imgproc: avoid NaN in masked TM_CCOEFF_NORMED for constant templates - #29071
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- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
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Patch to opencv_extra has the same branch name.
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### Summary
Fixes#23257.
This patch handles a degenerate masked `TM_CCOEFF_NORMED` case in `matchTemplate()`. When the template is constant over the effective mask area, the template norm can become zero or NaN, which may propagate NaN/Inf values into the result. The masked path now returns all ones for this case, matching the existing behavior of the unmasked `TM_CCOEFF_NORMED` implementation for constant templates.
### Tests
- `cmake --build build_project4 --target opencv_test_imgproc -j4`
- `./build_project4/bin/opencv_test_imgproc '--gtest_filter=Imgproc_MatchTemplateWithMask.regression_23257_constant_template'`
- `./build_project4/bin/opencv_test_imgproc '--gtest_filter=*MatchTemplate*'`
The MatchTemplate-related test filter ran 147 tests successfully.
* imgproc: templmatch: Add support for mask for all methods
Add support for masked template matching. Fix/scrub old implementation
for masked matching, as it did partly not even really do a meaningful
masking, and only supported limited template matching methods.
Add documentation including formulas for masked matching.
* imgproc: test: Add tests for masked template matching
Test accuracy by comparing to naive implementation for one point.
Test compatibility/correctness by comparing results without mask and
with all ones mask.
All tests are done for all methods, all supported depths, and for 1 and
3 channels.
* imgproc: test: templmatch: Add test for crossCorr
Add a test for the crossCorr function in templmatch.cpp. crossCorr() had
to be added to exported functions to be testable.
This test can maybe help to identify the problem with template matching
on MacOSX.
* fix: Fixed wrong evaluations of the MatExpr on Clang
* fix: removed crossCorr from public interface.
If it should be exported, it should be done as separate PR.
Co-authored-by: Vadim Levin <vadim.levin@xperience.ai>
