Abstract
Currently, the watermark capacity of most self-recovery fragile image watermarking schemes is fixed. That means for smooth regions and texture regions, the length of watermark information is always the same. However, it is impractical since more recovery information is needed for the recovery of texture regions. In this paper, a self-recovery fragile image watermarking with variable watermark capacity is proposed. Based on the characteristic of singular value decomposition (SVD), a new block classification method is introduced. The image blocks are classified into smooth blocks and texture blocks. For smooth blocks, the average pixel values are adopted as the recovery information to recover the tampered blocks, while for texture blocks, the quantized and coded DCT coefficients are adopted as the recovery information. After encrypted by binary pseudo-random sequence, the recovery watermark of each block is embedded into its mapping block. In the detection side, the three-level detection mechanism is applied to detect and locate the tampered regions. The experimental results prove that the proposed method achieves good tamper detection results, and the recovered image has better image quality than other self-recovery fragile watermarking methods.
Highlights
With the widespread use of mobile imaging devices like smart phones, people can obtain and transmit the digital images at any time
The host image is firstly divided into 2 × 2 blocks, and the discrete cosine transform (DCT) transform is applied to each block
From the final column of the table, we can see that the peak signal-to-noise ratio (PSNR) values of the ten watermarked images are all larger than 38 dB, which proves that the proposed variable capacity fragile watermarking achieves good watermark imperceptibility
Summary
With the widespread use of mobile imaging devices like smart phones, people can obtain and transmit the digital images at any time. To improve the tamper detection precision and the quality of restored images, a new self-recovery fragile image watermarking with variable watermark capacity is presented in this paper. In this method, the host image is firstly split into 2 × 2 blocks. Compared with other recoverable fragile watermarking schemes, the strengths of the proposed method are as follows: (i) Based on the analysis of SVD characteristics, a block classification method is designed, which is used to divide the image blocks into smooth blocks and texture blocks; (ii) a variable recovery watermark generation strategy is developed to produce different recovery watermarking bits for different blocks; (iii) a three-level detection strategy is applied to improve the tamper localization accuracy.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
