From 1890157faa99b247cb0ba096c85beed44788e8ba Mon Sep 17 00:00:00 2001
From: Artem Saratovtsev <46279571+DumDereDum@users.noreply.github.com>
Date: Fri, 18 Feb 2022 17:58:58 +0300
Subject: [PATCH] Merge pull request #21635 from DumDereDum:issue_21595_3.4

Issue 21595 fix 3.4 branch

* bug fix; add test

* rewrite tests avoiding vector in tests
---
 modules/imgproc/src/histogram.cpp        |  3 ++-
 modules/imgproc/test/test_histograms.cpp | 32 ++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/modules/imgproc/src/histogram.cpp b/modules/imgproc/src/histogram.cpp
index e66e2e2d23..404bd43188 100644
--- a/modules/imgproc/src/histogram.cpp
+++ b/modules/imgproc/src/histogram.cpp
@@ -909,7 +909,8 @@ static bool ipp_calchist(const Mat &image, Mat &hist, int histSize, const float*
 #endif
 
     // IPP_DISABLE_HISTOGRAM - https://github.com/opencv/opencv/issues/11544
-    if (uniform && (ranges[0][1] - ranges[0][0]) != histSize)
+    // and https://github.com/opencv/opencv/issues/21595
+    if ((uniform && (ranges[0][1] - ranges[0][0]) != histSize) || abs(ranges[0][0]) != cvFloor(ranges[0][0]))
         return false;
 
     Mat ihist = hist;
diff --git a/modules/imgproc/test/test_histograms.cpp b/modules/imgproc/test/test_histograms.cpp
index afe6e53603..e3316df026 100644
--- a/modules/imgproc/test/test_histograms.cpp
+++ b/modules/imgproc/test/test_histograms.cpp
@@ -1993,6 +1993,38 @@ TEST(Imgproc_Hist_Calc, badarg)
     EXPECT_NO_THROW(cv::calcBackProject(&img, 1, channels, hist, backProj, NULL, 1, true));
 }
 
+TEST(Imgproc_Hist_Calc, IPP_ranges_with_equal_exponent_21595)
+{
+    const int channels[] = { 0 };
+    float range1[] = { -0.5f, 1.5f };
+    const float* ranges[] = { range1 };
+    const int hist_size[] = { 2 };
+
+    uint8_t m[1][6] = { { 0, 1, 0, 1 , 1, 1 } };
+    cv::Mat images_u = Mat(1, 6, CV_8UC1, m);
+    cv::Mat histogram_u;
+    cv::calcHist(&images_u, 1, channels, noArray(), histogram_u, 1, hist_size, ranges);
+
+    ASSERT_EQ(histogram_u.at<float>(0), 2.f) << "0 not counts correctly, res: " << histogram_u.at<float>(0);
+    ASSERT_EQ(histogram_u.at<float>(1), 4.f) << "1 not counts correctly, res: " << histogram_u.at<float>(0);
+}
+
+TEST(Imgproc_Hist_Calc, IPP_ranges_with_nonequal_exponent_21595)
+{
+    const int channels[] = { 0 };
+    float range1[] = { -1.3f, 1.5f };
+    const float* ranges[] = { range1 };
+    const int hist_size[] = { 3 };
+
+    uint8_t m[1][6] = { { 0, 1, 0, 1 , 1, 1 } };
+    cv::Mat images_u = Mat(1, 6, CV_8UC1, m);
+    cv::Mat histogram_u;
+    cv::calcHist(&images_u, 1, channels, noArray(), histogram_u, 1, hist_size, ranges);
+
+    ASSERT_EQ(histogram_u.at<float>(0), 0.f) << "not equal to zero, res: " << histogram_u.at<float>(0);
+    ASSERT_EQ(histogram_u.at<float>(1), 2.f) << "0 not counts correctly, res: " << histogram_u.at<float>(1);
+    ASSERT_EQ(histogram_u.at<float>(2), 4.f) << "1 not counts correctly, res: " << histogram_u.at<float>(2);
+}
 
 }} // namespace
 /* End Of File */