Browsing by Author "Day, ML"

Now showing 1 - 2 of 2

Rotation, scaling, and translation resilient image watermarking with side information at encoder
(2002)
Day, ML
;
Jou, IC
;
Lee, SY
;
資訊工程學系
;
Department of Computer Science
We propose a rotation, scaling and translation (RST) resilient blind image watermarking technique by using Fourier-Mellin transform and informed coding, where watermark detection does not require the existence of the original image. Although the Fourier-Mellin invariant domain is recognized to be nearly RST invariant, which supposedly would make it an ideal space for watermark embedding, however the inverse Log-Polar map (ILPM) could severely destroy the embedded watermark. Therefore a very strong watermark has to be employed to survive the self-destruction process from ILPM, but in turn this leads to a poorly watermarked image. To overcome this problem we introduce the concept of informed coding by embedding a slightly weaker watermark into the image so that both transparency and robustness can be achieved. Experimental results demonstrate that the resulting watermark is robust to a variety of image processing attacks.
Watermark re-synchronization using sinusoidal signals in DT-CWT domain
(2004)
Day, ML
;
Lee, SY
;
Jou, IC
;
資訊工程學系
;
Department of Computer Science
Embedding sinusoidal signals or tiles patterns into image in the spatial domain to form some peaks is an effective technique for geometric invariant image watermark detection. However, there are two drawbacks in these spatial domain based schemes: one is poor picture quality of resulting watermarked image and the other is weak peaks visibility which is hard to detect. The previous works suffer from requiring a very strong watermark embedding to ease re-synchronization peaks finding, which in turn leads to a poorly watermarked image. To overcome this problem, we explore embedding sinusoidal signals individually in each of the selected sub-bands of dual-tree complex wavelet transform domain (DT-CWT), and then detecting the re-synchronization peaks by using the accumulated embedding sub-bands. Experimental results demonstrate that by adopting our approach, the resulting re-synchronization peaks are robust to rotation, scaling and translation attacks while preserving the visual quality of the watermarked image, thereby resolve the unavoidable dilemma faced by the other schemes.