| Summary: | 碩士 === 逢甲大學 === 資訊工程所 === 99 === As the Internet has developed rapidly and become more and more popular, it is quite common for people to transmit the data to others via Internet. However, the illegal attackers can easily intercept the data through the public Internet environment. Image hiding is one of the data security techniques to protect the secret data from illegal interception.
There are three classifications in image steganography: spatial domain, frequency domain, and the compressed domain. Spatial domain is the use of the image pixel value changes to achieve the purpose of data hiding, low computation and high capacity are advantages in Spatial domain.
Frequency domain sucked image converted to the frequency domain before data hiding, usually common conversion formula discrete fourier transform (DFT), discrete cosine transform (DCT), discrete wavelet transform (DWT), the nature of the image has a special feature, for example, robustness, fragility.. Compressed domain can not only compress image but also can be hide into the information, there is a common compression methods are Huffman compression, vector quantization compression.
There are two types in spatial domain: non-reversible data hiding and reversible data hiding. Non-reversible data hiding do not occur underflow or overflow problem in pixel value and no extra information, there are two representative methods, exploiting modification direction (EMD) and least significant bit (LSB) replacement. There are two famous methods in reversible data hiding, one is histogram base and other is difference expansion (DE) base, the advantage in reversible data hiding is that stego-image can be recover to original image.
In this thesis, two methods based module operation of non-reversible and reversible data hiding are proposed. The experimental results demonstrate that the proposed methods provide the higher embedding capacity than the compared methods and the satisfactory image quality of stego-image.
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