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Improvements of the hide and reveal method (limit of the message to hide).

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cedricbonhomme 2011-03-23 22:45:40 +01:00
parent 4e7800cea8
commit 707e69a274
1 changed files with 23 additions and 5 deletions
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28
lsb-s.py
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@ -20,8 +20,8 @@
# along with this program. If not, see <http://www.gnu.org/licenses/> # along with this program. If not, see <http://www.gnu.org/licenses/>
__author__ = "Cedric Bonhomme" __author__ = "Cedric Bonhomme"
__version__ = "$Revision: 0.1 $" __version__ = "$Revision: 0.2 $"
__date__ = "$Date: 2010/10/01 $" __date__ = "$Date: 2010/03/23 $"
__license__ = "GPLv3" __license__ = "GPLv3"
import sys import sys
@ -39,7 +39,7 @@ def hide(img, message):
width, height = img.size width, height = img.size
index = 0 index = 0
message = message + '~~~' message = str(len(message)) + ":" + message
#message_bits = tools.a2bits(message) #message_bits = tools.a2bits(message)
message_bits = "".join(tools.a2bits_list(message)) message_bits = "".join(tools.a2bits_list(message))
@ -75,6 +75,7 @@ def reveal(img):
width, height = img.size width, height = img.size
buff, count = 0, 0 buff, count = 0, 0
bitab = [] bitab = []
limit = None
for row in xrange(height): for row in xrange(height):
for col in xrange(width): for col in xrange(width):
r, g, b = img.getpixel((col, row)) r, g, b = img.getpixel((col, row))
@ -84,21 +85,38 @@ def reveal(img):
if count == 8: if count == 8:
bitab.append(chr(buff)) bitab.append(chr(buff))
buff, count = 0, 0 buff, count = 0, 0
if bitab[-1] == ":" and limit == None:
try:
limit = int("".join(bitab[:-1]))
except:
pass
buff += (g&1)<<(7-count) buff += (g&1)<<(7-count)
count += 1 count += 1
if count == 8: if count == 8:
bitab.append(chr(buff)) bitab.append(chr(buff))
buff, count = 0, 0 buff, count = 0, 0
if bitab[-1] == ":" and limit == None:
try:
limit = int("".join(bitab[:-1]))
except:
pass
buff += (b&1)<<(7-count) buff += (b&1)<<(7-count)
count += 1 count += 1
if count == 8: if count == 8:
bitab.append(chr(buff)) bitab.append(chr(buff))
buff, count = 0, 0 buff, count = 0, 0
if bitab[-1] == ":" and limit == None:
try:
limit = int("".join(bitab[:-1]))
except:
pass
if len(bitab) > 0 and bitab[-1] == chr(126):
return "".join(bitab)[:-1] if len(bitab)-len(str(limit))-1 == limit :
return "".join(bitab)[len(str(limit))+1:]
return "" return ""
def reveal_slow(img): def reveal_slow(img):