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The same image viewed by white, blue, green, and red lights reveals different hidden numbers. Steganography (/ ˌ s t ɛ ɡ ə ˈ n ɒ ɡ r ə f i / ⓘ STEG-ə-NOG-rə-fee) is the practice of representing information within another message or physical object, in such a manner that the presence of the concealed information would not be evident to an unsuspecting person's examination.
Image of a tree with a steganographically hidden image. The hidden image is revealed by removing all but the two least significant bits of each color component and a subsequent normalization. The hidden image is shown below. Image of a cat extracted from the tree image above. Concealing messages within the lowest bits of noisy images or sound ...
The problem is generally handled with statistical analysis. A set of unmodified files of the same type, and ideally from the same source (for example, the same model of digital camera, or if possible, the same digital camera; digital audio from a CD MP3 files have been "ripped" from; etc.) as the set being inspected, are analyzed for various statistics.
Steganography architecture example - OpenPuff A steganography software tool allows a user to embed hidden data inside a carrier file, such as an image or video, and later extract that data. It is not necessary to conceal the message in the original file at all.
An algorithm estimates the capacity for hidden data without the distortions of the decoy data becoming apparent. OutGuess determines bits in the decoy data that it considers most expendable and then distributes secret bits based on a shared secret in a pseudorandom pattern across these redundant bits, flipping some of them according to the secret data.
It just marks data, but does not degrade it or control access to the data. One application of digital watermarking is source tracking. A watermark is embedded into a digital signal at each point of distribution. If a copy of the work is found later, then the watermark may be retrieved from the copy and the source of the distribution is known.
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First, an initial reduced negative was made, then the image of the negative was projected from the eyepiece of a modified microscope onto a collodium emulsion where the microscope specimen slide would be. The reduction was such that a page of text would be legibly reproduced in an area of 0.01 mm 2. This density is comparable to the entire text ...