Fixed multiband blender memory leak 27333 #28085Fixes#27333
This PR fixes a memory leak in MultiBandBlender where memory from pyramid vectors was not being released when prepare() was called multiple times or when the blender object was reused.
Problem:
MultiBandBlender retains hundreds of MB to several GB of memory even after the blender pointer is released. The issue occurs because:
1. The resize() function on std::vector does not release memory when the new size is less than or equal to the current size
2. It only adjusts the size marker while retaining the capacity and existing data
3. When prepare() is called, the pyramid vectors are resized but old data remains allocated
Example from the bug report: Blending 14 images (1920x1080) retained ~200MB after blender.release(). With larger images, several GB could be retained.
Root Cause:
GPU path (lines 254-256): Correctly calls clear() before operations
Non-GPU path (lines 285-298): Missing clear() calls, causing resize() to retain old data
Solution:
Added .clear() calls before .resize() in the non-GPU path to match the GPU path behavior. This ensures:
- Memory from previous blend operations is released in prepare()
- Reusing a blender object doesn't accumulate memory
- Behavior is consistent between GPU and non-GPU code paths
Changes:
modules/stitching/src/blenders.cpp: Added 2 clear() calls (dst_pyr_laplace_.clear() and dst_band_weights_.clear()) before resize() in the non-GPU path
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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 (4.x)
- [x] There is a reference to the original bug report and related work (issue #27333)
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
N/A - This is a memory management fix that doesn't affect algorithm behavior. Existing stitching tests verify correctness.
- [x] The feature is well documented and sample code can be built with the project CMake
The fix maintains existing API behavior, no documentation changes needed
Fix memory leak in pyopencv_to for path-like objects #28047
This PR fixes a memory leak in pyopencv_to when handling path-like objects (e.g., pathlib.Path).
Problem:
PyOS_FSPath() returns a new strong reference, but the code was not calling Py_XDECREF to decrement it, causing a memory leak on every call with path-like arguments.
Solution:
Store the returned reference from PyOS_FSPath() in a separate variable path_obj
Call Py_XDECREF(path_obj) on all function exit paths (both success and error paths)
This ensures proper reference counting without changing the function's behavior
Testing:
The leak can be reproduced using the steps in issue #28046 with Python built with --with-address-sanitizer. This fix ensures the reference is properly released.
Fixes#28046
Pull Request Readiness Checklist
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✓ I agree to contribute to the project under Apache 2 License.
✓ 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
✓ The PR is proposed to the proper branch (4.x)
✓ There is a reference to the original bug report and related work (#28046)
NA There is accuracy test, performance test and test data in opencv_extra repository, if applicable
Patch to opencv_extra has the same branch name.
✓ The feature is well documented and sample code can be built with the project CMake
Correct minAreaRect angle to be in range [-90, 0) #28051
### Pull Request Readiness Checklist
Box angle range over all imgproc tests is in interval `[-90, -0.0581199]`
resolves https://github.com/opencv/opencv/issues/27667
resolves https://github.com/opencv/opencv/issues/19472
resolves https://github.com/opencv/opencv/issues/24436
See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
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- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake
imgcodecs: Fix IMWRITE_AVIF_DEPTH typo and update AVIF details on imwrite() #28063
Close https://github.com/opencv/opencv/issues/28062
- Corrected the documentation for `IMWRITE_AVIF_DEPTH`.
- Added descriptions for the new AVIF encoder parameters in `imwrite()` documentation.
### Pull Request Readiness Checklist
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Fixes issue with libavif >= 1.3.0 where subsampling with identity matrix
coefficients is invalid. Aligns OpenCV AVIF writer with updated libavif
conformance rules.
Add optional template mask for findTransformECC #27952
Supersedes #22997
**Summary**
Add optional template mask support to findTransformECC so that only pixels valid in both the template and the image are used in ECC. Backward compatibility is preserved (existing signatures unchanged; one new overload adds templateMask).
**Motivation**
- Real-world frames often contain moving foreground artifacts (e.g., a football over a static field). Masking the object in one frame only is insufficient because its position changes independently of the background. Since we don’t know the warp a priori, we can’t back-project a single mask across frames. The correct approach is to supply both masks and take their intersection.
- Templates may include uninformative/low-texture or noisy regions, or partial overlaps with other objects. Excluding such regions from the alignment improves robustness and convergence.
This PR completes and replaces https://github.com/opencv/opencv/pull/22997
### Pull Request Readiness Checklist
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- [ ] The PR is proposed to the proper branch
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Patch to opencv_extra has the same branch name.
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Handle near-zero convexity in convexHull #28043
### Pull Request Readiness Checklist
resolves https://github.com/opencv/opencv/issues/21482
closes https://github.com/opencv/opencv/issues/14401
Also skip a code that determines orientation inside rotatingCalipers and rely on the order after convexHull
See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
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- [x] The PR is proposed to the proper branch
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Patch to opencv_extra has the same branch name.
