الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
Information hiding is accomplished through hiding secret information in public information. Secret information can be embedded inside a piece of unsuspicious information and transmitted without noticing the existence of the transmitted information. In image data hiding, the secret image is hidden exclusively in an image which is called the cover image. After embedding the secret image, the cover image is called the stego-image. To be a useful image data hiding system, it must provide a method to embed the secret image imperceptibly, and the extracted secret image must be able to convey the meaning after extraction.
This thesis provides a new wavelet-based image data hiding technique for hiding a secret image S inside a cover image C using two secret keys to establish a stego-image G, without drawing any suspicion to the transmission of the secret image. We are concerned with image data hiding as with the development of internet and multimedia techniques, digital information can be transmitted conveniently over the network. Therefore image data hiding algorithms, used to protect secret images during transmission, become an important issue. The proposed technique shows high robustness against many of image processing operations such as lossy compression, blurring, cropping, median filter, sharpening, and addition of noise. The embedded secret image can be extracted with high visual quality. The stego-image is looking perfectly intact and has high peak signal to noise ratio (PSNR). By using the proposed embedding process, the PSNR of the stego-image is about 52.17 dB for secret image of size (256x256) hidden in a cover image of size (512x512), and about 40.28 dB for secret image of the same size (512x512) as the cover image. The proposed technique does not require the original cover image to extract the embedded secret image. The comparative analysis between the proposed technique and the other existing techniques has shown the superiority of the proposed technique.
The proposed grey-scale image data hiding technique is straightforwardly extended to color images by applying it to each color component individually. The computer simulation results are not like those in the case of grey-scale images but they are good.