Added flag to GaussianBlur for faster but not bit-exact implementation by asmorkalov · Pull Request #25792 · opencv/opencv

asmorkalov · 2024-06-20T09:25:35Z

Rationale:
Current implementation of GaussianBlur is almost always bit-exact. It helps to get predictable results according platforms, but prohibits most of approximations and optimization tricks.

The patch converts borderType parameter to more generic flags and introduces GAUSS_ALLOW_APPROXIMATIONS flag to allow not bit-exact implementation. With the flag IPP and generic HAL implementation are called first. The flag naming and location is a subject for discussion.

Replaces #22073
Possibly related issue: #24135

Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

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
There is a reference to the original bug report and related work
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

modules/imgproc/include/opencv2/imgproc.hpp

asmorkalov · 2024-06-21T07:07:05Z

Discussion result:

move enum to core
dedicated parameter for perf hint, do not mix with border type.
check python and java bindings

asmorkalov · 2024-06-26T08:45:13Z

@mshabunin @opencv-alalek @vpisarev I reworked interface as discussed offline and added accuracy tests for IPP branch. Could you take a look?

modules/imgproc/src/smooth.dispatch.cpp

modules/core/include/opencv2/core.hpp

modules/imgproc/include/opencv2/imgproc.hpp

…mentation.

CMakeLists.txt

modules/imgproc/include/opencv2/imgproc.hpp

opencv-alalek · 2024-07-11T07:27:26Z

modules/imgproc/test/test_smooth_bitexact.cpp

+    cv::absdiff(dst, gt, diff);
+    cv::Mat flatten_diff = diff.reshape(1, diff.rows);
+
+    int nz = countNonZero(flatten_diff);


norm is faster than countNonZero approach.

Use relative NORM_L1/L2 and NORM_INF instead.

I intentionally split the check on min-max deviation and amount of different pixels.

EXPECT_LE(max_val, 2); // expectes results floating +-1

comment doesn't follow to the check anyway.

NORM_INF <=1 works perfect.

With 1-limited NORM_INF, we could use NORM_L1 + RELATIVE to define the part of pixels of different values.

modules/core/include/opencv2/core.hpp

asmorkalov · 2024-07-11T08:38:31Z

@opencv-alalek I fixed your review notes. Please take a look again.

opencv-alalek · 2024-07-14T23:31:23Z

modules/core/include/opencv2/core.hpp

+    ALGO_APPROX = 2, //!< Allow alternative approximations to get faster implementation. Behaviour and result depends on a platform
+};
+
+/*! @brief Returns ImplementationHint selected by default, a.k.a. `IMPL_DEFAULT` defined during OpenCV compilation.


ImplementationHint

not renamed

IMPL_DEFAULT

What is that?

opencv-alalek · 2024-07-14T23:31:37Z

modules/core/include/opencv2/core.hpp

+*/
+enum AlgorithmHint {
+    ALGO_DEFAULT = 0, //!< Default algorithm behaviour defined during OpenCV build
+    ALGO_ACCURATE = 1, //!< Use generic portable implementation


ALGO_HINT_ then.

opencv-alalek · 2024-07-14T23:32:43Z

modules/core/src/system.cpp

 #include <iostream>
 #include <ostream>

+#include <opencv2/core.hpp>


To be removed.

opencv-alalek · 2024-07-14T23:35:25Z

modules/core/include/opencv2/core.hpp

+
+/*! @brief Returns ImplementationHint selected by default, a.k.a. `IMPL_DEFAULT` defined during OpenCV compilation.
+ */
+CV_EXPORTS_W AlgorithmHint getDefaultAlgorithmHint();


Should go to utility.hpp somewhere near setUseOptimized()

setUseOptimized() should also control behavior of that:

setUseOptimized(false) disables these hints and use accurate versions.

opencv-alalek · 2024-07-14T23:40:06Z

modules/imgproc/test/test_smooth_bitexact.cpp

+    cv::absdiff(dst, gt, diff);
+    cv::Mat flatten_diff = diff.reshape(1, diff.rows);
+
+    int nz = countNonZero(flatten_diff);


EXPECT_LE(max_val, 2); // expectes results floating +-1

comment doesn't follow to the check anyway.

NORM_INF <=1 works perfect.

With 1-limited NORM_INF, we could use NORM_L1 + RELATIVE to define the part of pixels of different values.

Added xxxApprox overloads for YUV color conversions in HAL and AlgorithmHint to cvtColor #25932 The xxxApprox to implement HAL functions with less bits for arithmetic of FP. The hint was introduced in #25792 and #25911 ### Pull Request Readiness Checklist See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request - [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 - [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

Added flag to GaussianBlur for faster but not bit-exact implementation opencv#25792 Rationale: Current implementation of GaussianBlur is almost always bit-exact. It helps to get predictable results according platforms, but prohibits most of approximations and optimization tricks. The patch converts `borderType` parameter to more generic `flags` and introduces `GAUSS_ALLOW_APPROXIMATIONS` flag to allow not bit-exact implementation. With the flag IPP and generic HAL implementation are called first. The flag naming and location is a subject for discussion. Replaces opencv#22073 Possibly related issue: opencv#24135 ### Pull Request Readiness Checklist See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request - [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 - [ ] 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. - [ ] The feature is well documented and sample code can be built with the project CMake

