With the rapid growth of digital multimedia and internet technologies has made copyright protection, copy protection, and integrity verification three important issues in the digital world. The digital watermarking technique is approached to solve this problem. Traditional watermarking algorithms are mostly based on discrete transform domains, such as the discrete cosine transform, discrete Fourier transform (DFT), and discrete wavelet transform (DWT). Most of these algorithms are good for only one purpose. Recently, some multipurpose digital watermarking methods have been presented, which can achieve the goal of content authentication and copyright protection simultaneously. However, they are based on DWT or DFT. Lately, several robust watermarking schemes based on vector quantization (VQ) have been presented, but they can only be used for copyright protection. In this design multipurpose digital image watermarking method based on the multistage vector quantizer structure is developed using Matlab, which can be applied to image authentication and copyright protection.

    The basic idea of multistage VQ is to divide the encoding task into successive stages, where the first stage performs a relatively crude quantization of the input vector using a small codebook. Then, a second-stage quantizer operates on the error vector between the original and quantized first-stage output. The quantized error vector then provides a second approximation to the original input vector thereby leading to a refined or more accurate representation of the input. A third-stage quantizer may then be used to quantize the second-stage error to provide a further refinement and so on. The semi-fragile watermark and the robust watermark are embedded in different VQ stages using different techniques, and both can be extracted without the original image. Different attack methods applied to show the effectiveness of the method. Matlab simulation results shown in the video demonstrate that the method is more effective in terms of robustness and fragility.

Design Process

  • Multistage Vector Quantization
  • Embedding Process
    • Robust Watermark Embedding Process
    • Semi-Fragile Watermark Embedding Process
  • Extraction Process
    • Watermark Extraction from the Original Image
  • Attack Methods
    • Rotation Attacks
    • Crop Attack
    • Blur Method Attack
    • Contrast Attack

Reference Paper: Multipurpose Image Watermarking Algorithm Based on Multistage Vector Quantization

Author’s Name: Zhe-Ming Lu, Dian-Guo Xu, and Sheng-He Sun

Source: IEEE

Year: 2005

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SIMULATION VIDEO DEMO