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FFY-U3-16S2M-DL

 

Auto Algorithm Control

Auto Exposure (AE)

Auto exposure (AE) control is designed to automatically determine the exposure time and gain of the camera so that the resulting image looks as bright as expected. In general, the camera supports various auto exposure features, and these features produce different results in the final image. In addition, the camera allows users to control how fast the exposure and gain get settled.

Note that for AE to work, Exposure Auto and/or Gain Auto must be set to Once or Continuous and ISP must be enabled.

Auto Exposure Features

To enable AE, Exposure Auto and/or Gain Auto must be set to Once or Continuous. AE automatically determines the exposure time and/or gain according to the target image average.

The target image average can be manually or automatically controlled.

For manual control, set Target Grey Value Auto to Continuous and then set the desired image average in Target Grey Value. This value is a percentage of the maximum pixel value.

For automatic control, set Target Grey Value Auto to Off. The target image average is then automatically determined according to user-defined AE modes and other AE features.

By default, AE uses an exposure range of 100 to 15000 µs and/or gain range of 0 to 18 dB and target grey value, but these can be limited.

Exposure Time Lower Limit / Exposure Time Upper Limit - the lower and upper values in microseconds (µs) that the exposure time may reach when exposure is set to Once or Continuous.

Gain Lower Limit / Gain Upper Limit - the lower and upper values in decibels (dB) that the gain may reach when gain is set to Once or Continuous.

Target Grey Value Lower Limit / Target Grey Value Upper Limit - the lower and upper values in percent (%) that the target image average may reach.

Auto Exposure Damping controls how fast the exposure and gain get settled. A small damping value may result in the system being unstable. The range is from 0.0 - 1.0. The default value is 0.5.

If both exposure time and gain are set to Once or Coninuous AE determines which to adjust first by the Auto Exposure Control Priority.

If gain priority is selected, the camera sets the gain to 0 dB, and the exposure is adjusted according to the target grey level. If the maximum exposure is reached before the target grey level is hit, the gain starts to change to meet the target. This mode is used to have the minimum noise.

If exposure priority is selected, the camera sets the exposure to a small value (default is 5 ms). The gain is adjusted according to the target grey level. If maximum gain is reached before the target grey level is hit, the exposure starts to change to meet the target. This mode is used to capture fast motion.

AE Lighting Mode can compensate for strong light sources in front or behind an object. The options are: Backlight, Frontlight, or Normal. The default lighting mode is Normal. Use the Lighting Mode feature to select depending on your conditions.

Backlight Compensation

The backlight compensation mode isused when a strong light is coming from the back of the object. For example, people standing in the shade with the bright sky at the back. A regular auto exposure algorithmmakes the object underexposed in such lighting conditions. Backlight compensation is able to properly expose the object when a strong backlight occurs, regardless of the locations of the object relative to the frame.

Frontlight Compensation

The frontlight compensation mode is used when a strong light is shining in the front of the object while the background is dark. For example, a parking spot that has lights on at night while its surrounding areas are very dark. A regular auto exposure algorithm makes the object overexposed in such lighting conditions. Frontlight compensation is able to properly expose the object when a strong front light and a dark background appear, regardless of the locations of the object relative to the frame.

Summary Table

Name Interface Access Visibility Description
Target Grey Value Auto IEnumeration Beginner This indicates whether the target image grey level is automatically set by the camera or manually set by the user. Note that the target grey level is in the linear domain before gamma correction is applied.
Target Grey Value IFloat RW This is the user-specified target grey level (image mean) to apply to the current image. Note that the target grey level is in the linear domain before gamma correction is applied.
Lighting Mode IEnumeration RW Beginner Selects a lighting mode: Backlight, Frontlight or Normal (default). a. Backlight compensation: used when a strong light is coming from the back of the object. b. Frontlight compensation: used when a strong light is shining in the front of the object while the background is dark. c. Normal lighting: used when the object is not under backlight or frontlight conditions. When normal lighting is selected, metering modes are available.
Exposure Time Lower Limit IFloat RW The smallest exposure time that auto exposure can set.
Exposure Time Upper Limit IFloat RW The largest exposure time that auto exposure can set.
Gain Lower Limit IFloat RW The smallest gain that auto exposure can set.
Gain Upper Limit IFloat RW The largest gain that auto exposure can set.
Target Grey Value Lower Limit IFloat RW The lowest value in percentage that the target mean may reach.
Target Grey Value Upper Limit IFloat RW The highest value in percentage that the target mean may reach.
Auto Exposure Damping IFloat RW Beginner It controls how fast the exposure and gain get settled. If the value is too small, it may cause the system to be unstable. Range is from 0.0 to 1.0. Default = 0.2.
Auto Exposure Control Priority IEnumeration RW Beginner Selects whether to adjust gain or exposure first. When gain priority is selected, the camera fixes the gain to 0 dB, and the exposure is adjusted according to the target grey level. If the maximum exposure is reached before the target grey level is hit, the gain starts to change to meet the target. This mode is used to have the minimum noise. When exposure priority is selected, the camera sets the exposure to a small value (default is 5 ms). The gain is adjusted according to the target grey level. If maximum gain is reached before the target grey level is hit, the exposure starts to change to meet the target. This mode is used to capture fast motion.

