get portion of one image(400*400) by size of 20*20

[icestar]

Hi,
I wanted to get portion of one image(400*400) by size of 20*20.I have not found any function in IMAQ Vision which can resolve this problem directly.So I used ImageToArray and Array Subset,then ArrayToImage. When I wanted to filter this new image(part of primary image),one Error showed as follow.
Error -1074396154 occurred at IMAQ Convolute
The image is not large enough for the operation.

The filter kernel is 9*9. How can I resolve this problem correctly?

[chilly_charly]

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icestar wrote:...I wanted to get portion of one image(400*400) by size of 20*20.I have not found any function in IMAQ Vision which can resolve this problem directly...

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The IMAQ function that byou are looking for is IMAQ Extract in the Image manipulation subpalette. Do not wire the X and Y duplication steps (unless you want also to change the resolution ...) and adjust the values in the Optional Rectangle input.

[BruceAmmons]

Also make sure you set the border of the image large enough. I think the default is 3, and you will need 4 to process with a 9x9 kernel. I can never remember if you need to set the border correctly on the source or destination image, so I usually just set both. Another option is to change the border size after the Extract command.

Bruce