def extract(self, watermarked_array, coeficient_index):
msg = ''
block_manager = BlocksImage(watermarked_array)
for block in range(block_manager.max_num_blocks()):
msg += self.__extract__(block, coeficient_index)
return utils.bin2char(msg)
def insert(self, cover_array, msg=None):
'''
obj.insert(cover_array, msg) => (np.numpy): Return a watermarked
work (stego work) with specified message.
'''
# Initial Values
count = 0
# Binary message
bin_msg = utils.char2bin(msg)
# Creating copy
watermarked_array = np.copy(cover_array)
# Depth of the image
if len(watermarked_array.shape) == 2:
red_watermarked_array = watermarked_array
else:
# Red component
red_watermarked_array = watermarked_array[:, :, 0]
# Instance
block_instace_8x8 = BlocksImage(red_watermarked_array)
# Increasing the hash function
# self.hashf = increase(self.hashf, block_instace_8x8.max_num_blocks())
# Checking the embedding capacity
embd_cap = block_instace_8x8.max_num_blocks() * 8
if len(bin_msg) > embd_cap:
raise ExceededCapacity
for i in range(block_instace_8x8.max_num_blocks()):
block8x8 = block_instace_8x8[i]
block_transf8x8 = self.ortho_matrix.direct(block8x8)
vac = utils.vzig_zag_scan(block_transf8x8)
for k in range(1, 9):
# TODO: l deleted
# vac[k] = np.sign(vac[k]) * utils.replace(
# abs(round(vac[k])), bin_msg[i % (len(bin_msg))]
# )
if count < len(bin_msg):
vac[k] = np.sign(vac[k]) * utils.replace(
abs(round(vac[k])), bin_msg[count])
count += 1
block_transf8x8 = utils.mzig_zag_scan(vac)
block_instace_8x8[i] = self.ortho_matrix.inverse(block_transf8x8)
return watermarked_array
def extract(self, ws_array, msg=None):
'''
obj.get(watermarked_array) => (np.numpy): Return the message.
'''
extracted_lsb = ''
# Depth of the image
if len(ws_array.shape) == 2:
red_ws_array = ws_array
else:
# Red component
red_ws_array = ws_array[:, :, 0]
# Instance
block_instace_8x8 = BlocksImage(red_ws_array)
# Extraction process
for i in range(block_instace_8x8.max_num_blocks()):
block8x8 = block_instace_8x8[i]
block_transf8x8 = self.ortho_matrix.direct(block8x8)
vac = utils.vzig_zag_scan(block_transf8x8)
for k in range(1, 9):
extracted_lsb += utils.ext_lsb(abs(round(vac[k])))
return utils.bin2char(extracted_lsb)
def test_element_modification(self):
image = np.array([[0.98838329, 0.92974977, 0.40523466, 0.41932678],
[0.40426586, 0.44543487, 0.67170983, 0.46135769],
[0.85925337, 0.59646605, 0.38249919, 0.8737707],
[0.85925337, 0.59646605, 0.45148745, 0.79845514]])
new_block = np.array([[0.40426582, 0.92974977],
[0.40426586, 0.44543487]])
blocks = BlocksImage(image, 2, 2)
block = blocks[0]
block[0][0] = 0.40426582
np.testing.assert_array_equal(blocks[0], new_block)
def extract(self, ws_work, block_shape=(8, 8), **kwargs):
'''
Get bit hidden an return it
Arguments:
index -- index of coefficient where bit will be extracted
'''
msg = ''
blocks = BlocksImage(ws_work, *block_shape)
for block in blocks:
bit = self.hider.extract(block, **kwargs)
msg += str(bit)
return msg
def test_set_block(self):
image = np.array([[
0.72996436, 0.30220469, 0.26302874, 0.45926106, 0.83229292,
0.36547379, 0.04903042, 0.80401489
],
[
0.95165122, 0.0834489, 0.6329711, 0.70563593,
0.30838541, 0.85019345, 0.82915152, 0.66390158
],
[
0.73101532, 0.48981373, 0.23543479, 0.34432725,
0.64965507, 0.56053218, 0.87013326, 0.31057878
],
[
0.25541202, 0.7590065, 0.34833583, 0.87539685,
0.15707788, 0.12932102, 0.82317562, 0.27748149
],
[
0.12185236, 0.46868408, 0.95256657, 0.11167148,
0.14111763, 0.20679031, 0.38810133, 0.86408796
],
[
0.22420372, 0.69550787, 0.97781245, 0.65326647,
0.86442453, 0.82161094, 0.09722554, 0.69971431
],
[
0.08751724, 0.77511339, 0.77809499, 0.31933827,
0.24950535, 0.83073389, 0.35378153, 0.24732298
],
[
0.17390554, 0.83968645, 0.35554425, 0.83599189,
0.87064086, 0.84453971, 0.96192682, 0.79401981
]])
new_block = np.array([[0.4949508, 0.46024612],
[0.83870684, 0.36445031]])
modified_image = np.copy(image)
modified_image[4, 2] = 0.4949508
modified_image[4, 3] = 0.46024612
modified_image[5, 2] = 0.83870684
modified_image[5, 3] = 0.36445031
blocks = BlocksImage(image, 2, 2)
blocks[9] = new_block
np.testing.assert_array_equal(image, modified_image)
def insert(self, cover, msg, block_shape=(8, 8), **kwargs):
'''
Hide a bit
Arguments:
bit -- bit to hide
index -- index of coefficient where bit will be hidden
'''
data = np.copy(cover)
blocks = BlocksImage(data, *block_shape)
for i in range(len(msg)):
try:
blocks[i] = self.hider.insert(blocks[i], msg[i], **kwargs)
except IndexError as e:
raise ValueError("Capacity exceded.") from e
return data
def test_block_image_is_iterable(self):
'''
Test capacity of iterate over the blocks.
