#211 closed defect (invalid)
psImageConvolve
| Reported by: | Paul Price | Owned by: | |
|---|---|---|---|
| Priority: | normal | Milestone: | |
| Component: | imageops | Version: | unspecified |
| Severity: | normal | Keywords: | |
| Cc: |
Description
When convolving using FFT, the image needs to be padded by the larger of the
size of the image and the size of the kernel in order to prevent wrap-around.
This might be why the tst_psImageConvolve isn't working for the Fourier convolution.
Change History (4)
comment:1 by , 22 years ago
comment:2 by , 22 years ago
| Status: | new → assigned |
|---|
comment:3 by , 22 years ago
| Resolution: | → invalid |
|---|---|
| Status: | assigned → closed |
Will revisit this later in the new release, if required.
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I don't think that is the root of the problem, as I did pad the kernel and image
already (needed them the same size to do the convolution in the Fourier domain
in the first place). I also added a border of 32 pixels around the image as to
better handle the edge condition.
Given the result I get is almost correct, only it is shearing parts of the
kernel to other parts of the image, I suspect it is something to do with the
actual FFT conversion. I dumped the padded kernel and image out to fits and
they looked right to me at first glance. I also duplicated part of my algorithm
in MATLAB with success. I just need some time to look abit deeper, and I didn't
have it at the time given all the other things that I needed to do for release.
-rdd