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diff --git a/src/Tests_hough/HTCircleMa.m b/src/Tests_hough/HTCircleMa.m
new file mode 100644
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+++ b/src/Tests_hough/HTCircleMa.m
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+% Hough Transform for circles.
+% x_dir : the x component of the normalized gradient
+% y_dir : the y component of the normalized gradient
+% edges : a binary image with edge = 1
+% radius_range is a vector : [min, max]
+function [acc_votes, acc_radius] = HTCircleMa(x_dir, y_dir, edges, radius_range)
+
+    [rows, columns] = size(edges);
+    
+    acc_votes = zeros(rows, columns);
+    acc_radius = zeros(rows, columns);    
+    
+    indexes_edges = find(edges)';
+    s = size(edges);
+    
+    for r = radius_range(1):radius_range(2)
+        acc = zeros(rows, columns);
+        for i = indexes_edges
+            [y, x] = ind2sub(s, i);      
+            
+            x0 = round(x + x_dir(i) * r);
+            y0 = round(y + y_dir(i) * r);
+            
+            if x0 < columns && x0 > 0 && y0 < rows && y0 > 0
+                acc(y0, x0) = acc(y0, x0) + 1;
+            end
+        end
+        
+        for x = 1:columns
+            for y = 1:rows
+                if acc(y, x) > acc_votes(y, x)
+                    acc_votes(y, x) = acc(y, x);
+                    acc_radius(y, x) = r;
+                end
+            end
+        end        
+    end
+    
+    acc_votes = imgaussfilt(acc_votes, 1.0);
+end
+