Add some tests on different variations of Hough algorithm.

[master-thesis.git] / src / Tests_hough / HTEllipse.m

diff --git a/src/Tests_hough/HTEllipse.m b/src/Tests_hough/HTEllipse.m
new file mode 100644 (file)
index 0000000..908f230
--- /dev/null
+++ b/src/Tests_hough/HTEllipse.m
@@ -0,0 +1,56 @@
+% Hough Transform for circles.
+% img : logical image, zeros are the circles edges
+% radius_range is a vector : [min, max]
+function [acc_votes, acc_radius1, acc_radius2, acc_alpha] = HTEllipse(img, radius_range)
+
+    [rows, columns] = size(img);
+    
+    acc_votes = zeros(rows, columns);
+    acc_radius1 = zeros(rows, columns);
+    acc_radius2 = zeros(rows, columns);
+    acc_alpha = zeros(rows, columns);
+    
+    alpha_range = linspace(0, pi / 2, 8);
+    alpha_range(end) = [];
+    
+    phi_range = linspace(0, 2 * pi, 32);
+    phi_range(end) = [];
+    
+    indexes_non_zero = find(img)';
+    s = size(img);
+    
+    for alpha = alpha_range
+        transform_mat = [cos(alpha) -sin(alpha); sin(alpha) cos(alpha)];        
+        for r1 = radius_range(1):radius_range(2)
+            for r2 = radius_range(1):radius_range(2)
+                acc = zeros(rows, columns);
+                for i = indexes_non_zero
+                    [y, x] = ind2sub(s, i);
+                    for phi = phi_range
+                        p0 = [x; y] - transform_mat * [r1 * cos(phi); r2 * sin(phi)];
+                        x0 = round(p0(1));
+                        y0 = round(p0(2));
+
+                        if x0 < columns && x0 > 0 && y0 < rows && y0 > 0
+                            acc(y0, x0) = acc(y0, x0) + 1;
+                        end
+                    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_radius1(y, x) = r1;
+                            acc_radius2(y, x) = r2;
+                            acc_alpha(y, x) = alpha;
+                        end
+                    end
+                end      
+            end
+        end
+    end
+    
+    acc_votes = imgaussfilt(acc_votes, 1.0);
+end
+