Fixed matchTemplate function. #23585

modules/imgproc/src/templmatch.cpp

@@ -779,9 +779,11 @@ static void matchTemplateMask( InputArray _img, InputArray _templ, OutputArray _
     }
     if (mask.depth() == CV_8U)
     {
-        // To keep compatibility to other masks in OpenCV: CV_8U masks are binary masks
-        threshold(mask, mask, 0/*threshold*/, 1.0/*maxVal*/, THRESH_BINARY);
-        mask.convertTo(mask, CV_32F);
+        Mat mask_copy = mask.clone(); // Create a copy of the mask
+
+        threshold(mask_copy, mask_copy, 0/*threshold*/, 1.0/*maxVal*/, THRESH_BINARY);
+        mask_copy.convertTo(mask_copy, CV_32F);
+
     }
 
     Size corrSize(img.cols - templ.cols + 1, img.rows - templ.rows + 1);