Geometrically invariant watermarking: synchronization through circular Hough transform

Abstract

This paper addresses a geometrically invariant watermarking method for digital images. Most previous watermarking algorithms perform weakly against geometric distortions, which desynchronize the location for the inserted watermark. Watermark synchronization, which is a process for finding the location for watermark insertion and detection, is crucial for robust watermarking. In this paper, we propose a watermarking method that is robust to geometric distortions. In order to synchronize the location for watermark insertion and detection, we use circular Hough transform, which extracts circular features that are invariant to geometric distortions. The circular features are then watermarked using additive way on the spatial domain. Our method belongs to the category of blind watermarking techniques, because we do not need the original image during detection. Experimental results support the contention that our method is useful and considerably robust against both geometric distortion attacks and signal processing attacks as listed in Stirmark 3.1.

Geometrically invariant color image watermarking scheme using feature points

“…Finally, the experimental results are compared with another feature-based watermarking scheme in ref. [15]. Tables 2 and 3 summarize the detection results in comparison with that of ref.…”

“…Tables 2 and 3 summarize the detection results in comparison with that of ref. [15] against common signal processing and geometric attacks respectively. The tables show the ratios of the number of correctly detected watermarked LIR to the number of original embedded watermarked LIR.…”

“…[15] because of the use of the image normalization. Figure 6(c) shows the simulation result for 2 • rotation.…”

“…Seo et al [14] introduced a content-based image watermarking algorithm based on scale-space representation. Lee et al [15] proposed a new geometrically invariant watermarking method that uses circular Hough transform for watermark synchronization. Through circular Hough transform, the circular features invariant to geometric distortions are extracted.…”

Robust Image Watermarking Algorithm Based on Radon and Analytic Fourier-Mellin Transforms

“…Some proposed several methods using geometrically invariant image features. Lecture [7] used circular Hough transform to achieve the watermark synchronization. The circular Hough transform was adopted to construct the invariant features to geometrical attacks.…”