Narrow Results

The improving technology and the ubiquity of the Internet have allowed more and more people to transmit data via the Internet. The contents of the transmission can be in the form of words, voices, images, or even computer animation. To protect the contents from interceptors' attention, the image hiding technology thus emerged. Some contents transmitted via the Internet can be confidential data such as highly valued product design blueprints or war plans, so it is important to pay more attention to the security of the transmitted data, or what we called secret image in this paper. The point of this paper is to enhance the security of the secret image without causing too much distortion to the host image and in the meantime to shorten the image hiding process time. For better protection, we adopted encryption process DES. In addition, we used greedy algorithm to shorten hiding process and to protect the host image from being severely distorted.

To test our proposed method to see whether it indeed achieved its objective, we used two sets of images in our experiment. The results of the experiments showed, when k = 2, our PSNR is close to that of Wang et al.'s optimal LSB substitution, but is not significantly different from that of simple LSB substitution. However, our method took approximately only 1/7 of the time consumed by Wang et al. When k = 3, our PSNR is significantly higher than that of simple LSB substitution. The experimental results confirmed that our method could effectively protect host image quality and shorten the overall hiding time when it enhanced the security of the secret image.

In this paper, a novel gray-level image-hiding scheme is proposed. The goal of this scheme is to hide multiple important gray-level images into another meaningful gray-level image. The secret images to be protected are first compressed using the vector quantization scheme. Then, the DES cryptosystem is conducted on the VQ indices and related parameters to generate the encrypted message. Finally, the encrypted message is embedded into the rightmost two bits of each pixel in the cover image.

According to the experimental results, average image qualities of 44.320 dB and 30.885 dB are achieved for the embedded images and the retrieved secret images, respectively. In other words, multiple secret images can be effectively hidden into one host image of the same size. In addition, the proposed scheme strengthens the protection of the secret images by conducting the DES cryptosystem on the related parameters and the VQ indices of the compressed secret images. Therefore, the proposed scheme provides a secure approach to embed multiple important images into another meaningful image of the same size.