• Journal of the Institute of Convergence Signal Processing
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• v.13 no.4
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• pp.187-193
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• 2012

An image authentication scheme for gray scale image through embedding a digital watermark by quantization of Integer Wavelet Transform (IWT) coefficients of the image is proposed in this paper. Proposed method is designed to detect modification of an image and to identify tampered location of the image. To embed the watermark mid-frequency band of a second level IWT was used. An approximation of the original image based on LL band was stored in LSB bits of the pixel data as a recovery mark for restoration of the image. Watermarked image has achieved a good PSNR of 40 dB compared to original cover image. Restored image quality was also very good with a PSNR of more than 35 dB compared to unmodified watermarked image even when 25% of the received image is cropped. Thus, the proposed method ensures a proper balance between the fidelity of the watermarked image and the quality of the restored image.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.2
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• pp.17-22
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• 2014

Watermarking is one of the methods that insist on a copyright as it append digital signals in digital informations like still mobile image, video, other informations. This paper proposed an improved DCT-based watermarking scheme using quantized coefficients of image. This process makes quantized coefficients through a Discrete Cosine Transform and Quantization. The watermark is embedded into the quantization coefficients in accordance with location(key). The quantized watermarked coefficients are converted to watermarked image through the inverse quantization and inverse DCT. Watermark extract process only use watermarked image and location(key). In watermark extract process, quantized coefficients is obtained from watermarked image through a DCT and quantization process. The quantized coefficients select coefficients using location(key). We perform it using inverse DCT and get the watermark'. Simulation results are satisfied with high quality of image (PSNR) and Normalized Correlation(NC) from the watermarked image and the extracted watermark.

• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.377-382
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• 2003

We propose a new optical watermarking method, which can protect the copyright of digital data, using a binary phase hologram and a Mach-Zehnder interferometer. Using a simulated annealing algorithm, the binary phase hologram of the mark image to be hidden is designed. We obtained a watermarked image by linearly superposing the hologram, which is the watermark, in the original image. The extraction processing of the mark image from the watermarked image is achieved by placing the phase-modulated watermarked image on a LCD in one path and the phase-modulated original image on another LCD in the other path in the Mach-Zehnder interferometer. The mark image was obtained by inverse Fourier transforming the phase modulated interference intensity. We confirmed that the proposed method is robust for the cropped images through computer simulation, and we implemented it optically using LCDs which are phase modulation devices.

• 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 Broadcast Engineering
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• v.9 no.1
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• pp.64-73
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• 2004

A robust watermarking algorithm is proposed for 3D mesh models. Watermark is inserted into the 2D image which is extracted from the target 3D model. Each Pixel value of the extracted 2D image represents a distance from the predefined reference points to the face of the given 3D model. This extracted image is defined as “range image” in this paper. Watermark is embedded into the range image. Then, watermarked 3D mesh is obtained by modifying vertices using the watermarked range Image. In extraction procedure, the original model is needed. After registration between the original and the watermarked models, two range images are extracted from each 3D model. From these images. embedded watermark is extracted. Experimental results show that the proposed algorithm is robust against the attacks such as rotation, translation, uniform scaling, mesh simplification, AWGN and quantization of vertex coordinates.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.407-408
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• 2006

In this paper, we propose a new reversible image authentication technique based on watermarking where if the image is authentic, the distortion due to embedding can be completely removed from the watermarked image after the hidden data has been extracted. This technique utilizes histogram characteristics of the difference image and modifies pixel values slightly to embed more data than other reversible data hiding algorithm. The proposed scheme is quite simple and the execution time is rather short. Experimental results demonstrate that the proposed scheme can detect any modifications of the watermarked image.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.10
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• pp.3591-3606
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• 2014

In this paper, a robust watermarking scheme is proposed that uses the scale-invariant feature transform (SIFT) algorithm in the discrete wavelet transform (DWT) domain. First, the SIFT feature areas are extracted from the original image. Then, one level DWT is applied on the selected SIFT feature areas. The watermark is embedded by modifying the fractional portion of the horizontal or vertical, high-frequency DWT coefficients. In the watermark extracting phase, the embedded watermark can be directly extracted from the watermarked image without requiring the original cover image. The experimental results showed that the proposed scheme obtains the robustness to both signal processing and geometric attacks. Also, the proposed scheme is superior to some previous schemes in terms of watermark robustness and the visual quality of the watermarked image.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.12
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• pp.5268-5285
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• 2016

Digital watermarking techniques are widely applied to protect the integrity and copyright of digital content. In a majority of the literature for watermarking techniques, the watermarked image often causes some distortions after embedding a watermark. For image-quality-concerned users, the distortions from a watermarked image are unacceptable. In this article, we propose a removable watermarking scheme that can restore an original-like image and resist signal-processing attacks to protect the ownership of an image by utilizing the property of singular value decomposition (SVD). The experimental results reveal that the proposed scheme meets the requirements of watermarking robustness, and also reestablishes an image like the original with average PSNR values of 59.07 dB for reconstructed images.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.109-112
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• 2002

In this paper, we propose the efficient digital watermarking scheme to transmit effectively the compressed medical image that embedded with watermarking data in mobile Internet access channel. The wireless channel error based on multiple access interference (MAI) is closely related to the length of spreading sequence in CDMA system. Also, the fixed length coded medical image with watermark bit stream can be classified by significance of source image. In the simulation, we compare the peak signal to noise ratio (PSNR) performance when the watermarked image with a simple symbol and when the watermarked image with a text file is transmitted using variable length of spreading sequences in case of limited length of spread sequence.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.18-21
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• 2007

Digital image watermarking is a technology used in copyrighting of digital images by embedding unremovable informations. In this paper, a pixel-domain look-up-table-based watermarking algorithm is presented. With this methodology, the watermark was embedded in the host image, but we did not observe any distortion at certain specific region of interest. This means the proposed method is preferred in case of satellite images. Then, the image manipulation tool which is called 'StirMark' will be used to perform many kinds of attacks such as rotation, scaling, filtering and compression on the watermarked image. Finally, the effectiveness of a watermarking technique in terms of 'robustness' and 'data integrity' criteria will be measured by calculating PSNR of watermark and watermarked image.