imgproc: fix heap-buffer-overflow in stackBlur #28233#28250
### Summary
Fixes a heap-buffer-overflow in `cv::stackBlur` when the kernel size is larger than the image dimensions
### Changes
* Added input validation to clamp the kernel size to the image dimensions.
* Added a regression test (`regression_28233`) covering 1x1 and small image cases.
Fixes#28233
core: fix solveCubic numerical instability via coefficient normalization (fixes#27748) #28117
Summary
This PR fixes numerical instability in `cv::solveCubic` when the leading coefficient `a` is non-zero but extremely small relative to other coefficients (Issue #27748).
It introduces a **normalization step** that scales all coefficients by their maximum magnitude before solving. This ensures robust detection of when the equation should degenerate to a quadratic solver, without breaking valid cubic equations that happen to have small coefficients (e.g., scaled by 1e-9).
The Problem (Issue #27748)
The previous implementation checked `if (a == 0)` to decide whether to use the cubic or quadratic formula.
- When `a` is extremely small (e.g., 1e-17) but not exactly zero, and other coefficients are normal (e.g., 5.0), the standard cubic formula suffers from catastrophic cancellation and overflow, producing incorrect roots (e.g., 1e14).
The Fix
1. Normalization: The solver now finds `max_coeff = max(|a|, |b|, |c|, |d|)` and scales all coefficients by `1.0 / max_coeff`.
2. Relative Threshold: It then checks `if (abs(a) < epsilon)` on the *normalized* coefficients.
Why this is better than previous attempts
In a previous attempt (PR #28057), a simple absolute check `abs(a) < epsilon` was proposed. That approach was rejected because it failed for scaled equations.
Fixes#27748
Added randomNormalLike layer to 4.x branch #28164
OpenCV Extra: https://github.com/opencv/opencv_extra/pull/1297
Backport of https://github.com/opencv/opencv/pull/28110 to 4.x
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Stateless HAL for filters and morphology. #28208
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[video] Add setCoarsestScale to DISOpticalFlow (Fixes#25068) #28217
### Description
This PR addresses issue #25068 regarding the number of scales in `DISOpticalFlow`.
Currently, `DISOpticalFlow` automatically computes the `coarsest_scale` based on the image size. While generally effective, this behavior can cause errors in specific use cases (e.g., mechanics/speckle pattern analysis) where high pyramid levels degrade quality.
This change introduces a manual override:
- Added `setCoarsestScale(int val)` and `getCoarsestScale()` to the public API.
- Updated `DISOpticalFlowImpl::calc` and `ocl_calc` to use the user-defined scale if set.
- Preserved the existing "automatic" behavior as the default (when set to -1).
### Changes
- **`modules/video/include/opencv2/video/tracking.hpp`**: Added virtual method declarations.
- **`modules/video/src/dis_flow.cpp`**: Implemented `set/getCoarsestScale` in `DISOpticalFlowImpl` and updated calculation logic.
- **`modules/video/test/test_OF_accuracy.cpp`**: Added `DenseOpticalFlow_DIS.ManualCoarsestScale` regression test.
Fixes#25068
Keep convexHull output indices monotone if possible #28163
### Pull Request Readiness Checklist
resolves https://github.com/opencv/opencv/issues/24907 ?
resolves https://github.com/opencv/opencv/issues/4954
See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
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Replaces wasteful temporary object construction with in-place construction using emplace_back. Covers hot paths in objdetect, imgproc, and stitching modules.
dnn(tflite): add support for MAXIMUM layer #28171Fixes#26433
This PR adds support for the `MAXIMUM` layer in the TFLite importer.
It maps the TFLite `MAXIMUM` opcode to the existing OpenCV Element-wise `Max` operation.
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Fix regex escape warning in _coverage.py by using raw string #2819
while i am running '_coverage.py' I noticed there is a syntax warning:"\." It is an invalid escape sequence
The regex was written as a normal string with '\.' which is not valid escape in string literals and give problems and error in a new python versions.
To fix this switch to raw string(r'cv2?\.\w+') which can passes the backslashes directly to the regex engine. This removes the warning and keeps the code and pattern working properly.
This is a small fix but important for future compatibilities.
core: suppress LAPACK deprecation warnings on macOS #28203
### Description
On macOS (Apple Silicon) with newer Xcode/Clang, the CLAPACK interface is deprecated.
Compiling `hal_internal.cpp` triggers multiple warnings like:
`warning: 'sgesv_' is deprecated: first deprecated in macOS 13.3 - The CLAPACK interface is deprecated. [-Wdeprecated-declarations]`
Since migrating to the new Accelerate interface (Apple's recommended fix) requires significant changes to the HAL implementation and breaks the build if headers are mismatched, this PR takes the pragmatic approach. It suppresses the `-Wdeprecated-declarations` warning for this specific file using Clang pragmas to clean up the build output.
