الفهرس 
acknowledgmentOnly 14 pages are availabe for public view
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Abstract
Although the use steganography began many centuries ago, this field recently became an important area of interest for individuals, corporations, and governments... Steganographic technologies are a very important part of the future for the following reasons:- It is difficult to discover the stego files because stego files are not only send by emails but these file are found on the web sites ,no one know the stego file except the authenticated person , because The steganography uses digital images Steganography is very useful for big companies, militaries purposes and in the non-commercial sector to
hide information that someone wants to keep private. - In Steganography there are two files, the original file and the stego file, this reason cancels any risk to delete or lost data. - It’s very difficult to discover the stego image within the
million of JPEG images in the web and in digital cameras. There are many differences between steganography and watermark, steganography hides information in images and its unknown to the user but water mark encrypts the data, the ability to hide both raw data and encrypted data. Now there are many steganography techniques is discovered but steganography in JPEG images faces many problems .These problems are then chariges in the original images .these changes enables the users to know easily the difference between the original image and the stego .The changes in JPEG images are in image colors and the stego file size .The stego image size is more bigger than original image or The size of stego image is more and more smaller than original image. There also many stego tools and algorithms. The best widely known steganography algorithm is based on modifying the least significant bit layer of images, hence known as the LSB technique but also this algorithm and LSB technique increase the size of stego image also this technique has a limit capacity of stego data. This study selects JPG file format for steganography because of the following reasons:- JPG format is very complex so most programmers don’t do steganography programs for JPG because lossy compression causes lost of data.- JPEG uses High (24 bits/pixel 16 million colors) true color so JPEG contain more spaces these images provide more space for hiding information GIF, the other image format widely used oif the net, can only store 8 bits/pixel (256 or fewer colors) JPEG is far more useful than GIF for exchanging images among
people with widely varying display hardware, because it avoids prejudging how many colors to use.