Where am I wrong ? I want to create a basic white pict from bytes
from PIL import Image
if __name__ == "__main__":
data = [chr(1)] * 8192
data = "".join(data)
im = Image.frombytes('1', (128,64), data, 'raw')
im = im.convert("RGB")
im.save("image.png", "PNG")
But I get this:
Just use Image.new instead:
im = Image.new(mode='RGB', size=(128,64), color=(255,255,255))
If you really want to make it from bytes, it would be like this:
Image.frombytes(mode='RGB', size=(128,64), data=b'\xff'*128*64*3)
edit: Image.frombytes expects bytes, not a list of integers. To convert a list of integers to the right type, use this:
>>> bytes([0,1,2]) # Python 3
b'\x00\x01\x02'
>>> bytes(bytearray([0,1,2])) # Python 2
'\x00\x01\x02'
edit 2: mode='1' or the docs have bug (see comment thread). Assuming you have a list of zeros and ones, 1024 elements long, and you want to convert this to an 128x64 monochromatic image (one bit per pixel) then you'll have to pack the bytes manually:
bits = [int(not (y%13 and x%7)) for x in range(64) for y in range(128)]
# asymmetric grid
octets = [bits[i:i+8] for i in range(0, len(bits), 8)]
def bits2byte(bits8):
result = 0
for bit in bits8:
result <<= 1
result |= bit
return result
data = bytes(bytearray([bits2byte(octet) for octet in octets]))
im = Image.frombytes(mode='1', size=(128,64), data=data)
im.show()
Result:
In mode 1 each byte represents 8 pixels (there might be zero padding at end of each row if the width does not divide by 8). So to get a white image, you have to pass in only the byte b'\xff'
data = b'\xff' * 1024
im = Image.frombytes('1', (128,64), data)
Even if the Pillow docs say that there's one pixel per byte in this mode, that is not true for the frombytes and tobytes methods, at least.
Any other repeating input other than \xff (all white) or \x00 (all black) will give some sort of pinstripe pattern, like the one in your question.
Related
I'm trying to get lsb from the line of an image,I managed to get here:
from PIL import Image
import sys
challengeImg = Image.open('image.png')
pixels = challengeImg.load()
for x in range(2944):
red = (pixels[x,310][0])
bred = format(red,"b")
#print(green)
#print(bred)
green = (pixels[x,310][1])
bgreen = format(green,"b")
#print(bgreen)
#print(green)
Well, until then I'm fine but now my problem, I managed to create the following code:
num = 10100001
n = 0
lsb = num >> n &1
print(lsb)
It works, but only with one byte, I suppose that with for I can achieve something but I am very beginner and I have not managed to make it work, how I can do to extract the lsb from each byte in the line of pixels of the red channel (or green, I guess it's the same procedure)?
It occurs to me that I could use a dictionary to group the bits in bytes (1: 10011001, 2: 01100110 ...) and then use the loop to apply the lsb code in each byte, anyway I do not know how I can do this and i dont think it's the best way (maybe it's not even valid).
I have a .png image of 2944x1912 that contains information hidden in the least significant bits, the first code that I put is the script that I am developing, and so far what it does is get the information of the pixels of the red channel in the line 310 and transform them into binary.
The second code is the code to get the lsb of a byte which I need to implement in the first code, so the second code should somehow group all the bits in 8 and select the last one for I save in a variable, resulting in (2944/8 = 368 = 368 bytes.)
The solution that came to me might not be the most optimal. I'll look for a better solution if it does not suffice, but in the meanwhile:
num = 10100001
num_string = str(num)
lsb_string = num_string[len(num_string)-1]
lsb = int(lsb_string)
print(lsb)
# output: 1
It works, thats the code;
from PIL import Image
import sys
challengeImg = Image.open('challenge.png')
pixels = challengeImg.load()
for x in range(2944):
red = (pixels[x,310][0])
bred = format(red,"b")
#print(green)
#print(bred)
green = (pixels[x,310][1])
bgreen = format(green,"b")
#print(bgreen)
#print(green)
rnum = format(red,"b")
rnum_string = str(rnum)
rlsb_string = rnum_string[len(rnum_string)-1]
rlsb = int(rlsb_string)
print(rlsb, end="")
Thanks!
I am trying to read bytes from an image, and get all the int (16 bit) values from that image.
