© 2016 Thorlabs Scientific Imaging
4 Programming (SDK)
121
Notes
1. Changing the image size
When changing the size of the AOI, please make sure that the selected image memory is large
enough. If it isn't, allocate a new image memory (see is_AllocImageMem()).
Changes to the image size affect the value ranges of the frame rate and exposure time. After
executing is_AOI(), calling the following functions is recommended in order to keep the defined
camera settings:
o is_SetFrameRate()
o is_Exposure()
o If you are using the flash function: is_IO()
2. Step widths for AOI definition (position grid)
The available step widths for the position and size of image AOIs depend on the sensor. The
values defining the position and size of an AOI have to be integer multiples of the allowed step
widths.
For details on the AOI grids of the individual camera models, please see Camera and sensor data.
3. AOI in combination with high frame rates
With very small AOI and therefore high frame rate and maximum possible frame rate set, it is
possible that the USB camera transfers in freerun mode only half frame rates. This is a signal for a
camera-internal overload. In this case it is recommended to set the frame rate to maximum of 98 %
.
Multi AOI function of the DCC1240x and DCC3240x models
The sensor of a.m. cameras supports multiple AOIs in one image capture. The AOIs are
transferred together as one image. In this mode you can create 2 or 4 AOIs, which have either the
same X axis or the same Y axis (see also uc480 Viewer: Multi AOI). The sensor is faster in this
mode. It is possible to switch the AOI in the horizontal direction.
Sequence AOI mode for DCC1240x and DCC3240x camera models
A.m. camera models have a special AOI mode. In this mode you can define besides the normal
AOI (AOI 1) up to 3 further AOI on the sensor (see uc480 Viewer: Sequence AOI). When activating
the sequence mode, note that only the following combinations are possible:
1. All additional AOIs are off. AOI 1 is always active.
2. AOI 2 (+ AOI 1)
3. AOI 2 and 3 (+ AOI 1)
4. AOI 2, 3 and 4 (+ AOI 1)
It is not possible to have a combination e.g. of AOI 2 and AOI 4.
The parameters of AOI 2, 3 and 4 are defined by the AOI_SEQUENCE_PARAMS structure. In the version
4.80 binning, subsampling and scaler are not supported.
Input parameters
Sets the position and size of the image by using an object of
the IS_RECT type. Sample 1 for AOI
You can define the start position of the AOI in the memory by
ORing IS_AOI_IMAGE_POS_ABSOLUTE with the X or Y position.
Sample for setting the AOI position
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