SVS-Vistek SHR 10GigE, Manual

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5.1.10 Shutter modes
CCD and CMOS area cameras consist of pixels, ordered in lines and columns.
All pixel are exposed to light and then read out to camera electronics. There is a
difference of reading out the sensor between global and rolling shutter. Especially
flashing and moving objects might need more attention with rolling shutter. Refer
to specifications to determine whether your camera has global or rolling shutter.
There are 3 modes to operate a camera area sensor:
Global shutter mode
l
Global reset of all pixels
l
All pixels start light integration at the same time
l
All pixels stop integration at same time
l
Readout line by line after exposure of whole frame is completed
Artifacts
l
All pixel show same movement artifacts
l
In case of exposure time too long, all pixels blurred
Use short exposure times for preventing blur artifacts. Image of moving object on
sensor must not move more than half pixel width.
Exposure with flash
Flash strobe at any time and length while exposing. With moving objects, light
pulse has to be short enough to prevent blur artifacts.
Rolling shutter mode
l
Pixel reset line by line
l
Line by line light integration
l
Integration starts with different point of time for each line
l
All lines stop integration at different time
l
Line readout immediately after line exposure
l
Next integration has to wait for finished readout (per line)
l
No external exposure control (expose while trigger signal active)
Limitations
Use short exposure times for preventing blur / deforming artifacts. Image of mov-
ing object on sensor must not move more than half pixel width. In case of moving
objects, exposure movement on sensor has to be shorter than half a pixel for
whole image.
Make sure your light is ON as long any pixel are going to be exposed. Total ima-
ging time is exposure time plus scanning time.
Minimum scan time in most cases is about 1 frame length.
With rolling shutter the whole sensor has to be read out – always. That means
applying ROI will reduce the amount of final data being transmitted out of the cam-
era (and the frame rate might rise, due to the limited bandwidth of the interface).
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