### Verification
- [x] Verified build is silent on macOS (M3).
- [x] Verified pragmas are correctly scoped within `HAVE_LAPACK` to prevent scope mismatch on non-LAPACK builds.
### Pull Request Readiness Checklist
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imgcodecs(avif): add safety checks for AVIF decoder and encoder #28200
Add defensive checks to prevent potential null dereference in AVIF decoder and encoder paths when handling malformed input or allocation failures.
### Pull Request Readiness Checklist
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Fixed issues identified by PVS Studio #28185
Partially fixes https://github.com/opencv/opencv/issues/28167
Paper: https://pvs-studio.com/en/blog/posts/cpp/1321/
Closed items: N2, N4, N5, N6, N7, N8, N10, N11, N13, N14.
To be continued...
### Pull Request Readiness Checklist
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Emscripten 3.1.71+ introduced ClassHandle.clone() which performs a shallow copy.
This shadowed the original OpenCV clone() method which was intended for deep copying.
This patch:
1. Hooks into onRuntimeInitialized in helpers.js
2. Overrides cv.Mat.prototype.clone to point to mat_clone (deep copy)
3. Updates JS tests to use clone() to verify the fix
Introduce option to generate Java code with finalize() or Cleaners interface #28159
Closes https://github.com/opencv/opencv/issues/22260
Replaces https://github.com/opencv/opencv/pull/23467
The PR introduce configuration option to generate Java code with Cleaner interface for Java 9+ and old-fashion finalize() method for old Java and Android. Mat class and derivatives are manually written. The PR introduce 2 base classes for it depending on the generator configuration.
Pros:
1. No need to implement complex and error prone cleaner on library side.
2. No new CMake templates, easier to modify code in IDE.
Cons:
1. More generator branches and different code for modern desktop and Android.
TODO:
- [x] Add Java version check to cmake
- [x] Use Cleaners for ANDROID API 33+
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Fix frame seeking with negative DTS values in FFMPEG backend #27878
**Merge with extra**: https://github.com/opencv/opencv_extra/pull/1289
Fixes https://github.com/opencv/opencv/issues/27819
Fixes https://github.com/opencv/opencv/issues/23472
Accompanied by PR on https://github.com/opencv/opencv_extra/pull/1289
The FFmpeg backend fails to correctly seek in H.264 videos that contain negative DTS values in their initial frames. This is a valid encoding practice used by modern video encoders (such as DaVinci Resolve's current export) where B-frame reordering causes the first few frames to have negative DTS values.
When picture_pts is unavailable (AV_NOPTS_VALUE), the code falls back to using pkt_dts:
`picture_pts = packet_raw.pts != AV_NOPTS_VALUE_ ? packet_raw.pts : packet_raw.dts;`
If this DTS value is negative (which is legal per H.264 spec), it propagates through the frame number calculation:
`frame_number = dts_to_frame_number(picture_pts) - first_frame_number;`
This results in negative frame numbers, messing up seeking operations.
Solution implemented in this branch is a timestamp normalization similar to FFmpegs -avoid_negative_ts_make_zero flag:
- Calculate a global offset once on the first decoded frame by getting the minimum timestamp in either:
- Container start_time
- Stream start_time
- First observed timestamp (PTS, then DTS).
- Apply the offset consistently to all timestamps, shifting negative values to begin at 0 while keeping relative timing.
- Simplify timestamp converters to remove `start_time` subtractions since timestamps are pre-normalized.
This also includes a new test `videoio_ffmpeg.seek_with_negative_dts`
This test verifies that seeking behavior performs as expected on a file which has negative DTS values in the first frames.
A PR on opencv_extra accompanies this one with that testing file: https://github.com/opencv/opencv_extra/pull/1279
```
opencv_extra=ffmpeg-videoio-negative-dts-test-data
```
<cut/>
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Added 16U and 32F support in merge functions in photo module #28168
closes: https://github.com/opencv/opencv/issues/27873
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js: add C++17 requirement check for Emscripten 4.0.20+ #28179
Close https://github.com/opencv/opencv/issues/28178
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rvv_hal: fix flip inplace #28180
Fixes https://github.com/opencv/opencv/issues/28124
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satyam yadav
Alexander Smorkalov
Karnav Shah
Abhishek Gola
happy-capybara-man
Vincent Rabaud
ramukhsuya
Alexander Smorkalov
Dmitry Kurtaev
Brian Ferri
AdwaithBatchu
ramukhsuya
HARSH SUMAN
Alex
Kumataro
pratham-mcw
Yuantao Feng