMV-11002. This function is quite complicated. For help contact dave@illunis.com.
Serial Commands Target Index
Quick FAQ’s: ►The AE algorithm adjusts both exposure and gain to control the image brightness. ►The limits of minimum and maximum gain can be set. This allows for control of noise . ►AE does work in TPE mode, it does not work in TME, TOE or TDE modes. ►AE uses digital gain (analog gain is fixed). ►The exposure limits are set in us * 10 = ms / 100 ►Note: In free run mode (FRM) the max and min exposures are checked and reset to the actual time calculated by the SetFreeRunTime function. So when you set a time, you can read it back to find the actual time used by the AE function.
Command
R/W
Description
R
If Bit# 15 = 1 then AE algorithm is the newer (time based) version. 0x0000 = Disable AE 0x0001 = Enable Fast AE 0x0002 = Enable Slow AE 0x0003 = Enable small AED counter (1mpix) 0x0004 = Enable large AED counter(16mpix) 0x0005 = Enable AED averaging 0x0006 = Disable AED averaging
05
00
04
1d
0x0004 = Mode Register #5 Bit# 15: AE Algorithm type Auto Exposure
1e
AE Set point
R/W
04
1f
AE Hysteresis
R/W
04
20
AE max gain
R/W
Maximum digital gain to use in AE
04
21
AE min gain
R/W
Minimum digital gain to use in AE (should be 0x1000 = 1.0X gain)
04
22
AE max exposure
R/W
maximum exposure time
04 04
23 26
AE min exposure AE detector
R/W R
Minimum exposure time Read by AE algorithm to determine brightness of the image.
04
31
AE detector Average
R
Running average of previous AED’s
04 04
32 33
AE Vsync Count AE exposure denominator
R/W R/W
Set to 3 in FRM, 1 in TPE mode Use ~10 for indoor light Use ~200 for outdoor lighting Smaller is faster, too small is unstable
04
34
AE gain denominator
R/W
Use ~2 for indoor light Use ~20 for outdoor lighting
05
00
05
00
0x0004 = Mode Register #5 Bit# 1: AE Close IRIS Request 0x0004 = Mode Register #5 Bit# 0: AE Open IRIS Request
W
04
RMV Operations Manual Revision
The detector value that the AE attempts to reach (including hysteresis). The set-point is dependent on the AED window size and AED maximum value Added and subtracted from set point to determine a stable area for the AE.
Indicates that the image is too bright for the AE and the IRIS should be closed if possible. Indicates that the image is to dim for the AE and the IRIS should be opened if possible.
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