Table of Contents   MOBOTIX Online Help

Exposure Settings

Open the Exposure Settings dialog to adjust the exposure settings of the camera and to optimize it for the current lighting condition. The MOBOTIX camera is equipped with several automatic features so that the best possible images can be created under all weather and lighting conditions. Normally, only extreme conditions call for manual modifications of the exposure settings.

Notes:


Description of Parameters

Linked Image Control

This mode uses the same exposure values and internal image correction settings for both sensors. This ensures that the images from both sensors look as similar as possible.

Note: This parameter is only available for models with identical image sensors.

Automatic Contrast The automatic contrast should always be activated in order to create high-contrast images under all lighting conditions.
Off Deactivates contrast enhancement.
Standard The camera enhances image contrast evenly using the whole image area.
Extended The camera enhances image contrast by displaying dark areas brighter without loosing details in the areas that are already illuminated well (the camera tries to amplify these areas also).
Since the contrast enhancement is not applied evenly, the images may get a somewhat unnatural touch.
Aggressive Works similar to Extended, but enhancement is not restricted. This mode may produce images that look unnatural.
Brightness

Changing the Brightness parameter will adjust the entire image area.

Notes:

  • Configure the Exposure Windows first (see below). This is usually sufficient to achieve good image exposure control.
  • If setting the exposure windows alone does not produce satisfying results, you may want to use the Brightness parameter for fine tuning.
  • Selecting high values for this parameter that are too high may lead to overexposure of bright image areas.
Backlight Correction

This parameter also is used for adjusting the brightness of an image. However, it only affects the darker portions of an image.

Notes:

  • Start by configuring the Exposure Mode and the Exposure Windows (see below). This is usually sufficient to achieve good image exposure control.
  • If setting the exposure windows alone does not produce satisfying results, you may want to use the Backlight Correction parameter for fine tuning.
Exposure Mode

Full Image: The full image of the sensor (i.e. the 1x Zoom, no lens correction on cameras which have this feature) is used to determine the proper exposure. The following parameters for exposure windows, exposure weighting and white balance weighting are used to set the appearance of the image.
This is the preferred mode when using Full Image Recording in the background. This mode guarantees that the recording channel always keeps its exposure.

Visible Image Area: This mode optimizes exposure control for the visible image section. Other parameters are not used, i.e. the settings of the exposure windows, exposure weighting and white balance weighting parameters are ignored.

Note: If the camera uses Full Image Recording, this setting could render the recorded images unusable (e.g. when zooming into very dark or very bright areas of the image, the rest of the image will be overexposed or underexposed, respectively).

Exposure Window

Exposure windows are defined image areas that are used for exposure and color adjustment. To facilitate exposure window positioning, you can select from a number of pre-defined exposure windows.

Notes:

  • This setting is only relevant in the Full Image Area exposure mode.
  • All exposure window dimensions refer to the entire image sensor.
  • If the camera image has been mirrored or rotated, the positioning of the predefined exposure windows and the coordinate system of the custom windows changes accordingly.
  • If your camera is a dual lens model, you can define different exposure windows for each lens.
  • You may also use the exposure windows to perform the automatic White Balance adjustment.

Predefined exposure windows:

Custom Windows

This value allows using custom exposure windows. You can define such a window by creating a selection rectangle in the live image ([Shift]-click, click into the image, then click on Add Rectangle), by using the Exposure Control Quick Control or manually by editing the exposure window definitions in the Custom Windows text field.

Every line in the definition box that does not begin with a hash sign (#, comment - can be used to deactivate exposure windows) defines one exposure window.

Exposure windows can be defined either as rectangles or as polygons.

Rectangle syntax:
[#]image sensor, horizontal position, vertical position, with, height[, in/out]
(optional parameters have brackets)
Example of the pre-defined Quarter window in rectangle syntax:

0,224,168,832,624,in

Polygon syntax:
[#]image sensor, poly=<hor. coordinate>x<vert. coordinate>{/<hor. coordinate>x<vert. coordinate>}[, in/out]
(optional parameters have square brackets, parameters that can be used as often as needed have curly brackets)
Example of the pre-defined Quarter window in polygon syntax:

0,poly=224x168/224x791/1055x791/1055x168,in

Parameter

# Introduces a comment line. Can be used to temporarily deactivate an exposure window definition without having to delete it.
Image Sensor 0 = right camera lens
1 = left camera lens
Horizontal position Position of the left exposure window border measured from the left edge of the visible image in pixels (based on a MEGA image 1280x960).
Vertical position Position of the lower window border measured from the lower edge of the visible image in pixels (based on a MEGA image 1280x960).
Width Width of the exposure window in pixels (based on a MEGA image 1280x960).
Height Height of the exposure window in pixels (based on a MEGA image 1280x960).
Horizontal coordinate Position of the left exposure window border measured horizontally from the left edge of the visible image to the polygon corner in pixels (based on a MEGA image 1280x960).
Vertical coordinate Position of the left exposure window border measured vertically from the bottom edge of the visible image to the polygon corner in pixels (based on a MEGA image 1280x960).
in

The current exposure window defines an area that is used for exposure control (default).

