def decode(stego_image, key_file):
"""
Decodes the stego image based on valid key_file.
"""
f = open(key_file, 'rb')
tup = pickle.load(f)
f.close()
angles, block_size, key, rev_angles = tup
# divide the stego image into same block size again
new_width, new_height, width, height, new_inv_dir = split_blocks(
stego_image, block_size)
# change to the invisible directory.
cwd = os.getcwd()
os.chdir(new_inv_dir)
# find all the images.
l = os.listdir(os.getcwd())
# arrange them in increasing order.
k = []
counter = 1
while counter != len(l) + 1:
k.append(str(counter) + '.png')
counter += 1
for block in range(len(k)):
# open the image = k[block]
I = Image.open(k[block]).convert('RGBA')
# rotate the image by reverse angle generated above.
I = I.rotate(angles[block])
I.save(k[block])
merge_images.merge_folder(os.getcwd(), block_size, new_width, new_height)
# apply lsb_matching expose method.
print('Decoding initiated...')
key = key.split(' ')[1]
msg = lsb_matching.expose_message('final.final.png', int(key))
# remove .final folder. Of no use.
tempfolder = os.getcwd()
os.chdir(cwd)
shutil.rmtree(tempfolder)
return msg
def step1(image, block_size=5, dont_delete=False):
# call the split_blocks function to split image into blocks.
print("Splitting image")
new_width, new_height, width, height, invisible_dir = split_blocks(image, block_size)
# change to the invisible directory.
cwd = os.getcwd()
os.chdir(invisible_dir)
# find all the images.
l = os.listdir(os.getcwd())
# arrange them in increasing order.
k = []
counter = 1
while counter != len(l)+1:
k.append(str(counter)+'.png')
counter += 1
# now k contains all the images in increasing order.
# radomly rotate them.
angles = []
print("Rotating blocks")
for i in k:
angles.append(random_angle_rotations(i))
# now merge the rotated images.
print("Joining rotated blocks")
merge_images.merge_folder(os.getcwd(), block_size, new_width, new_height)
# find the main directory.
mainDir = os.path.dirname(image)
# get image name only, without extension
image_name = os.path.basename(image).split('.')[0]
# move the generated image to mainDir.
tempfolder = os.getcwd()
os.rename(os.path.join(tempfolder, 'final.'+image_name+'.png'), os.path.join(mainDir, 'final.'+image_name+'.png'))
# temporary folder is of no use now. Delete it!
os.chdir(cwd)
if not dont_delete:
shutil.rmtree(tempfolder)
return angles
def pixelate(image, message, block_size=5, dont_delete=False):
# call the split_blocks function to split image into blocks.
print("Splitting image")
new_width, new_height, width, height, invisible_dir = split_blocks(
image, block_size)
# change to the invisible directory.
cwd = os.getcwd()
os.chdir(invisible_dir)
# find all the images.
l = os.listdir(os.getcwd())
# arrange them in increasing order.
k = []
counter = 1
while counter != len(l) + 1:
k.append(str(counter) + '.png')
counter += 1
# now k contains all the images in increasing order.
# radomly rotate them.
angles = []
print("Rotating blocks")
for i in k:
angles.append(random_angle_rotations(i))
# now merge the rotated images.
print("Joining rotated blocks")
merge_images.merge_folder(os.getcwd(), block_size, new_width, new_height)
# find the main directory.
mainDir = os.path.dirname(image)
# get image name only, without extension
image_name = os.path.basename(image).split('.')[0]
# move the generated image to mainDir.
tempfolder = os.getcwd()
os.rename(os.path.join(tempfolder, 'final.' + image_name + '.png'),
os.path.join(mainDir, 'final.' + image_name + '.png'))
# temporary folder is of no use now. Delete it!
os.chdir(cwd)
if not dont_delete:
shutil.rmtree(tempfolder)
# raster scan the scrumbled image which is stored in the mainDir.
os.chdir(mainDir)
