A simple proof of concept to show how to hide data into images.
Image capsule uses even or odd numbers to determine if a bit is 1 or 0. First it takes the binary data of the source file and adds a header to it which defines how long the data is.
Then it converts the binary data into even or odd pixel numbers.
It would be also possible to use the color values R G B to store three times more data into an image.
For example I took the Lena image and inserted the camera man image into it.
Lena Original
Possible Data Length: 32764 bytes
Camera Man
Data Length: 16119 bytes
You can see the difference of the original image and the image which contains the data.
Lena Difference
Written on a hacky evening!