If Show Windows is set to On, the exposure windows will be displayed with a green frame.

out

The current exposure window defines an area that is excluded from exposure control.

If Show Windows is set to On, the exposure windows will be displayed with a red frame.

Exclusion windows are used to remove specific areas within "regular" exposure windows from exposure control.

Full Image Uses the complete image area for exposure control.
Quarter An exposure window at the image center that covers a quarter of the viewable image area.
Center One exposure window at the image center.
Spot One small exposure window at the image center.
Top One horizontal exposure window at the top of the image.
Middle One horizontal exposure window at the image center.
Bottom One horizontal exposure window at the bottom of the image.
Right One vertical exposure window at the right border of the image.
Vertical One vertical exposure window at the image center.
Left One vertical exposure window at the left border of the image.
Right & Left Two vertical exposure windows at the left and right borders of the image.
Exposure Weighting

Using this parameter, you can define how much the exposure windows are to be considered for exposure control—relative to the rest of the image.
Values: Total .. 0% .. 100%

The factory default setting is 100% which means that only the exposure windows are used for exposure control.

White Bal. Weight

Using this parameter, you can define how much the exposure windows are to be considered for white balancing—relative to the rest of the image.
Values: Total .. 0% .. 100%

The factory default setting is Total which means that the entire image is used for white balance.

Show Window

On: Displays the defined exposure window(s) with green frames in the image. Exclusion windows are shown with a red frame.
The Histogram option shows additional parameters of specific image processing features in the image.

Average Brightness

This parameter of exposure control (default is 40%) specifies the average brightness of the image pixels considered for exposure control (→ exposure windows) that the camera tries to reach; it is thus the target value for the finished image's brightness. In order to reach this value, the camera first tries to change the exposure time within the limits set by the minimum and maximum exposure time and adjusts the hardware amplification within the internally defined limits.

Minimum Average Brightness

If the brightness continues to decrease, the camera extends the exposure time and increases the hardware amplification to maintain the specified average brightness, until the maximum exposure time has been reached.

If it still gets darker, the image brightness drops below the value of the average brightness and approaches the value of the minimum average brightness. If the image brightness drops below this value, the camera will activate the software amplification to maintain the minimum average brightness for as longs as possible.

When setting this parameter, the following rules apply:

  • A lower value produces images with higher quality, which may become darker and thus constitute a more natural reflection of reality. The default value of 20% results in a largely lifelike behavior.
  • A higher value increases the brightness of the images, but it can produce images with lower quality due to increased image noise.
Night Improvement

This feature improves the contrast of dark images.

Note: Activating this parameter may result in an increase of image noise.

Exposure Program

These parameters influence the balance between an exposure time that is as short as possible and hardware amplification that is as low as possible. The objective is to reach a fair compromise between clear images of moving objects (short exposure time, high amplification) and as little image noise as possible (long exposure time, low amplification).

When using the camera in a web application, a positive value would create images with little amplification (i.e. little image noise); moving objects would be displayed in a blurred manner. On the other hand, a security application would require a negative value to show moving objects as clearly as possible, even if this would mean higher image noise.

Max. Exposure Time Set the maximum exposure time in seconds.
Min. Exposure Time Set the minimum exposure time in seconds.
Frequency of Power Supply This parameter sets the camera to the power supply frequency of the respective country to prevent interference by artificial light.
The factory default setting for Europe is 50 Hz. For Canada, the U.S.A. and Japan, set the power supply frequency to 60 Hz. If the camera is used in daylight conditions (rather than artificial illumination), you can also use the No artificial light setting.

Storing the Configuration

Click on the Set button to activate your settings and to save them until the next reboot of the camera.

Click on the Factory button to load the factory defaults for this dialog (this button may not be present in all dialogs).

Click on the Restore button to undo your most recent changes that have not been stored in the camera permanently.

Click on the Close button to close the dialog. While closing the dialog, the system checks the entire configuration for changes. If changes are detected, you will be asked if you would like to store the entire configuration permanently.

cn, de, en, es, fr, it, jp, ru

© 2001-2017 MOBOTIX AG, Germany · http://www.mobotix.com/