| Summary: | A copyright protection scheme based on visual cryptography for digital
color images is proposed in this work. It is necessary to protect the copyright so
that the image is not misused by others. A binary image is used to mark the
ownership of the digital image. Unlike most conventional watermarking schemes,
the image to be protected is not directly modified by embedding the watermark
into it. Visual cryptography technique is used to generate two share images,
namely ownership share image and master share image.
Firstly, color image is decomposed by it's component color R, G, and B.
Then the image features are extracted using Fourier transform, singular value
decomposition, and voting. The features of the image are used to generate the
master share image, while the ownership share image is formed by using
watermark image and image features. To identify the ownership of the image, the
watermark can be obtained by stacking the master share image with the ownership
share image.
Some experiments are carried out to assess the robustness and security
performance of the proposed scheme. The results show that the proposed scheme
meets the security criteria and robusts against image processing attacks, especially
JPEG compression attack.
Keywords : copyright protection, watermarking, visual cryptography, color
images
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