PatchGenerator does not pad

[mhoibo]

I have noticed that patches generated with fast.PatchGenerator on edge cases are not padded. I have padded them manually, but I was wondering if the generator should do it automatically? paddingValue is set to -1 by default, which I though should mean that the patches get padded?

[smistad]

The PatchGenerator should always pad, even when paddingValue is -1, this only means that it should auto select of the padding is white (255) or black (0). See here: https://github.com/smistad/FAST/blob/master/source/FAST/Algorithms/ImagePatch/PatchGenerator.cpp#L150

If you are observing something else, it must be a bug..

[andreped]

I assume it is this test you mean, @smistad?

@mhoibo is using an artifact of pyFAST==4.6.0, hence, this might have been fixed a while back.

But in @mhoibo case, she is having this problem when she has converted a numpy array to a FAST image and then streamed patches from it. Could there be a reason why this would not work then? She is also using an overlapPercent=0.25, but it seems to be an issue regardless if she performs overlap or not.

I can make a simple gist to see if I can reproduce the issue and share it here.

[smistad]

Okay, I see. When you get patches from an image pyramid it seems to pad, but not when getting patches from a regular image.

[andreped]

import fast
import numpy as np

x = np.zeros((1256, 1010), dtype="float32")
image = fast.Image.createFromArray(x)
patchgen = fast.PatchGenerator.create(256, 256, overlapPercent=0).connect(0, image)
streamer = fast.DataStream(patchgen)
for patch in streamer:
    print(np.asarray(patch).shape)

For most patches, we get (256, 256, 1), but we occationally get patches of smaller size. Hence, padding does not seem to work appropriately in this case.

Just tried to do the same with latest stable release of pyFAST in a new virtual environement. So I believe the issue is coming from using the FAST image converted from a numpy array as input to the PatchGenerator.

[andreped]

Okay, I see. When you get patches from an image pyramid it seems to pad, but not when getting patches from a regular image.

Yes, exactly. It is likely the issue. You can use the example above to test it for yourself.

[smistad]

This should be fixed in latest commit