Secret Image Hiding and Sharing Based on the (t, n)-Threshold

題名: Secret Image Hiding and Sharing Based on the (t, n)-Threshold 作者: Chang, C. C.;Lin, C. Y.;Tseng, C. S.

關鍵詞: Secret image sharing;steganography;image quantization;(t,n)-threshold secret sharing

日期: 2007-04

上傳時間: 2009-12-17T06:58:06Z 出版者: Asia University

摘要: This study proposes a new secret image sharing method based on the (t,n)-threshold. The sharing method is completed through three main steps: (1) quantizing the secret image, (2) generating n shadows from

the quantized image, and (3) sharing the n shadows among n cover images. Our goal is both to attain good stego-image and secret image quality preservation effects and to limit the size of each shadow image down to 1/t of that of the secret image for convenient transmission and storage. In the first step, the secret image is divided into non-

overlapping 4 ? 4 blocks that are quantized according to the results of block testing. Each block, after the block testing procedure, is judged to be either a smooth block or a non-smooth one. Smooth blocks can be neatly restored after being hidden into the cover image, while non- smooth blocks can be somewhat lossy, but such modification is perceptually invisible. The second step is to apply Shamir's (t,n)-

threshold, which uses a (t?1)-degree polynomial to generate n shadows so that the secret image can be restored from any t out of n shadows.

The last step involves a modulo operation to hide the n shadows in n cover images. According to our experimental results, the PSNR values of the reconstructed secret images by our method center around 39 dB, outperforming other recent methods.