The Input Image shown on the left is the original, unedited source image. The Output Image shown on the right has some text hidden within it.
Data that makes up the text "The Hobbit" by J.R.R. Tolkien is hidden within the Output Image - specifically, distributed across the least-significant bits of each pixel. The extracted text is shown below. The point here is that the images are (to the eye) indistinguishable, yet an enormous amount of information may be concealed. Raw text for The Hobbit is from archive.org