• The Journal of the Korea Contents Association
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• v.11 no.1
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• pp.9-15
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• 2011

Zero-watermarking is a digital watermarking technique that can escape from data distortion and quality degradation by no watermark insertion into digital images to be watermarked. This paper proposes DCT0CRT, a CRT-based zero-watermarking technique in the domain of DCT. One of the DC and low-frequency AC coefficients of each DCT block chosen in chaotic way from an image is selected by testing whether it satisfies the CRT-based condition matching with the watermark bit to be embedded. Such selection information forms a key to extract the watermark from the watermarked image. Experimental results show that the image quality watermarked by DCT0CRT is better than that watermarked by any other CRT-based watermarking techniques and the inserted watermark is robust against some common attacks such as sharpening, blurring, and JPEG lossy compression.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.3
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• pp.57-65
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• 2010

This research aimed to prevent illegal distribution and reproduction of digital cadastral map information using digital watermarking. To this end, a digital watermarking was developed in consideration of the properties of cadastral maps and based on watermarking methods, after which its performance was evaluated. A watermark key and a one-way function was used to compensate for the algorithm and, therefore, watermarking security, based on the existing research results. In these ways, the present method meets the requirements for fidelity, robustness, false positive rate and the maintenance of consistent topology. The advanced techniques suggested in this paper were devised so as to be suitable for vector data such as GIS and navigation data as well as cadastral maps. Moreover, if the existing methodology is further improved, it could be expected to be used even more widely.