def test_bimodal_multiotsu_hist():
for name in ['camera', 'moon', 'coins', 'text', 'clock', 'page']:
img = cp.array(getattr(data, name)())
assert threshold_otsu(img) == threshold_multiotsu(img, 2)
for name in ['chelsea', 'coffee', 'astronaut', 'rocket']:
img = rgb2gray(cp.array(getattr(data, name)()))
assert threshold_otsu(img) == threshold_multiotsu(img, 2)
def test_multiotsu_output():
image = cp.zeros((100, 100), dtype='int')
coords = [(25, 25), (50, 50), (75, 75)]
values = [64, 128, 192]
for coor, val in zip(coords, values):
rr, cc = disk(coor, 20)
rr, cc = cp.asarray(rr), cp.asarray(cc)
image[rr, cc] = val
thresholds = [0, 64, 128]
assert_array_equal(thresholds, threshold_multiotsu(image, classes=4))
def test_check_multiotsu_results():
# fmt: off
image = 0.25 * cp.array([[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4]])
# fmt: on
for idx in range(3, 6):
thr_multi = threshold_multiotsu(image,
classes=idx)
assert len(thr_multi) == idx - 1
def test_multiotsu_more_classes_then_values():
img = cp.ones((10, 10), dtype=cp.uint8)
with testing.raises(ValueError):
threshold_multiotsu(img, classes=2)
img[:, 3:] = 2
with testing.raises(ValueError):
threshold_multiotsu(img, classes=3)
img[:, 6:] = 3
with testing.raises(ValueError):
threshold_multiotsu(img, classes=4)
def test_multiotsu_astro_image():
img = util.img_as_ubyte(astronautd)
with expected_warnings(['grayscale']):
assert_array_almost_equal(threshold_multiotsu(img), [58, 149])