This projects hides a text in a given image. Hiding a given text in an image is called Steganography. There are many ways to accomplish this task, one of which is presented in this project. The project starts from reading an image, using pyplot. Note that a colored image is a three dimensional array, which is composed of three 2-D arrays (r, g and b). The next step converts the image into grayscale using the to_gray method. Note that the converted image is a 2-D image and has values between 0 and 255. Now, we will ask the user to enter a text and store it in a variable called Text. The further action of course is slightly involved. It requires the following
- For each word in the text, each character in the word is converted into ASCII value. The key (shared by the sender and the receiver) is then added to the ASCII value. The final number is appended to a list.
- Flattening the image: The two dimensional image is converted into a one dimensional image, using the reshape method of numpy.
- Now, random numbers (equal to the number of elements in the list created in the previous step) are generated (Positions) and the corresponding values in the flattened image is replaced by the elements of the list.
- The array so formed is again converted into original shape.
- The Positions array and the image obtained in the previous step are sent to the receiver.
- At the receiver’s side, the received image is flattened.
- At the locations indicated by the Positions, each value of replaced by the difference of the value and the key. The integers so obtained are converted to characters and appended to the decoded text.