الفهرس 
chapter 1Only 14 pages are availabe for public view
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Abstract
Over the years, The Internet has become an effective tool in digital communication. At the same time, Data on the Internet has become susceptible to copyright infringement, piracy, etc. Therefore, secret communication has become an essential requirement. As a result, a new domain dedicated to information security has evolved and is known as data hiding. Steganography is one of the most common forms of data hiding. Steganography is the ability to pass information through original files such as images, video audio etc., in which existence of message is unknown. Although the embedded message changes the characteristics and nature of the original file, it is required that these changes are difficult to be identified by an unsuspecting user.
This thesis is an attempt to hide data into an image in frequency domain with high embedding capacity while preserving image quality and security against attacks. System was proposed and implemented using MATLAB technical computing language.
In the proposed method, the image is transformed into wavelet domain using the lifting integer wavelet transform technique. A hybrid edge detector combing Canny edge detector and Fuzzy edge detector is applied on low frequency sub-band to detect edges. This combination leads to increase the number of edge points. The edge information and the concept of set partitioning in hierarchal trees algorithm are used to define the edge/non-edge coefficients in the high frequency sub-bands. The secret data is embedded in the high frequency sub-bands’ coefficients using least significant bit substitution. As, the human eyes is less sensitive to changes in the edge regions, more bits are embedded in the edge coefficients than the non-edge ones. An optimal pixel adjustment process is preformed to minimize the error difference between original coefficients values and modified values.