17-07-2014, 09:49 AM
A Robust Digital Image-in-Image Watermarking AlgorithmUsing the Fast Hadamard Transform
A Robust Digital Image-in-Image.pptx (Size: 778.24 KB / Downloads: 10)
Objective:
A robust image-in-image watermarking algorithm based on the fast Hadamard transform (FHT) is proposed for the copyright protection of digital images and it use “blind” watermarking process.
To increase the invisibility, a visual model based on original image characteristics is proposed and to increase the reliability of the watermarking, a post-processing technique is proposed.
Existing method:
Most research makes use of a normally distributed random vector as a watermark and where the watermark can only be detected by cross-correlating the received coefficients with the watermark generated by secret key and then comparing an experimental threshold value.
Advantages of new technique:
The FHT image-in-image method involves a “blind” watermarking process that retrieves the watermark without the need for an original image present.
Techniques in watermarking:
One is the spatial domain approach, they embed a watermark into the least significant bits (LSBs) of the image pixels.
The other is the frequency domain approach, used the spread spectrum communication for digital multimedia watermarking and they embed a Gaussian distributed sequence into the perceptually most significant frequency components of container image.
Post processing:
To increase the robustness.
To overcome some geometrical distortions such as rotation, translation and resizing.
Includes incorporation of posteriori estimation of the geometrical transformation and the application of the reverse transform before recovering the watermark.
CONCLUSION
A hybrid watermarking technique for embedding characters or grayscale image watermark into a container digital image based on the FHT for copyright protection is presented.
Proposed method is robust against most of the Stirmark attacks and Checkmark non-geometric attacks.
This offers a significant advantage in shorter processing time and ease of hardware implementation