BORDER_REFLECT vs. BORDER_REFLECT_101

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With BORDER_REFLECT also the outer-most border is reflected (copied), while with BORDER_REFLECT_101, the outer-most border is not part of the border. The difference is so subtle that it only matters if you apply it on small matrices (e.g. you want to build a larger kernel). If you typically use it to enlarge your image for filtering you won't see much difference. However, I probably would prefer BORDER_REFLECT_101 since it is a more natural extension and the border doesn't appear twice.

• cv2.BORDER_REFLECT - Border will be mirror reflection of the border elements, like this : fedcba|abcdefgh|hgfedcb

• cv2.BORDER_REFLECT_101 or cv2.BORDER_DEFAULT - Same as above, but with a slight change in which the outter-most pixels (a or h) are not repeated : gfedcb|abcdefgh|gfedcba