21.2 mvBlueFOX-[Model]202a (1.3 Mpix [1280 x 1024]) 235
21.2.2.1 Snapshot mode
In snapshot mode, the image acquisition process consists off several sequential phases:
21.2.2.1.1 Trigger
Snapshot mode starts with a trigger. This can be either a hardware or a software signal.
The following trigger modes are available:
See also
For detailed description about the trigger modes (https://www.matrix-vision/manuals/ [mvI←-
MPACT Acquire API])
• C: TCameraTriggerMode
• C++: mvIMPACT::acquire::TCameraTriggerMode
21.2.2.1.2 Erase, exposure and readout
After the trigger pulse, the complete sensor array is erased. This takes some time, so there is a fix delay from about
285 us between the trigger pulse on digital input 0 and the start of exposure of the first line.
The exact time of exposure start of each line (except the first line) depends on the exposure time and the position
of the line. The exposure of a particular line N is finished when line N is ready for readout. Image data is read out
line-by-line and transferred to memory (see: http://www.matrix-vision.com/tl_files/mv11/←-
Glossary/art_rolling_shutter_en.pdf).
Exposure time is adjustable by software and depends on the image width. To calculate the exposure step size you
will need following formula:
LineDelay = 0
PixelClkPeriod = 1
--------
PixelClk
RowTime = ( ImageWidth + 244 + LineDelay )
*
PixelClkPeriod
RowTime = MinExposurTime = ExposureStepSize
Image data is then shifted out line-by-line and transferred to memory.
To calculate the maximum frames per second (FPS
max
) in snapshot mode you will need following formula:
FrameTime = (ImageWidth + 244)
*
((ImageHeight + 16) / PixelClock)
FPS_max = 1
-----------------------------------
FrameTime + ExposureTime
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