Auto Algorithm Control Features


Target Grey Value Auto

This indicates whether the target image grey level is automatically set by the camera or manually set by the user. Note that the target grey level is in the linear domain before gamma correction is applied.

Property Value
Name AutoExposureTargetGreyValueAuto
Interface IEnumeration
Access
Visibility Beginner

Enumeration Values
Off
Continuous

Target Grey Value

This is the user-specified target grey level (image mean) to apply to the current image. Note that the target grey level is in the linear domain before gamma correction is applied.

Property Value
Name AutoExposureTargetGreyValue
Interface IFloat
Access RW
Unit %
Visibility

Lighting Mode

Selects a lighting mode: Backlight, Frontlight or Normal (default). a. Backlight compensation: used when a strong light is coming from the back of the object. b. Frontlight compensation: used when a strong light is shining in the front of the object while the background is dark. c. Normal lighting: used when the object is not under backlight or frontlight conditions. When normal lighting is selected, metering modes are available.

Property Value
Name AutoExposureLightingMode
Interface IEnumeration
Access RW
Visibility Beginner

Enumeration Values
AutoDetect
Backlight
Frontlight
Normal

Exposure Time Lower Limit

The smallest exposure time that auto exposure can set.

Property Value
Name AutoExposureExposureTimeLowerLimit
Interface IFloat
Access RW
Unit us
Visibility

Exposure Time Upper Limit

The largest exposure time that auto exposure can set.

Property Value
Name AutoExposureExposureTimeUpperLimit
Interface IFloat
Access RW
Unit us
Visibility

Gain Lower Limit

The smallest gain that auto exposure can set.

Property Value
Name AutoExposureGainLowerLimit
Interface IFloat
Access RW
Unit dB
Visibility

Gain Upper Limit

The largest gain that auto exposure can set.

Property Value
Name AutoExposureGainUpperLimit
Interface IFloat
Access RW
Unit dB
Visibility

Target Grey Value Lower Limit

The lowest value in percentage that the target mean may reach.

Property Value
Name AutoExposureGreyValueLowerLimit
Interface IFloat
Access RW
Unit %
Visibility

Target Grey Value Upper Limit

The highest value in percentage that the target mean may reach.

Property Value
Name AutoExposureGreyValueUpperLimit
Interface IFloat
Access RW
Unit %
Visibility

Auto Exposure Damping

It controls how fast the exposure and gain get settled. If the value is too small, it may cause the system to be unstable. Range is from 0.0 to 1.0. Default = 0.2.

Property Value
Name AutoExposureControlLoopDamping
Interface IFloat
Access RW
Unit
Visibility Beginner

Auto Exposure Control Priority

Selects whether to adjust gain or exposure first. When gain priority is selected, the camera fixes the gain to 0 dB, and the exposure is adjusted according to the target grey level. If the maximum exposure is reached before the target grey level is hit, the gain starts to change to meet the target. This mode is used to have the minimum noise. When exposure priority is selected, the camera sets the exposure to a small value (default is 5 ms). The gain is adjusted according to the target grey level. If maximum gain is reached before the target grey level is hit, the exposure starts to change to meet the target. This mode is used to capture fast motion.

Property Value
Name AutoExposureControlPriority
Interface IEnumeration
Access RW
Visibility Beginner

Enumeration Values
Gain
ExposureTime

 

5/8/2020
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Firefly® FFY-U3-16S2M-DL
Camera Reference