Added xxxApprox overloads for YUV color conversions in HAL and AlgorithmHint to cvtColor opencv#25932 The xxxApprox to implement HAL functions with less bits for arithmetic of FP. The hint was introduced in opencv#25792 and opencv#25911 ### Pull Request Readiness Checklist See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request - [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 - [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

Added flag to GaussianBlur for faster but not bit-exact implementation opencv#25792 Rationale: Current implementation of GaussianBlur is almost always bit-exact. It helps to get predictable results according platforms, but prohibits most of approximations and optimization tricks. The patch converts `borderType` parameter to more generic `flags` and introduces `GAUSS_ALLOW_APPROXIMATIONS` flag to allow not bit-exact implementation. With the flag IPP and generic HAL implementation are called first. The flag naming and location is a subject for discussion. Replaces opencv#22073 Possibly related issue: opencv#24135 See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request - [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 - [ ] 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. - [ ] The feature is well documented and sample code can be built with the project CMake

Added flag to GaussianBlur for faster but not bit-exact implementation opencv#25792 Rationale: Current implementation of GaussianBlur is almost always bit-exact. It helps to get predictable results according platforms, but prohibits most of approximations and optimization tricks. The patch converts `borderType` parameter to more generic `flags` and introduces `GAUSS_ALLOW_APPROXIMATIONS` flag to allow not bit-exact implementation. With the flag IPP and generic HAL implementation are called first. The flag naming and location is a subject for discussion. Replaces opencv#22073 Possibly related issue: opencv#24135 ### Pull Request Readiness Checklist See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request - [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 - [ ] 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. - [ ] The feature is well documented and sample code can be built with the project CMake

Added xxxApprox overloads for YUV color conversions in HAL and AlgorithmHint to cvtColor opencv#25932 The xxxApprox to implement HAL functions with less bits for arithmetic of FP. The hint was introduced in opencv#25792 and opencv#25911 ### Pull Request Readiness Checklist See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request - [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 - [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

asmorkalov added optimization category: imgproc RFC labels Jun 20, 2024

asmorkalov added this to the 4.11.0 milestone Jun 20, 2024

asmorkalov requested review from mshabunin, opencv-alalek and vpisarev June 20, 2024 09:25

asmorkalov force-pushed the as/HAL_fast_GaussianBlur branch 2 times, most recently from 1c62df7 to b5df286 Compare June 20, 2024 10:16

asmorkalov added the pr: Discussion Required label Jun 20, 2024

asmorkalov changed the title ~~Added flag to GaussianBlur for faster but not bit-exact implementation.~~ Added flag to GaussianBlur for faster but not bit-exact implementation Jun 20, 2024

asmorkalov force-pushed the as/HAL_fast_GaussianBlur branch 2 times, most recently from 671ce14 to ea56bd9 Compare June 20, 2024 12:37

asmorkalov added the pr: needs test New functionality requires minimal tests set label Jun 20, 2024

vpisarev reviewed Jun 21, 2024

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asmorkalov added category: core test and removed pr: Discussion Required pr: needs test New functionality requires minimal tests set labels Jun 25, 2024

mshabunin reviewed Jun 26, 2024

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vpisarev reviewed Jun 28, 2024

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modules/core/include/opencv2/core.hpp Show resolved Hide resolved

vpisarev reviewed Jun 28, 2024

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opencv-alalek reviewed Jun 28, 2024

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asmorkalov added 3 commits July 10, 2024 13:39

Added flag to GaussianBlur for faster but not bit-exact implementation.

f702da6

Implemented alternative interface for implementation hints.

12a5914

Accuracy test for GaussianBlur with IMPL_ALLOW_APPROXIMATION.

771034c

asmorkalov force-pushed the as/HAL_fast_GaussianBlur branch from a753443 to 8fa2e47 Compare July 10, 2024 11:49

asmorkalov added 3 commits July 10, 2024 15:20

Added Implementation hint to test system reports and CMake flags docu…

a7ce249

…mentation.

Code review fixes.

bf8a99d

Code review fixes.

a677218

vpisarev self-requested a review July 10, 2024 19:22

vpisarev approved these changes Jul 10, 2024

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opencv-alalek reviewed Jul 11, 2024

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asmorkalov added feature and removed RFC labels Jul 11, 2024

asmorkalov force-pushed the as/HAL_fast_GaussianBlur branch from a47f442 to ee840b5 Compare July 11, 2024 09:48

Code review fixes.

13b6caa

asmorkalov force-pushed the as/HAL_fast_GaussianBlur branch from ee840b5 to 13b6caa Compare July 11, 2024 11:04

asmorkalov merged commit 15783d6 into opencv:4.x Jul 12, 2024

Kumataro mentioned this pull request Jul 13, 2024

core: hal: avoid to use _tzcnt_u32 for ARM64EC #25903

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opencv-alalek reviewed Jul 14, 2024

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savuor mentioned this pull request Nov 1, 2024

Recent HAL changes ported to 4.9 #26395

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asmorkalov moved this to Done in OpenCV 4.x HAL improvement Sep 11, 2025

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asmorkalov commented Jun 20, 2024 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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asmorkalov commented Jun 21, 2024

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asmorkalov commented Jul 11, 2024

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asmorkalov commented Jun 20, 2024 •

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