8.Features
© 2023 China Daheng Group, Inc. Beijing Image Vision Technology Branch 109
8.2.9.
Overlapping Exposure and Non-overlapping Exposure
There are two stages in image acquisition of the MERCURY2 USB3 Vision camera: exposure and readout.
Once the camera is triggered, it begins to integrate and when the integration is over, the image data will
be read out immediately.
The MERCURY2 USB3 Vision camera supports two exposure modes: overlapping exposure and non-
overlapping exposure. The user cannot assign the overlapping exposure or non-overlapping exposure
directly, it depends on the frequency of trigger signal and the exposure time. The two exposure mode are
described as below.
Non-overlapping exposure
In non-overlapping exposure mode, after the exposure and readout of the current frame are completed,
then the next frame will expose and read out. As shown in the Figure 8-22, the N
th
frame is read out, after
a period of time, the N+1
th
frame to be exposed.
The formula of non-overlapping exposure frame period:
non-overlapping exposure frame period > exposure time + readout time
Sensor
Exposure
Time
Non-overlaping
Non-overlaping
Frame N
Frame N+1
Frame N+2
Frame N
Frame N+1
Sensor
Readout
Blank
Blank
Figure 8-22 The exposure sequence diagram in non-overlapping exposure mode
Trigger acquisition mode
If the interval between two triggers is greater than the sum of the exposure time and readout time,
overlapping exposure will not occur, as shown in Figure 8-23.
Sensor
Exposure
Time
Frame N
Frame N+1
Frame N+2
Frame N
Frame N+1
Sensor
Readout
Trigger
Trigger
Trigger
Figure 8-23 The trigger acquisition exposure sequence diagram in non-overlapping exposure mode