'''
image = np.array([[0.98838329, 0.92974977, 0.40523466, 0.41932678],
[0.40426586, 0.44543487, 0.67170983, 0.46135769],
[0.85925337, 0.59646605, 0.38249919, 0.8737707],
[0.85925337, 0.59646605, 0.45148745, 0.79845514]])
expected = [
np.array([[0.98838329, 0.92974977], [0.40426586, 0.44543487]]),
np.array([[0.40523466, 0.41932678], [0.67170983, 0.46135769]]),
np.array([[0.85925337, 0.59646605], [0.85925337, 0.59646605]]),
np.array([[0.38249919, 0.8737707], [0.45148745, 0.79845514]]),
]
blocks = BlocksImage(image, 2, 2)
for index, block in enumerate(blocks):
np.testing.assert_array_equal(block, expected[index])
def test_set_block_out_of_range(self):
image = np.array([[
0.72996436, 0.30220469, 0.26302874, 0.45926106, 0.83229292,
0.36547379, 0.04903042, 0.80401489
],
[
0.95165122, 0.0834489, 0.6329711, 0.70563593,
0.30838541, 0.85019345, 0.82915152, 0.66390158
],
[
0.73101532, 0.48981373, 0.23543479, 0.34432725,
0.64965507, 0.56053218, 0.87013326, 0.31057878
],
[
0.25541202, 0.7590065, 0.34833583, 0.87539685,
0.15707788, 0.12932102, 0.82317562, 0.27748149
],
[
0.12185236, 0.46868408, 0.95256657, 0.11167148,
0.14111763, 0.20679031, 0.38810133, 0.86408796
],
[
0.22420372, 0.69550787, 0.97781245, 0.65326647,
0.86442453, 0.82161094, 0.09722554, 0.69971431
],
[
0.08751724, 0.77511339, 0.77809499, 0.31933827,
0.24950535, 0.83073389, 0.35378153, 0.24732298
],
[
0.17390554, 0.83968645, 0.35554425, 0.83599189,
0.87064086, 0.84453971, 0.96192682, 0.79401981
]])
new_block = np.array([[0.4949508, 0.46024612],
[0.83870684, 0.36445031]])
blocks = BlocksImage(image, 2, 2)
with self.assertRaises(IndexError, msg="There is no such block"):
blocks[16] = new_block
def insert(self, cover_array, msg, coeficient_index):
# Binary data
bin_msg = utils.char2bin(msg)
# Cover copy and block generation
watermarked_array = np.copy(cover_array)
block_instance_8x8 = BlocksImage(watermarked_array)
# Checking the embedding capacity
embd_cap = block_instance_8x8.max_num_blocks()
self.validate_capacity(bin_msg, embd_cap)
# insertion process
for index, bit in enumerate(bin_msg):
block8x8 = block_instance_8x8.get_block(index)
block_transf8x8 = self.__insert__(bit, block8x8, coeficient_index)
block_instance_8x8.set_block(
self.ortho_matrix.inverse(block_transf8x8), index)
return watermarked_array
def test_init_custom_dimension(self):
image = MagicMock()
block_manager = BlocksImage(image, 4, 8)
self.assertEqual(block_manager.matrix, image)
self.assertEqual(block_manager.size_block_rows, 4)
self.assertEqual(block_manager.size_block_cols, 8)