def test_wikipedia(self):
"""Test with example values from Wikipedia
https://en.wikipedia.org/wiki/Bilinear_interpolation#Application_in_image_processing"""
data = np.array([[91, 210], [162, 95]])
self.assertEqual(bilinear_interpolation(0.5, 0, data), 150.5)
self.assertEqual(bilinear_interpolation(0.5, 1, data), 128.5)
self.assertAlmostEqual(bilinear_interpolation(0.5, 0.2, data), 146.1)
def test_opencv(self):
"""Test using opencv resize()"""
np.random.seed(1)
img_np = np.random.random([2, 2])
img_np = np.round(np.multiply(img_np, 100))
print(img_np)
img_cv = cv2.resize(img_np, (3, 3), interpolation=cv2.INTER_LINEAR)
print(img_cv)
self.assertAlmostEqual(img_cv[0, 0],
bilinear_interpolation(0, 0, img_np))
self.assertAlmostEqual(img_cv[0, 1],
bilinear_interpolation(0.5, 0, img_np))
self.assertAlmostEqual(img_cv[0, 2],
bilinear_interpolation(1, 0, img_np))
self.assertAlmostEqual(img_cv[1, 0],
bilinear_interpolation(0, 0.5, img_np))
self.assertAlmostEqual(img_cv[1, 1],
bilinear_interpolation(0.5, 0.5, img_np))
self.assertAlmostEqual(img_cv[1, 2],
bilinear_interpolation(1, 0.5, img_np))
self.assertAlmostEqual(img_cv[2, 0],
bilinear_interpolation(0, 1, img_np))
self.assertAlmostEqual(img_cv[2, 1],
bilinear_interpolation(0.5, 1, img_np))
self.assertAlmostEqual(img_cv[2, 2],
bilinear_interpolation(1, 1, img_np))
def test_interpolation_x_y_direction(self):
"""Test interpolation in x- and y-direction."""
self.assertEqual(bilinear_interpolation(0.5, 0.5, self.image), 2)
self.assertEqual(bilinear_interpolation(1.5, 0.5, self.image), 3)
self.assertEqual(bilinear_interpolation(0.5, 1.5, self.image), 5)
self.assertEqual(bilinear_interpolation(1.5, 1.5, self.image), 6)
self.assertAlmostEqual(bilinear_interpolation(0.1, 0.1, self.image),
0.4)
self.assertEqual(bilinear_interpolation(1.9, 1.9, self.image), 7.6)
def test_interpolation_outside_image(self):
"""Test if error is raised when the position is outside of the image."""
with self.assertRaises(ValueError):
bilinear_interpolation(2.1, 0, self.image)
with self.assertRaises(ValueError):
bilinear_interpolation(0, 2.1, self.image)
def test_interpolation_error_negativ(self):
"""Test if errors are properly raised."""
with self.assertRaises(ValueError):
bilinear_interpolation(-1, 0, self.image)
with self.assertRaises(ValueError):
bilinear_interpolation(0, -1, self.image)
def test_interpolation_y_direction(self):
"""Test interpolation in y-direction."""
self.assertEqual(bilinear_interpolation(0, 0.5, self.image), 1.5)
self.assertEqual(bilinear_interpolation(0, 1.5, self.image), 4.5)
self.assertEqual(bilinear_interpolation(2, 0.6, self.image), 3.8)
self.assertEqual(bilinear_interpolation(2, 1.5, self.image), 6.5)
def test_interpolation_x_direction(self):
"""Test interpolation in x-direction."""
self.assertEqual(bilinear_interpolation(0.5, 0, self.image), 0.5)
self.assertEqual(bilinear_interpolation(1.4, 0, self.image), 1.4)
self.assertEqual(bilinear_interpolation(0.5, 2, self.image), 6.5)
self.assertEqual(bilinear_interpolation(1.4, 2, self.image), 7.4)
def test_no_interpolation(self):
"""Test that no scaling produces no effect."""
self.assertEqual(bilinear_interpolation(0, 0, self.image), 0)
self.assertEqual(bilinear_interpolation(1, 1, self.image), 4)
self.assertEqual(bilinear_interpolation(2, 2, self.image), 8)
