8.Features
© China Daheng Group, Inc. Beijing Image Vision Technology Branch 68
The expected gray value is set by the user, and it is related to the data bit depth. For 8bit pixel data, the
expected gray value range is 0-255, for 10bit pixel data, the expected gray value range is 0-1023, and for
12bit pixel data, the expected gray value range is 0-4095.
The camera adjusts the gain value within the range [minimum gain value, maximum gain value] which is
set by the user.
The auto gain feature can be used with the auto exposure at the same time, when target grey is changed
from dark to bright, the auto exposure adjust is prior to auto gain adjust. Vice versa, when target grey is
changed from bright to dark, the auto gain adjust is prior to auto exposure adjust.
8.3.4.3. Auto Exposure
The auto exposure can adjust the camera's exposure time automatically, so that the average gray value
in AAROI can achieve to the expected gray value. The auto exposure can be controlled by "Once" and
"Continuous" mode.
When using the "Once" mode, the camera adjusts the image data in the AAROI to the expected gray value
once, then the camera will close the auto exposure feature. When using the "Continuous" mode, the
camera will continuous adjusting the exposure time according to the data of the AAROI, so that the data
in the ROI is kept near to the expected gray level.
The expected gray value is set by the user and it is related to the data bit depth. For 8bit pixel data, the
expected gray value range is 0-255, and for 12bit pixel data, the expected gray value range is 0-4095.
The camera adjusts the exposure time in the range [minimum exposure time, maximum exposure time]
which is set by the user.
The auto exposure feature can be used with the auto gain at the same time, when target grey is changed
from dark to bright, the auto exposure adjust is prior to auto gain adjust. Vice versa, when target grey is
changed from bright to dark, the auto gain adjust is prior to auto exposure adjust.
8.3.5. Auto White Balance
8.3.5.1. Auto White Balance ROI
Auto White Balance feature use the image data from AWBROI to calculate the white balance ratio, and
then balance ratio is used to adjust the components of the image.
ROI is defined in the following way:
AWBROIOffsetX: The offset of the X axis direction.
AWBROIOffsetY: The offset of the Y axis direction.
AWBROIWidth: The width of ROI.
AWBROIHeight: The height of ROI.
Offset is the offset value that relative to the upper left corner of the image. Where the step length of X axis
direction offset and width is 4, the step length of Y axis direction offset and height is 2. The ROI setting
depends on the current image and cannot exceed the current image range. Assuming the current image
width is Width, the image height is Height, then the ROI setting need to meet the following condition 2:
