fix(gldm): exclude background from the dependence matrix#354
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The MATLAB grey-binning path maps off-ROI background (0) to level 1, so the GLDM zone loop's `pi == 0` guard (which tests the BINNED value) never rejected background pixels inside the bounding box. They were counted both as zones and as dependent neighbours, inflating Nz (154 -> 234 on the canonical ROI) and every count/dependence feature. Skip background by the ORIGINAL intensity (imR / raw cloud value == 0) and require a neighbour to be an ROI pixel before counting it as a dependency, in both the trivial and out-of-core paths. Mirrors the GLCM background fix. Adds tests/python/test_feature_bugs.py::test_gldm_background_not_counted, checking LDE/GLN/DN against the PyRadiomics reference on the canonical ROI.
sameeul
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Jul 1, 2026
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| """Regression / bug-exposure tests for 2D feature defects found during oracle validation | ||
| (2026-06). These exercise the PRODUCTION featurize() path on ROIs *with background* and at | ||
| the DEFAULT settings - the conditions the C++ unit tests miss. | ||
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| This module covers the GLDM background-pollution defect (bug #14b). |
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this comment and the file name need to be updated to reflect the test. Saying it test_feature_bugs.py will become misleading in the long run. Also, do we have an equivalent GTest?
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July 1, 2026 11:49
…guard Address PR PolusAI#354 review: the generic test_feature_bugs.py name/comment would become misleading, and there was no C++ equivalent. - Rename tests/python/test_feature_bugs.py -> test_gldm_bugs.py and scope the docstring to the GLDM background-pollution defect (bug #14b). - Add tests/test_gldm_bugs.h::test_gldm_bug_background_excluded, a GTest on a concave 3x3-ring ROI whose bounding box contains a background hole - the condition the fully-masked test_gldm.h phantoms cannot reproduce. Asserts the exact hand-computed GLDM matrix (Nz=8, GLN=8, DN=4, DNN=0.5, LDE=17); the pre-fix background pollution gave GLN 7.22 / DN 3.67 / LDE 15.22. - Register the new test in test_all.cc.
Drop the _bugs suffix from the GLDM regression guards, renaming
test_gldm_bugs.{h,py} -> test_gldm_oracle.{h,py} to reflect their
origin in the PyRadiomics oracle-validation effort. Updates the
test_all.cc include and the cross-reference comments in both files.
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The MATLAB grey-binning path maps off-ROI background (0) to level 1, so the GLDM zone loop's
pi == 0guard (which tests the BINNED value) never rejected background pixels inside the bounding box. They were counted both as zones and as dependent neighbours, inflating Nz (154 -> 234 on the canonical ROI) and every count/dependence feature.Skip background by the ORIGINAL intensity (imR / raw cloud value == 0) and require a neighbour to be an ROI pixel before counting it as a dependency, in both the trivial and out-of-core paths. Mirrors the GLCM background fix.
Adds tests/python/test_feature_bugs.py::test_gldm_background_not_counted, checking LDE/GLN/DN against the PyRadiomics reference on the canonical ROI.