After I parsed the image header, I got to the pixel values. The values that I get when the pair of bytes are like b"\xd4\x00" is incorrect. In this case it should be 54272, not 3392.
This are parts of the code:
I use a generator to get the bytes:
import itertools
def osddef_generator(in_file):
with open(in_file, mode='rb') as f:
dat = f.read()
for byte in dat:
yield byte
def take_slice(in_generator, size):
return ''.join(str(chr(i)) for i in itertools.islice(in_generator, size))
def take_single_pixel(in_generator):
pix = itertools.islice(in_generator, 2)
hex_list = [hex(i) for i in pix]
hex_str = "".join(hex_list)[2:].replace("0x", '')
intval = int(hex_str, 16)
print("hex_list: ", hex_list)
print("hex_str: ", hex_str)
print("intval: ", intval)
After I get the header correctly using the take_slice method, I get to the part with the pixel values, where I use the take_single_pixel method.
Here, I get the bad results.
This is what I get:
hex_list: ['0xd4', '0x0']
hex_str: d40
intval: 3392
But the actual sequence of bytes that should be interpreted is: \xd4\x00, which equals to 54272, so that my hex_list = ['0xd4', '0x00'] and hex_str = d400.
Something happens when I have a sequence of bytes when the second one is \x00.
Got any ideas? Thanks!
There are much better ways of converting bytes to integters:
int.from_bytes() takes bytes input, and a byte order argument:
>>> int.from_bytes(b"\xd4\x00", 'big')
54272
>>> int.from_bytes(b"\xd4\x00", 'little')
212
The struct.unpack() function lets you convert a whole series of bytes to integers following a pattern:
>>> import struct
>>> struct.unpack('!4H', b'\xd4\x00\xd4\x00\xd4\x00\xd4\x00')
(54272, 54272, 54272, 54272)
The array module lets you read binary data representing homogenous integer data into a memory structure efficiently:
>>> array.array('H', fileobject)
However, array can't be told what byte order to use. You'd have to determine the current architecture byte order and call arr.byteswap() to reverse order if the machine order doesn't match the file order.
When reading image data, it is almost always preferable to use the struct module to do the parsing. You generally then use file.read() calls with specific sizes; if the header consists of 10 bytes, use:
headerinfo = struct.unpack('<expected header pattern for 10 bytes>', f.read(10))
and go from there. For examples, look at the Pillow / PIL image plugins source code; here is how the Blizzard Mipmap image format header is read:
def _read_blp_header(self):
self._blp_compression, = struct.unpack("<i", self.fp.read(4))
self._blp_encoding, = struct.unpack("<b", self.fp.read(1))
self._blp_alpha_depth, = struct.unpack("<b", self.fp.read(1))
self._blp_alpha_encoding, = struct.unpack("<b", self.fp.read(1))
self._blp_mips, = struct.unpack("<b", self.fp.read(1))
self._size = struct.unpack("<II", self.fp.read(8))
if self.magic == b"BLP1":
# Only present for BLP1
self._blp_encoding, = struct.unpack("<i", self.fp.read(4))
self._blp_subtype, = struct.unpack("<i", self.fp.read(4))
self._blp_offsets = struct.unpack("<16I", self.fp.read(16 * 4))
self._blp_lengths = struct.unpack("<16I", self.fp.read(16 * 4))
Because struct.unpack() always returns tuples, you can assign individual elements in a tuple to name1, name2, ... names on the left-hand size, including single_name, = assignments to extract a single result.
The separate set of read calls above could also be compressed into fewer calls:
comp, enc, adepth, aenc, mips, *size = struct.unpack("<i4b2I", self.fp.read(16))
if self.magic == b"BLP1":
# Only present for BLP1
enc, subtype = struct.unpack("<2i", self.fp.read(8))
followed by specific attribute assignments.
I have a bitmap image and using this page I am attempting to read the file size.
In case the link breaks:
FileSize | 4 bytes | File size in bytes
Here is part of the bitmap BM\xe6\x04\x00\x00\x00\x00\x00\x006 I want to read from, which as I understand it the file size is between the 3rd and 7th bytes. So \xe6\x04\x00\x00.
