Image Steganography whole details

Hello Slateers, in this  slate we are going to know about an interesting technique related to hiding sensitive information from the eyes  of data – thieves. World calls it ‘Steganography’ and in this slate, we discuss something related to steganography, and image steganography in particular. ‘Steganography’ do exist even from the earlier eras, but forms of steganography have been modified and now the field is diversified and potential.

Image Steganography


            In this 21st century digital world, norms of privacy and ownership have been posing a challenge. Developers are in search of new ways of providing anonymity to the users of their products. In this regard, several innovative methods of data hiding have come into existence. One of such methods is Steganography, which has the unique property of providing both security and ownership.


            Steganography is the art of concealing the sensitive information in one of the widely used binary data objects such as image, audio, text and video etc., in both perceptual and statistical manners. It differs from traditional cryptography, which is used to make the information indecipherable thus preventing eavesdropping but doesn’t veil the presence of surreptitious communication. At this juncture, steganography comes into picture because of its stealthy nature based on few principles of cryptography. Besides covert communication, Steganography plays laudable role in ownership, authentication and copyright related issues of digital images.

It also helps in checking data integrity and spotting counterfeits. Early steganography included cipher-texting, pinpricks in maps, and tattoos on scalp etc., Image steganography refers to steganography using images as cover objects. Images are stored as array of numbers representing values of RGB parameters for each image element called pixel. Usually, each pixel is encoded in 24 bits (1 byte for each RGB parameter) and this color encoding determines the file size. An image of 1280 X 720 dimensions with 8 bit/pixel color encoding has a size of 1280 X 720(=9,21,600 bytes) while the image with same dimensions and 24 bit/pixel color encoding has a size of 1280 X 720 X 3 (=27,64,800 bytes). While we are using steganography, we must bear in mind the following criteria:

While using steganography must remember criteria:

♦   Cover objects must not be varied up to an extent of perception of the secret message.

♦   The embedded secret message must be immune to cover object’s modification.

♦   Error correcting codes must be provided to protect the embedded message from any modifications.

Typical Example: Using ‘Quick Stego’* tool,  A product of ‘cybernescence software solutions’[]

Message to be hidden: “This is hidden text”

Image steganography original image

original image

steganography  image with hidden message

steganographe image

Several methods of implementing image steganography are as follows:

Substitution methods:

♦   Bit plane techniques

♦   Palette manipulation techniques

Signal processing methods:

♦   Transform technique

Other Coding methods:

♦   Quantizing, Dithering

♦   Error correction codes

We discuss the above methods in brief.

Substitution methods:

Message is embedded in the noise of images.

Bit plane techniques:

It refers to replacing least significant bit of pixels with our sensitive data such that the data is not perceivable. Variations include permutation of the selection of the pixels that are embedded with the data, using hash key etc.,

Also ReadA new trend to 3D: Holographic Displays

Palette manipulation technique:

It refers to changing the way the color or gray scale palette represent the image colors. We prefer using gray scale images in preventing the problem of color shift that gives the hint showing hidden text.

 Signal Processing methods:

 Message is embedded in the signal.

Transform technique:

We use different types of functions such as discrete cosine/wavelet/fourier/mellin-fourier transforms to compress the image and then hide the message.

As everything has a contrary one, steganalysis works as the inverse of steganography, which tries to search for any hidden messages in the data objects. Steganography might appear to be come handy for general purposes, but combined with cryptography, it would act as a smart indispensable technique for security purposes, privacy protection and other copyright related issues.

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