def test_q3a_convert_rgb_to_greyscale():
colour_file = pathlib.Path() / 'samples' / 'rocket.ppm'
grey_file = pathlib.Path() / 'samples' / 'rocket-greyscale.pgm'
image = imread(str(colour_file))
greyscale = rgb2grey(image)
expected = imread(str(grey_file))
assert greyscale.dtype == np.uint8
imwrite(pathlib.Path() / 'test.pgm', greyscale)
assert_array_equal(greyscale, expected)
def test_q1b_read_colour_image():
expected = np.array([
[[255, 0, 0],
[0, 0, 0],
[255, 255, 255],
[255, 255, 255]],
[[0, 0, 0],
[0, 255, 0],
[0, 0, 255],
[255, 255, 255]],
[[0, 0, 0],
[255, 0, 0],
[0, 255, 255],
[0, 0, 0]],
[[255, 255, 0],
[0, 0, 0],
[0, 0, 0],
[255, 0, 255]]
], dtype=np.uint8)
filename = pathlib.Path() / 'samples' / 'colour.ppm'
image = imread(filename.absolute())
assert_array_equal(expected, image)
def test_q4a_convert_grey_to_pseudo_colour():
grey_file = pathlib.Path() / 'samples' / 'rocket-greyscale.pgm'
image = imread(str(grey_file))
rgb = grey2rgb(image)
assert rgb.dtype == np.uint8
assert rgb.ndim == 3
assert rgb.shape[2] == 3
for i in range(3):
assert_array_equal(rgb[:, :, i], image)
def test_q1a_read_greyscale_image():
expected = np.array([
[255, 0, 255, 255],
[0, 255, 255, 255],
[0, 255, 255, 0],
[255, 0, 0, 255]
], dtype=np.uint8)
filename = pathlib.Path() / 'samples' / 'greyscale.pgm'
image = imread(filename.absolute())
assert_array_equal(expected, image)
def convert_image(rgb_image, grey_image):
image = imread(rgb_image)
greyscale = rgb2grey(image)
imwrite(grey_image, greyscale)
def test_q1c_unsupported_type_raises_exception():
filename = pathlib.Path() / 'samples' / 'colour-binary.pbm'
with pytest.raises(ValueError):
imread(filename.absolute())