I remove all the \x00 since they are null values and don't tell me anything about the file size, so I used:
raw = '\xe6\x04\x00\x00'
character_list = [raw[b:b+1] for b in range(0, len(raw))]
non_empty = [list_ for list_ in character_list if list_ != b'\x00']
This returned me: [b'\xe6', b'\x04']
Now I get all the values in the list using:
size = ''
for byte in non_empty:
size += str(ord(byte))
print(size)
Here are the results of the conversion:
\xe6 > 230
\x04 > 4
This returns me 2304 (since '230' + '4' is 2304), while my bitmap image has the size of 1,254 bytes and 4,096 bytes on disk. Clearly this is not the image size. Where have I gone wrong?
As a side note. If I take another image of size 90 bytes and run the same process with Z\x00\x00\x00 it returns 90 as I expected. (ord('Z') returning 90).
From poking around it looks like the byte order for the size in a bitmap is little endian (https://en.wikipedia.org/wiki/Endianness#Little-endian).
There's a built-in method for int that can convert bytes to a integer. https://docs.python.org/3/library/stdtypes.html#int.from_bytes
So for example:
raw = b'\xe6\x04\x00\x00'
size = int.from_bytes(raw, byteorder='little')
print(size)
So my program is a Stenography program, it inserts an image into another image, and I'm trying to encrypt the data before inserting it into the cover image. However, most encryption modules expect strings and I'm trying to pass integers.
I've tried converting to string then encrypting, but the encryption is full of special characters and letters so converting back to integer for insertion is impossible.
Anyone know if I can somehow encrypt an integer? It doesn't have to be very secure.
I'm trying to add the encryption in here:
for i in range(0,3):
#verify we have reached the end of our hidden file
if count >= len(Stringbits):
#convert the bits to their rgb value and appened them
for rgbValue in pixelList:
pixelnumbers1 = int(''.join(str(b) for b in rgbValue), 2)
#print pixelnumbers1
rgb_Array.append(pixelnumbers1)
pixels[x, y] = (rgb_Array[0], rgb_Array[1], rgb_Array[2])
print "Completed"
return imageObject.save(output)
I've been trying to encrypt pixelnumbers1 then add it in. But pixels[x, y] requires an integer.
Below is the rest of the code in-case:
def write(mainimage, secret, output):
#string contains the header, data and length in binary
Stringbits = dcimage.createString(secret)
imageObject = Image.open(mainimage).convert('RGB')
imageWidth, imageHeight = imageObject.size
pixels = imageObject.load()
rgbDecimal_Array = []
rgb_Array = []
count = 0
#loop through each pixel
for x in range (imageWidth):
for y in range (imageHeight):
r,g,b = pixels[x,y]
#convert each pixel into an 8 bit representation
redPixel = list(bin(r)[2:].zfill(8))
greenPixel = list(bin(g)[2:].zfill(8))
bluePixel = list(bin(b)[2:].zfill(8))
pixelList = [redPixel, greenPixel, bluePixel]
#for each of rgb
for i in range(0,3):
#verify we have reached the end of our hidden file
if count >= len(Stringbits):
#convert the bits to their rgb value and appened them
for rgbValue in pixelList:
pixelnumbers1 = int(''.join(str(b) for b in rgbValue), 2)
#print pixelnumbers1
rgb_Array.append(pixelnumbers1)
pixels[x, y] = (rgb_Array[0], rgb_Array[1], rgb_Array[2])
print "Completed"
return imageObject.save(output)
#If we haven't rached the end of the file, store a bit
else:
pixelList[i][7] = Stringbits[count]
count+=1
pixels[x, y] = dcimage.getPixel(pixelList)
You have a fundamental misunderstanding of how computers see any type of data.
You read the bytestream of a file, which looks like a string to you, but each character is actually a byte, a value from 0 to 255. It just happens that some of them are represented by conventional string characters. Try print(bytes(range(256)) to see them all. Most standard encryption functions take a byte array in and spit a byte array out. It just happens that you get more of the bytes that don't have a "simple" representation. But they are not any less bytes than what you initially fed in.
