Review of Camera Performance and Features
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41
Using Area of Interest (AOIs)
Reduce Image Data & Enhance Performance
See the section Image Format Control Category in Appendix A for GenICam features associated
with this section and how to use them.
Relevant Features:
If the camera’s field of view includes areas that are not needed for inspection (also refer to the
description in the Flat Field Calibration Region of Interest), then the user may want to ignore this
superfluous image data. Eliminating unwanted image data
that is present in the camera’s field of
view reduces the amount of information the host computer needs to process. It may also result in
an increase to the maximum allowable line rate when using 12 bit output data.
The camera can accommodate up to four Areas of Interest (AOI). Image data outside the AOI are
discarded. Each AOI is user selected and its pixel boundaries defined. The camera will assemble all
individual AOI’s into one contiguous image line with a width equal to the sum of the individual
AOI(‘
s). The frame grabber will need to be adjusted to accommodate the smaller overall image
width. As the host computer defined the size of each individual AOI’s, it will be able to extract and
process each individual AOI from the one larger image.
Steps to Setup Area of Interest
1.
Plan your AOI's.
2.
Stop acquisition.
3.
Set the number of AOI's.
4.
Select the first AOI and set the offset and width.
5.
If the other AOI's are large you may need to select them first and reduce their widths.
6.
Repeat for each AOI in turn.
7.
Start acquisition.
Rules for Setting Areas of Interest
•
The rules are dictated by how image data is organized for transmission over the available
CLHS data lanes.
•
The camera / XML will enforce these rules, truncating entered values where necessary.
1.
Acquisition must be stopped to change the AOI configuration.
2.
1-4 AOI's can be selected.
3.
Minimum width is 96 pixels per AOI.
a.
Minimum total of all AOI widths summed together must be at least 1,024.
4.
Maximum width of all AOI widths summed together must be no more than = 16,384.
a.
There can be maximum 8k bytes per CLHS lane.
5.
AOI width step size is 32 pixels.
6.
The offset of each AOI may be 0 to (16,384
–
96 = 16,288).
a.
Therefore overlapping AOI's are allowed.
7.
Offset and width for individual AOI's will "push" one another.
a.
E.g. if AOI has offset 0, width 16,384, and the offset is changed to 4096, then the
width will be "pushed" to 12,288.
b.
AOI's only affect one another by limiting the maximum width.
8.
AOI's are concatenated together in numerical order and sent to the frame grabber starting
at column zero. If the AOI count is reduced to less than the current AOI count, the AOI
selector will be changed to the largest of the new AOI count available.