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Undistort points convergence #27993
I have looked into the `undistortPoints()` problem of issue #27916 and have found a solution. The problem is, as @Linhuihang has correctly pointed out, that the fixed-point iterations do not converge. Here are the functions which are optimized for the undistortion problem:
$$
\begin{aligned}
r^2 &= x'^2 + y'^2 \\
f_1(x') &= \frac{1 + k_4 r^2 + k_5 r^4 + k_6 r^6}{1 + k_1 r^2 + k_2 r^4 + k_3 r^6} (x'' - 2p_1 x' y' - p_2(r^2 + 2 x'^2) - s_1 r^2 + s_2 r^4) = x' \\
f_2(y') &= \frac{1 + k_4 r^2 + k_5 r^4 + k_6 r^6}{1 + k_1 r^2 + k_2 r^4 + k_3 r^6} (y'' - p_1 (r^2 + 2 y'^2) - 2 p_2 x' y' - s_3 r^2 - s_4 r^4) = y'
\end{aligned}
$$
where $x', y'$ are the undistorted points we want to compute and and $x'', y''$ are the given distorted points. This problem is solved using fixed-point iterations like
$$
x'_{k+1} = f_1(x'_k),\quad
y'_{k+1} = f_2(y'_k)
$$
I guess the issue here is that the distortion function does not necessarily satisfy the [Banach fixed-point theorem](https://en.wikipedia.org/wiki/Banach_fixed-point_theorem), i.e. the slope of the function can be too large. This can be seen in @Linhuihang's comment https://github.com/opencv/opencv/issues/27916#issuecomment-3417883642 - the point series jumps around and doesn't converge.
A common solution is to instead do damped fixed-point iterations, so that the updates are "more smooth".
$$
x'_{k+1} = (1 - \alpha) x'_k + \alpha f_1(x'_k),\quad
y'_{k+1} = (1 - \alpha) y'_k + \alpha f_2(y'_k)
$$
I have implemented a simple logic which starts with $\alpha = 1$ (so just like it is now) and reduces $\alpha$ whenever the optimization error would increase. This seems reasonable to me: the initial logic is to do normal fixed-point iterations and to gradually become "more damped" when we notice that we don't converge. Perhaps there is a better way to ensure convergence, but this is the most straightforward modification to the current code that I have found.
This problem is not due to the $\tau_x, \tau_y$ parameters; it also occurs when they are zero. In fact, the fixed-point iterations are done when the tilt correction of $\tau_x, \tau_y$ has already been applied. I have added a test to reproduce the problem. This PR fixes#27916.
### Pull Request Readiness Checklist
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Patch to opencv_extra has the same branch name.
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make cuda::GpuMatND compatible with InputArray/OutputArray #23913
continuation of [PR#19259](https://github.com/opencv/opencv/pull/19259)
Make cuda::GpuMatND wrappable in InputArray/OutputArray
The goal for now is just wrapping, some functions are not supported (InputArray::size(), InputArray::convertTo(), InputArray::assign()...)
No new feature for cuda::GpuMatND
- [X] I agree to contribute to the project under Apache 2 License.
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core: add copyAt() for ROI operation #27318
Close https://github.com/opencv/opencv/issues/27320
Close https://github.com/opencv/opencv/issues/27298
### Pull Request Readiness Checklist
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Patch to opencv_extra has the same branch name.
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Optimize audio buffer duration calculation in MSMF capture. Fixes#27969#28017
### Description
Cache the repeated calculation of `(bit_per_sample/8)*nChannels` in a local variable to avoid redundant computations in `grabFrame()` and `configureAudioFrame()` functions.
### Changes
- Added `bytesPerSample` local variable in both functions
- Replaced 6 repeated calculations with the cached variable
- Improves performance in frequently called audio processing code
Fixes#27969
Added BitShift option to CLAHE #28014
Briefly, this PR is the fix of https://github.com/opencv/opencv/issues/28002
### Pull Request Readiness Checklist
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docs(py): add pip-based install tutorial #27943
- New tutorial: `doc/tutorials/py_tutorials/py_setup/py_pip_install/py_pip_install.markdown` with anchor `{#tutorial_py_pip_install}`.
- Python setup TOC updated to include the new page near the top.
- Windows/Ubuntu/Fedora pages: added **Quick start (pip)** callout
- Expanded troubleshooting in the pip tutorial (env mismatch, headless GUI notes, wheel mismatches, Raspberry Pi/ARM guidance).
This aligns with the issue request to make `pip install opencv-python` the default path for Python newcomers and reduce confusion from legacy content.
Fixes#24360
### Pull Request Readiness Checklist
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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
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Building OpenCV with oneAPI #28003
### Pull Request Readiness Checklist
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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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Dmitry Kurtaev
Alexander Smorkalov
Ghazi-raad
Alexander Smorkalov
Anshu
Kumataro
Akash A
Alessandro de Oliveira Faria (A.K.A. CABELO)
Dmytro Dadyka
Adrian Kretz
Pierre Chatelier
JayPol999
Vincent Rabaud
Stefania Hergane
harunresit
satyam yadav
omaraziz255
Benjamin Buch