nearest_aligned is not aligned

[awused]

When using nearest_aligned the output is noticeably shifted down and to the right. This affects my models severely and causes noticeable warping in their output.

I used this code in augmentations.py to produce the output images:

if __name__ == '__main__':
    img = cv2.imread('test.png')
    img_A, _ = Scale(img=img, scale=4, algo=997, ds_kernel=None, img_type='cv2')
    cv2.imwrite('output.png', img_A)

original image

Output from nearest_aligned as per the above code:

Output from convert test.png -interpolate Average -filter point -resize 25% magick-nearest.png:

Explicitly sampling the top left corner closely matches the offset from nearest_aligned:
convert test.png -define sample:offset=0%x0% -sample 25% magick-sampled-top-left.png

[victorca25]

Any change in nearest_aligned would go in https://github.com/victorca25/augmennt, but can you test what I commented here:

traiNNer/codes/dataops/augmennt/augmennt/transforms.py

Line 2582 in 12d006f

Note: the default kernel size is set to 21, but 17 works.

For the cases I tested, the images were aligned, but maybe in some cases it needs a larger blur kernel.

[awused]

I've tested it on multiple files, it's not like the input file matters. I first noticed it as warping in the output of my models, which was obviously apparent and corrected after I implemented my own local fix, but my local fix is a hack that can't be merged that only works locally because I don't trigger any other code paths that use sample().

As the code is now it's simply wrong. I cannot guess how you tested it to make it appear correct, but my tests are repeatable at both 2x and 4x.