Fix bug when creating symmetrical GLCM #261
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
To make GLCM symmetrical, the python code performed an inplace addition: `P_glcm += numpy.transpose(P_glcm, (1, 0, 2))`. However, when the matrix exceeds a certain size, this produces buggy behaviour, where for some elements, the calculated value equals `P_glcm += P_glcm + numpy.transpose(P_glcm, (1, 0, 2))`. This is caused by the fact that numpy.transpose returns a *view*, and not a copy of the array. Then, if the additions have to be processed in multiple chunks, the addition will become erroneous. Use `numpy.copy` to get a transposed copy of the GLCM and not just a view of the GLCM.
|
Note: baseline is not affected, as this bug occurred when creating a symmetrical GLCM, whereas the baseline is made using the assymetrical GLCM. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
To make GLCM symmetrical, the python code performed an inplace addition:
P_glcm += numpy.transpose(P_glcm, (1, 0, 2)). However, when the matrix exceeds a certain size, this produces buggy behaviour, where for some elements, the calculated value equalsP_glcm += P_glcm + numpy.transpose(P_glcm, (1, 0, 2)). This is caused by the fact that numpy.transpose returns a view, and not a copy of the array. Then, if the additions have to be processed in multiple chunks, the addition will become erroneous.Use
numpy.copyto get a transposed copy of the GLCM and not just a view of the GLCM.