11-05-2012, 05:23 PM
IMAGE PROCESSING-STEGANOGRAPHY
STEGANOGRAPHY.doc (Size: 1.03 MB / Downloads: 118)
ABSTRACT:
In the present world Computer Graphics plays an important role. The areas here we are using computer graphics are Entertainment, Presentations, Education and training, Visualization, Design, Image Processing and Graphical User Interface. In all these Image Processing has its own importance.
Image Processing deals with how we can improve the clarity of image and to manipulate the image which is a very important application of computer graphics. In Image processing we are doing some operation on image. This paper mainly concentrates on what is an image and how processing takes place, digital image.
INTRODUCTION:
Modern digital technology has made it possible to manipulate multi-dimensional Signals with systems that range from simple digital circuits to advanced parallel computers. The goal of this manipulation can be divided into three categories:
• Image Processing image in ->image out
• Image Analysis image in ->measurements out
• Image Understanding image in ->high-level description out
Here in this paper we deal with the secret transformation of information through images.
What is meant by steganography?
If you have some secret data, you should encrypt it to make it unreadable for the third party.
Data encryption is a solution to keep secret information very safe. It is based on data scrambling by using some type of secret key.however data encrypting will much more attention of the people than not encrypting it. So the owner of the encrypted data will be easily known that he\she is hiding something. Therefore encrypting is enough.
There is another solution which is called steganography.
In steganography you will two types of data.
1. One is the secret data itself that is very valuable to you.
2. the other one is a type of media data called “vessel”,”carrier”,or”dummy” data.
Such vessel data is essential but not so valuable. It is the data in which the valuable data is “embedded”. An “already embedded” vessel data is called “stego data”. When you want to recover the valuable (or secret) data, you can extract it from the stego data. For both embedding and extracting you need a special program and key. Here a losses data hiding method using IWT and BPCS, in which image data are decomposed by IWT and each bit plane of the sub-bands segmented in 8x8 blocks. All blocks are analyzed by complexity measures to determine which blocks are analyzed by complexity measurement used in the proposed system is same one in the BPCS method.
Internet communication has become an integral part of the infrastructure of today’s world. The information communicated comes in numerous forms and is used in many applications. In a large number of these applications, it is desired that the communication be done in secrete. Such secret communication ranges from the obvious cases of bank transfers, corporate communications, and credit card purchases, on down to a large percentage of everyday email. With email, many people wrongly assume that their communication is safe because it is just a small piece of an enormous amount of data being sent worldwide. After all, who is going to see it? But in reality, the Internet is not a secure medium, and there are programs “out there” which just sit and watch messages go by for interesting information.
Encryption provides an obvious approach to information security, and encryption programs are readily available. However, encryption clearly marks a message as containing “interesting” information, and the encrypted message becomes subject to attack. Furthermore, in many cases it is desirable to send information without anyone even noticing that information has been sent.
Steganography presents another approach to information security. In steganography, data is hidden inside a vessel or container that looks like it contains only something else. A variety of vessels are possible, such as digital images, sound clips, and even executable files. In recent years, several steganographic programs have been posted on Internet home pages. Most of them use image data for the container of the secret information. Some of them use the least significant bits of the image data to hide the data. Other programs embed the secret information in a specific band of the spatial frequency component of the carrier. Some other programs make use of the sampling error in image digitization. However, all those steganographic techniques are limited in terms of information hiding capacity. They can embed only 5-15 % of the vessel image at the best. Therefore, current steganography is more oriented to water marking of computer data than to secret person-person communication applications. We have invented a new technique to hide secret information in a color image. This is not based on a programming technique, but is based on the property of human vision system. Its information hiding capacity can be as large as 50% of the original image data. This could open new applications for steganography leading to a more secure Internet communication age.
If you have some secret data, you should encrypt it to make it unreadable for the third party. Data encryption is a solution to keep secret information very safe. It is based on data scrambling by using some type of secret key.
However, data encrypting will draw much more attention of the near-by people than not encrypting it. So, the owner of the encrypted data will be easily known that he/she is hiding something. Therefore, encrypting is not enough.
There is another solution which is called steganography. Steganography today is like the following.
In steganography you will have two types of data. One is the secret data itself that is very valuable to you. The other one is a type of media data called "vessel", "carrier", or "dummy" data. Such vessel data is essential, but is not so valuable. It is the data in which the valuable data is "embedded." An "already embedded" vessel data is called "stego data." When you want to recover the valuable (or secret) data, you can "extract" it from the stego data. For both embedding and extracting you need a special program and a key.
A typical vessel is an image data with Red, Green, and Blue color components in a 24 bits pixel structure. The illustration below shows a general scheme of steganography.
Steganography is a technique to hide secret data by embedding it in some innocent looking media data like Mona Lisa here. The embedded data is very safe because steganography hide both the content and the location of the secret information. There are many different methods to embed data in the media data. It is impossible to detect which method is used for embedding. Steganography can co-operate with cryptography in the sense that it can embed the encrypted secret data to make it much safer.
The most important point in steganography is that the stego data does not have any evidence that some extra data is embedded there. In other words, the vessel data and the stego data must be very similar. A user of steganography should discard the original vessel data after embedding in order not to allow anyone to compare the stego and the original data.
It is also important that the embedding capacity is large. The larger the better. For image steganography we are confident that BPCS method is the best of all currently available steganographic methods.