Your dcimage.py has the following:
#get the file data in binary
fileData = bytearray(open(secret, 'rb').read())#opens the binary file in read or write mode
for bits in fileData:
binDataString += bin(bits)[2:].zfill(8)#convert the file data to binary
There is nothing that stops you from doing this
fileData = open(secret, 'rb').read() # a bytes object by default
encryptedData = myEncryptionFuction(fileData) # also a bytes object
for bits in encryptedData:
# ...
VERY IMPORTANT: You add a null byte at the end of your message so your extracting sequence knows when to stop. If you compress, or encrypt, a string (or byte array), it is likely a null byte will be part of that stream, which will break your extraction sequence. In that case you want to use a header that tells your program ahead of time how many bits to extract.
By the way, bytes are already in an integer form.
>>> some_byte = b'G'
>>> some_byte[0]
71
You're better of using bitwise operations for steganography. You take bytes and instead of using bitwise operations between them and your pixels, you turn both to binary strings, slice and stitch them and then turn them back to integers.
def bytes_to_bits(stream):
for byte in stream:
for shift in range(7, -1, -1):
yield (byte >> shift) & 0x01
secret_bits = tuple(bytes_to_bits(encoded_data))
# simplified for one colour plane
for x in range(image_height):
for y in range(image_width):
# (pixel AND 254) OR bit - the first part zeroes out the lsb
pixels[x,y] = (pixels[x,y] & 0xfe) | secret_bits[count]
count += 1
# -------------------------------------
# to extract the bit from a stego pixel
bit = pixel & 0x01
Integers can be encryted by adding each digit to a random integer stream in the range 0 to 9, subtracting 10 when the sum > 9. Modulo should be avoided because of ambiguities.
I have a Client that recieves an image from a TCP Server in a TCP Client.
After this the Image is serialized and of course as bytes. Now I want to to reshape this again into an image.
However my process takes really long so I was wondering if there is maybe a more pythonic,faster way of doing so ?
The code is commented for each step, but here they are:
1.Convert it from hex binary representation to a readable string (0.002 s)
2.Split up the string after each byte couple (0.08 s)
3.Cast each value of the list to integer (0.17 s)
4.Reshape into matrix representation for red,green,blue (0.02)
5.Reshape Matrices together to form image
After looking at timings I found out that the most time is taking by step 3.
#....Some TCP stuff before, and this code is in a loop:
#Convert from hex binary to string
asstr = binascii.hexlify(data)
#Split up after each byte couple
n = 2
split = [asstr[i:i+n] for i in range(0, len(asstr), n)]
#Convert each byte couple to integer from its hex representation
asint = [];
for i in split:
asint.append(int(i,16))
#Reshape into red,green and blue
try:
red = np.asarray(asint[::3]).reshape(240,424);
green = np.asarray(asint[1::3]).reshape(240,424);
blue = np.asarray(asint[2::3]).reshape(240,424);
except ValueError:
continue;
#Reshape into an Image representation for opencv
img = np.transpose(np.asarray([red,green,blue],dtype=np.uint8),axes=(1, 2, 0))
#Show image
cv2.imshow('something',img)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
If I print out data I get some "ascii-crap" in the command line which are just representations of their numbers in ascii.
After decoding them with binascci.hexlify(data) and printing it out I get the values as one huge string like "0112311a3b2b1c312..." (just an example)
Are you sure you are not making things way more complicated than necessary? Maybe I'm missing something, but with a mock bytes object of the correct length I get the same output as your five-step method in a single line:
import numpy as np
import binascii
def the_humourless_route(data):
return np.frombuffer(data, dtype=np.uint8).reshape(240, 424, 3)
def the_scenic_route(data):
#....Some TCP stuff before, and this code is in a loop:
#Convert from hex binary to string
asstr = binascii.hexlify(data)
#Split up after each byte couple
n = 2
split = [asstr[i:i+n] for i in range(0, len(asstr), n)]
#Convert each byte couple to integer from its hex representation
asint = [];
for i in split:
asint.append(int(i,16))
#Reshape into red,green and blue
try:
red = np.asarray(asint[::3]).reshape(240,424);
green = np.asarray(asint[1::3]).reshape(240,424);
blue = np.asarray(asint[2::3]).reshape(240,424);
except ValueError:
pass
#Reshape into an Image representation for opencv
img = np.transpose(np.asarray([red,green,blue],dtype=np.uint8),axes=(1, 2, 0))
return img
data = bytes(np.random.randint(0, 256, (240*424*3,)).tolist())
print(np.all(the_scenic_route(data) == the_humourless_route(data)))
Output:
True