# open the scrumbled image. raster_scan() internally converts to grayscale.
scrumbled_image = Image.open('final.' + image_name + '.png')
scrumbled_image_name = 'final.' + image_name + '.png'
# start the procedure of LSB Replacement
key = lsb_matching.image_embedding(scrumbled_image_name, message,
'final.' + image_name + '-stego.png')
print(key)
# ----------------------------------------------------------------------------------------------------#
# divide the stego image into same block size again
new_width, new_height, width, height, new_inv_dir = split_blocks(
'final.' + image_name + '-stego.png', block_size)
rev_angles = (-1 * np.array(angles)).tolist()
# change to the invisible directory.
cwd = os.getcwd()
os.chdir(new_inv_dir)
# find all the images.
l = os.listdir(os.getcwd())
# arrange them in increasing order.
k = []
counter = 1
while counter != len(l) + 1:
k.append(str(counter) + '.png')
counter += 1
for block in range(len(k)):
# open the image = k[block]
I = Image.open(k[block]).convert('RGBA')
# rotate the image by reverse angle generated above.
I = I.rotate(rev_angles[block])
I.save(k[block])
merge_images.merge_folder(os.getcwd(), block_size, new_width, new_height)
# get image name only, without extension
image_name = os.path.basename(image).split('.')[0]
# move the generated image to mainDir.
tempfolder = os.getcwd()
os.rename(os.path.join(tempfolder, 'final.final.png'),
os.path.join(mainDir, 'final.final.png'))
# temporary folder is of no use now. Delete it!
os.chdir(cwd)
if not dont_delete:
shutil.rmtree(tempfolder)
# ----------------------------------------------------------------------------------------------------- #
tup = angles, block_size, key, rev_angles
# save this tuple in a file.
f = open(scrumbled_image_name + '.dat', 'wb')
pickle.dump(tup, f)
f.close()
os.chdir(cwd)
os.remove('final.' + image_name + '.png')
os.remove('final.' + image_name + '-stego.png')
return 1
def step1(image, block_size=5, dont_delete=False):
# call the split_blocks function to split image into blocks.
print("Splitting image")
new_width, new_height, width, height, invisible_dir = split_blocks(
image, block_size)
# change to the invisible directory.
cwd = os.getcwd()
os.chdir(invisible_dir)
# find all the images.
l = os.listdir(os.getcwd())
# arrange them in increasing order.
k = []
counter = 1
while counter != len(l) + 1:
k.append(str(counter) + '.png')
counter += 1
# now k contains all the images in increasing order.
# radomly rotate them.
angles = []
print("Rotating blocks")
for i in k:
angles.append(random_angle_rotations(i))
# now merge the rotated images.
print("Joining rotated blocks")
merge_images.merge_folder(os.getcwd(), block_size, new_width, new_height)
# find the main directory.
mainDir = os.path.dirname(image)
# get image name only, without extension
image_name = os.path.basename(image).split('.')[0]
# move the generated image to mainDir.
tempfolder = os.getcwd()
os.rename(os.path.join(tempfolder, 'final.' + image_name + '.png'),
os.path.join(mainDir, 'final.' + image_name + '.png'))
# temporary folder is of no use now. Delete it!
os.chdir(cwd)
if not dont_delete:
shutil.rmtree(tempfolder)
# raster scan the scrumbled image which is stored in the mainDir.
os.chdir(mainDir)
# open the scrumbled image. raster_scan() internally converts to grayscale.
scrumbled_image = Image.open('final.' + image_name + '.png')
scrumbled_image = raster_scan(scrumbled_image)
# iterate in consecutive_difference to find the pixels variations greater than threshold parameter 't'.
t = 15
# group the pixels in the pair of 2.
new_image = list(zip(scrumbled_image[::2], scrumbled_image[1::2]))
new_image = np.array(new_image)
# select those pairs where difference is greater than 't'.
EU = new_image[np.abs(new_image[:, 0].astype(int) -
new_image[:, 1].astype(int)) >= t]
print(EU)
return angles