Image Steganography is the process of hiding information which can be text, image or video inside a cover image. The secret information is hidden in a way that it not visible to the human eyes.
The intention is to hide any kind of data (in this demonstration we are using text) in a picture using the fact that a phot is only an interpretation of pixels (3-value type of data)
Suppose that the message we want to hide is "Hello", since the message made of 5 byte, the pixels required for the encoding are 3·5=15, so a 4x4 image will be good to hide that kind of information
H = 72 = 01001000
e = 101 = 01100101
l = 108 = 01101100
o = 111 = 01101111
Now take a random 4x3 image made like this (total of 12 pixels):
[(86,23,54),(12,53,85),(132,22,210),(61,19,249),
(60,81,40),(37,195,64),(191,129,188),(151,130,63),
(120,3,92),(219,175,215),(132,102,101),(146,248,141),
(107,230,44),(224,120,196),(160,228,212),(94,215,135)]
Now, to encode the message pick the binary encoding of the letter and if the number is 1 change the number to odd, if its a 0 change the number to an even Let's make an example with the H:
- Take the binary in group of the letter ('H' in this case):
01001000 - Pick the first 3 pixels of the image:
(86,23,54),(12,53,85),(132,22,210) - Create the new pixels with the method descripted:
(86,23,54),(12,53,84),(132,22,210)
Do the same thing for all the letter
[(86,23,54),(12,53,84),(132,22,210),(61,19,248),
(60,81,40),(37,194,63),(191,128,187),(151,130,62),
(120,3,91),(218,175,215),(132,102,100),(145,247,140),
(107,229,43),(223,120,196),(160,228,212),(94,215,135)]
When the image is put in the decoder, it will controll every pixel, if the number is odd then it's a 1, if it's even a 0, then all will be reconverted from binary to normal text
