From bc95f27e56d89e486c25e76db0573b610bee6496 Mon Sep 17 00:00:00 2001
From: Rostislav Vasilikhin <savuor@gmail.com>
Date: Thu, 2 May 2024 19:50:08 +0200
Subject: [PATCH] Merge pull request #25509 from savuor:rv/hal_otsu

HAL added for Otsu threshold #25509

fixes #25393

### 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
---
 modules/imgproc/src/hal_replacement.hpp | 19 +++++++++++++++++++
 modules/imgproc/src/thresh.cpp          | 11 ++++++++---
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/modules/imgproc/src/hal_replacement.hpp b/modules/imgproc/src/hal_replacement.hpp
index ca25fbb47d..28bfd31090 100644
--- a/modules/imgproc/src/hal_replacement.hpp
+++ b/modules/imgproc/src/hal_replacement.hpp
@@ -856,6 +856,25 @@ inline int hal_ni_threshold(const uchar* src_data, size_t src_step, uchar* dst_d
 #define cv_hal_threshold hal_ni_threshold
 //! @endcond
 
+/**
+   @brief Performs threshold filtering using threshold estimated by Otsu algorithm
+   @param src_data Source image data
+   @param src_step Source image step
+   @param dst_data Destination image data
+   @param dst_step Destination image step
+   @param width Source image width
+   @param height Source image height
+   @param depth Depths of source and destination image
+   @param maxValue Value assigned to the pixels for which the condition is satisfied
+   @param thresholdType Thresholding type
+   @param thresh Calculated threshold value
+*/
+inline int hal_ni_threshold_otsu(const uchar* src_data, size_t src_step, uchar* dst_data, size_t dst_step, int width, int height, int depth, double maxValue, int thresholdType, double* thresh) { return CV_HAL_ERROR_NOT_IMPLEMENTED; }
+
+//! @cond IGNORED
+#define cv_hal_threshold_otsu hal_ni_threshold_otsu
+//! @endcond
+
 /**
    @brief Calculate box filter
    @param src_data Source image data
diff --git a/modules/imgproc/src/thresh.cpp b/modules/imgproc/src/thresh.cpp
index 8d82c14a50..a8c89059a7 100644
--- a/modules/imgproc/src/thresh.cpp
+++ b/modules/imgproc/src/thresh.cpp
@@ -1545,6 +1545,10 @@ double cv::threshold( InputArray _src, OutputArray _dst, double thresh, double m
                 ocl_threshold(_src, _dst, thresh, maxval, type), thresh)
 
     Mat src = _src.getMat();
+
+    _dst.create( src.size(), src.type() );
+    Mat dst = _dst.getMat();
+
     int automatic_thresh = (type & ~cv::THRESH_MASK);
     type &= THRESH_MASK;
 
@@ -1553,6 +1557,10 @@ double cv::threshold( InputArray _src, OutputArray _dst, double thresh, double m
     {
         int src_type = src.type();
         CV_CheckType(src_type, src_type == CV_8UC1 || src_type == CV_16UC1, "THRESH_OTSU mode");
+
+        CALL_HAL_RET(thresholdOtsu, cv_hal_threshold_otsu, thresh, src.data, src.step, dst.data, dst.step,
+                     src.cols, src.rows, src_type, maxval, type);
+
         thresh = src.type() == CV_8UC1 ? getThreshVal_Otsu_8u( src )
                                        : getThreshVal_Otsu_16u( src );
     }
@@ -1562,9 +1570,6 @@ double cv::threshold( InputArray _src, OutputArray _dst, double thresh, double m
         thresh = getThreshVal_Triangle_8u( src );
     }
 
-    _dst.create( src.size(), src.type() );
-    Mat dst = _dst.getMat();
-
     if( src.depth() == CV_8U )
     {
         int ithresh = cvFloor(thresh);