Merge pull request #26831 from shyama7004:fix-denoising.cpp

Added 16-bit support to fastNlMeansDenoising and updated tests #26831

Fixes : #26582

### 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
- [ ] 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/photo/src/denoising.cpp

@@ -249,16 +249,15 @@ static void fastNlMeansDenoisingMulti_( const std::vector<Mat>& srcImgs, Mat& ds
     int hn = (int)h.size();
     double granularity = (double)std::max(1., (double)dst.total()/(1 << 16));
 
-    switch (srcImgs[0].type())
-    {
-        case CV_8U:
+    switch (CV_MAT_CN(srcImgs[0].type())) {
+        case 1:
             parallel_for_(cv::Range(0, srcImgs[0].rows),
-                          FastNlMeansMultiDenoisingInvoker<uchar, IT, UIT, D, int>(
+                          FastNlMeansMultiDenoisingInvoker<ST, IT, UIT, D, int>(
                               srcImgs, imgToDenoiseIndex, temporalWindowSize,
                               dst, templateWindowSize, searchWindowSize, &h[0]),
                           granularity);
             break;
-        case CV_8UC2:
+        case 2:
             if (hn == 1)
                 parallel_for_(cv::Range(0, srcImgs[0].rows),
                               FastNlMeansMultiDenoisingInvoker<Vec<ST, 2>, IT, UIT, D, int>(
@@ -272,7 +271,7 @@ static void fastNlMeansDenoisingMulti_( const std::vector<Mat>& srcImgs, Mat& ds
                                   dst, templateWindowSize, searchWindowSize, &h[0]),
                               granularity);
             break;
-        case CV_8UC3:
+        case 3:
             if (hn == 1)
                 parallel_for_(cv::Range(0, srcImgs[0].rows),
                               FastNlMeansMultiDenoisingInvoker<Vec<ST, 3>, IT, UIT, D, int>(
@@ -286,7 +285,7 @@ static void fastNlMeansDenoisingMulti_( const std::vector<Mat>& srcImgs, Mat& ds
                                   dst, templateWindowSize, searchWindowSize, &h[0]),
                               granularity);
             break;
-        case CV_8UC4:
+        case 4:
             if (hn == 1)
                 parallel_for_(cv::Range(0, srcImgs[0].rows),
                               FastNlMeansMultiDenoisingInvoker<Vec<ST, 4>, IT, UIT, D, int>(
@@ -300,9 +299,9 @@ static void fastNlMeansDenoisingMulti_( const std::vector<Mat>& srcImgs, Mat& ds
                                   dst, templateWindowSize, searchWindowSize, &h[0]),
                               granularity);
             break;
-        default:
+       default:
             CV_Error(Error::StsBadArg,
-                "Unsupported image format! Only CV_8U, CV_8UC2, CV_8UC3 and CV_8UC4 are supported");
+                     "Unsupported number of channels! Only 1, 2, 3, and 4 are supported");
     }
 }
 

modules/photo/test/test_denoising.cpp

@@ -165,4 +165,33 @@ TEST(Photo_Denoising, speed)
     printf("execution time: %gms\n", t*1000./getTickFrequency());
 }
 
+// Related issue : https://github.com/opencv/opencv/issues/26582
+TEST(Photo_DenoisingGrayscaleMulti16bitL1, regression)
+{
+    const int imgs_count = 3;
+    string folder = string(cvtest::TS::ptr()->get_data_path()) + "denoising/";
+
+    vector<Mat> original_8u(imgs_count);
+    vector<Mat> original_16u(imgs_count);
+    for (int i = 0; i < imgs_count; i++)
+    {
+        string original_path = format("%slena_noised_gaussian_sigma=20_multi_%d.png", folder.c_str(), i);
+        original_8u[i] = imread(original_path, IMREAD_GRAYSCALE);
+        ASSERT_FALSE(original_8u[i].empty()) << "Could not load input image " << original_path;
+        original_8u[i].convertTo(original_16u[i], CV_16U);
+    }
+
+    Mat result_8u, result_16u;
+    std::vector<float> h = {15};
+    fastNlMeansDenoisingMulti(original_8u, result_8u, /*imgToDenoiseIndex*/ imgs_count / 2, /*temporalWindowSize*/ imgs_count, h, 7, 21, NORM_L1);
+    fastNlMeansDenoisingMulti(original_16u, result_16u, /*imgToDenoiseIndex*/ imgs_count / 2, /*temporalWindowSize*/ imgs_count, h, 7, 21, NORM_L1);
+    DUMP(result_8u, "8u.res.png");
+    DUMP(result_16u, "16u.res.png");
+
+    cv::Mat expected;
+    result_8u.convertTo(expected, CV_16U);
+
+    EXPECT_MAT_NEAR(result_16u, expected, 1);
+}
+
 }} // namespace

modules/photo/test/test_precomp.hpp

@@ -5,6 +5,7 @@
 #define __OPENCV_TEST_PRECOMP_HPP__
 
 #include "opencv2/ts.hpp"
+#include "opencv2/ts/ocl_test.hpp"
 #include "opencv2/photo.hpp"
 
 #endif