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Title: An improved watermarking algorithm using variable block image feature
Authors: Dagher, Issam 
Hanna, Patrick
Affiliations: Department of Computer Engineering 
Keywords: Watermarking
Variable block
Harris detector
PN sequence
GOLD sequence
Decimal Sequence
Issue Date: 2017
Part of: Journal of pattern recognition and images analysis
Volume: 27
Issue: 2
Start page: 289
End page: 300
The ease in digital imaging has led to a decrease in image fidelity where illegal reproduction of multimedia information has become difficult to detect. The most challenging problem is to protect image copyright against illegal copies. Therefore a watermark detection process is required to verify the owner of the image. This paper proposes a blind algorithm to extract the watermark. This algorithm is robust against noise and geometric attacks for grayscale images. Robust feature points are detected using the Harris Detector. In the embedding stage, sequences are placed into regions located around feature points. The sequences used are PN, Gold and decimal. In the extraction process, image features are re-allocated using the same detector. Each feature point is used as a center of an N × N region. This region is moved horizontally and vertically within its neighboring pixels. Each move should be registered in a matrix as a correlation value of this region with the initial sequence. This procedure is repeated for all feature points till we find all the watermarked regions. The maximum correlation obtained will determine the center of the watermarked region. The proposed algorithm is robust against a wide variety of tests and is compared to other schemes.
Ezproxy URL: Link to full text
Type: Journal Article
Appears in Collections:Department of Computer Engineering

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