• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.3
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• pp.615-622
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• 2007

In general, Harris detector is commonly used for finding salient points in watermarking systems using feature points. Harris detector is a kind of combined comer and edge detector which is based on neighboring image data distribution, therefore it has some limitation to find accurate salient points after watermark embedding or any kinds of digital attacks. In this paper, we have used cross reference points which use not data distribution but geometrical structure of a normalized image in order to avoid pointing error caused by the distortion of image data. After normalization, we find cross reference points and take inverse normalization of these points. Next, we construct a group of triangles using tessellation with inversely normalized cross reference points. The watermarks are affine transformed and transformed-watermarks are embedded into not normalized image but original one. Only locations of watermarks are determined on the normalized image. Therefore, we can reduce data loss of watermark which is caused by inverse normalization. As a result, we can detect watermarks with high correlation after several digital attacks.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.508-511
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• 2009

The infringement of the copyright is a problem by the distribution of digital contents copied illegally. The digital watermark is expected as a thing preventing unjust copying by burying information in digital data such as image, animation, the sound, TV, radio and movies. [1] [2]But a noise is included in a digital watermark reproduction image. So there is the case that the certification of the reproduction image has difficulty with. If a computer cannot recognize the information reproduced from digital watermarking, the information does not have a meaning. This paper aimed at improvement of the proof of a digital-watermarking reproduction image. And it is verified whether the difference of the form of a character affects the degree of correlation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.7A
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• pp.1037-1043
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• 2000

In this paper we present an object-based watermarking scheme, which cuts out several featured portions from an image and casts chaotic sequences as a watermark into the extracted object image in the discrete wavelet domain with respect to the models of the human visual system. In such a way we can insert watermark to several objects of an image separately. Advantages of the proposed scheme include that it can protect featured object out of an image selectively as well as entire image and casts watermark sequences according to human visual masking utilizing the time-frequency localization property of the wavelet transform.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.12
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• pp.3100-3116
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• 2012

Reversible data hiding enables the embedding of messages in a host image without any loss of host content, which is proposed for image authentication that if the watermarked image is deemed authentic, we can revert it to the exact copy of the original image before the embedding occurred. In this paper, we present an improved histogram-based reversible data hiding scheme based on prediction and sorting. A rhombus prediction is employed to explore the prediction for histogram-based embedding. Sorting the prediction has a good influence on increasing the embedding capacity. Characteristics of the pixel difference are used to achieve large hiding capacity while keeping low distortion. The proposed scheme exploits a two-stage embedding strategy to solve the problem about communicating peak points. We also present a histogram shifting technique to prevent overflow and underflow. Performance comparisons with other existing reversible data hiding schemes are provided to demonstrate the superiority of the proposed scheme.

• 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.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.9 no.3
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• pp.39-52
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• 1999

In this paper we propose a new watermarking technique for copyright protection of images. The proposed technique is based on a spatial masking method with a spatial scale parameter. In general it becomes more robust against various attacks but with some degradations on the image quality as the amplitude of the watermark increases. On the other hand it becomes perceptually more invisible but more vulnerable to various attacks as the amplitude of the watermark decreases. Thus it is quite complex to decide the compromise between the robustness of watermark and its visibility. We note that watermarking using the spread spectrum is not robust enought. That is there may be some areas in the image that are tolerable to strong watermark signals. However large smooth areas may not be strong enough. Thus in order to enhance the invisibility of watermarked image for those areas the spatial masking characteristics of the HVS(Human Visual System) should be exploited. That is for texture regions the magnitude of the watermark can be large whereas for those smooth regions the magnitude of the watermark can be small. As a result the proposed watermarking algorithm is intend to satisfy both the robustness of watermark and the quality of the image. The experimental results show that the proposed algorithm is robust to image deformations(such as compression adding noise image scaling clipping and collusion attack).

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.6
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• pp.43-50
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• 2007

In this paper we propose a method that identifies users at H.264 streaming using watermarking with fingerprints. The watermark can efficiently reduce the potential danger of forgery or alteration. Especially a biometric watermark has various advantages. Among entire biometric characteristics, the fingerprint is the most convenient and economical. In this paper we propose a novel fingerprint-based watermarking technique that can survive under very low bit-rate compression. The proposed algorithm consists of enhancement of a fingerprint image, the watermark generation using the extracted feature coordinates, watermark insertion using discrete wavelet transform, and authentication. The proposed algorithm can achieve robust watermark extraction against 0.264 compressed videos.

• Journal of Internet Computing and Services
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• v.9 no.1
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• pp.33-41
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• 2008

Due to the advantage of wavelet transform such as the compatibility with JPEG2000, multi-resolution decomposition, and application of HVS(Human Visual System), watermarking algorithm based on wavelet transform (DWT) is recently mast interesting research subject. However, mast of researches are focused on theoretical aspects for the robustness rather than practical usage, and. may be not suitable too much complicated to use in practice. In this paper, robust logo watermarking algorithm based on DWT is proposed for large and huge data processing. The proposed method embeds the logo watermark by mapping of $8{\times}8$ blocks in order of the number of '1' of the original image and the randomized watermark image with LFSR. The original image is transformed by 2 level wavelet. The experimental results shows that the watermark is embedded successfully, and the proposed algorithm has the valuable robustness from the image processing like JPEG compression, low pass filter, high pass filter and changes in brightness and contrast.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.2
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• pp.96-106
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• 2002

In this paper, we propose a new image-watermarking scheme lot arbitrarily shaped object based on Polar coordinates Shape Adaptive Discrete Transform (PSADT). Using log-polar coordinates conversion and shape adaptive discrete transform, the proposed watermarking method can be applied to any arbitrarily shaped image-object such as MPEG-4 VOP and is much more robust to geometrical attacks such as rotation and scaling than the conventional methods.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1073-1080
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• 2011

In this paper, we propose a novel digital watermarking method by virtual optics which secures multimedia information such as images, videos and sounds. To secure the multimedia data, we use Fresnel transform which describes the diffraction phenomena of the waves. Also, this method attaches the random phase function to Fresnel transform so that original image and watermark image would be gaussian random vectors. The complex numbers of watermark by Fresnel transform are separated the real part and the imaginary part. The former is embedded in original image as a encoding key imperceptibly and the latter is used for detecting the watermark as a decoding key. This method for digital watermarking ensures that watermark can be successfully registered and extracted from the watermarked image. Further, it provides the robustness to signal processing operation and geometric distortion and proves the strong resilience against cropping attack. The performance evaluation of the experiment is carried out with PSNR, and the numerical simulation results show the efficiency of the proposed method.