What is Image stegnography

Image steganography is simply a data hiding technique while sub part of Steganography.
Commonly there are two data hiding techniques.

1. Steganography
2. Cryptography

In the Cryptography everyone knows there are hidden data in the data or information.
E.g. Serial key or activation key, which is used to hide important number is made by cryptography.

But in the steganography anyone doesn’t know there are hidden messages in the data file.
There are various types of steganography techniques.
Such as
Image Steganography – Cover image used to hide data
Audio Steganography – Cover audio file is used to hide data
Video Steganography – Cover video file is used to hide data
Text Steganography – Cover text file is used to hide data

In this post I’m going to give my attention only for image Steganography. In image Steganography we are using Cover image for hide data. In the cover image we hide our secret data so everyone sees only the cover image but do not show any hint there are hidden data in the image. We can hide any type of data in a image.

Image consist of many amount of pixels with various intensity values
e.g. RGB image consists of 3 different color intensities for store color data in the image
R- RED
G- GREEN
B-BLUE

Black and white image
Black – 0
White – 1

There are many image compression types. Some are lossless while some are loosely.
Lossless – GIF, PNG,
Loosely – GPEG

Lossless image compression can simply use for image steganography by applying common algorithm known as “substitution of least significant bit.”. But images with loosely image compression cannot simply used for image steganography but can use more advanced methods such as Discrete cosine algorithms.