• Proceedings of the IEEK Conference
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• 2001.06d
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• pp.73-76
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• 2001

In this paper, we utilize a HVS(Human Visual System) watermarking method where watermarks are embedded in a DFT domain. The HVS watermarking method is robust for attacks like JPEC, filtering, noise, etc. But, when images are attacked by basic geometric attacks as cropping, scaling, rotation, a watermarks may not be detected. In this paper, we introduce the HVS watermarking method that inserts references In a domain of LSB(Least Significant Bit) of image. Experimental results show that the proposed method based on HVS watermarking method gives more robustness to the basic geometric attacks compared with original HVS watermarking methods.

• Journal of Korea Multimedia Society
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• v.6 no.5
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• pp.861-869
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• 2003

The rapid growth of multimedia network systems has caused overflowing illegal copies of digital contents. Among digital contents, watermarking technique can be used to protect ownership about the image. Copyright protection involves the authentication of image ownership and the identification of illegal copies of image. In this paper, a new digital watermarking technique using HVS and adaptive scale factor based on the wavelet transform is proposed to use the binary image watermark. The original image is decomposed by 3-level wavelet transform. It is embedded to baseband and high frequency band. The embedding in the baseband is considered robustness, the embedding in the high frequency band is concerned about HVS and invisibility. The watermarking of a visually recognizable binary image used the HVS and random permutation to protect the copyright. From the experimental results, we confirm that the proposed technique is strong to various attacks such as joint photographic experts ground(JPEG) compression, cropping, collusion, and inversion of lines.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1298-1305
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• 2016

This paper presents the development of a short-circuit protection mechanism on a high voltage switch (HVS) board which is built by a series connection of semiconductor switches. The HVS board is able to quickly detect and limit the peak fault current before the signal board triggers off a gate signal. Voltage clamping techniques are used to safely turn off the short-circuit current and to prevent overvoltage of the series-connected switches. The selection method of the main devices and the development of the HVS board are described in detail. Experimental results have demonstrated that the HVS board is capable of withstanding a short-circuit current at a rated voltage of 10kV without a di/dt slowing down inductor. The corresponding short-circuit current is restricted to 125 A within 100 ns and can safely turn off within 120 ns.

• Journal of Digital Contents Society
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• v.6 no.2
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• pp.119-123
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• 2005

We proposed a method of effective watermarking based m HVS. To speak generally, HVS parameters are contrast sensitivity, texture degree, entropy sensitivity and standard of deviation, etc. The aim of this paper is evaluated by the experiments of imperceptibility and correctness of watermark. According to some experimental results, contrast sensitivity function is superior in smooth image. On the other hand, standard of deviation provides good results in rough images. Consequently, how to select the parameters considering image attribute is key problem in effective watermarking.

• The Journal of Korean Association of Computer Education
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• v.9 no.5
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• pp.77-84
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• 2006

In this paper, we propose an adaptive image watermarking algorithm in DWT domain by using HVS(human Visual system) and SOM(Self-Organizing Map) among neural networks. HVS can be described in terms of two properties of HVS: brightness and texture sensitivity. The SOM is used to obtain the local characteristics of image, Therefore, the suitable strength and length of embedded watermark is determined by using HVS and SOM. The experimental results show that proposed method provides a suitable strength and length of watermark and has good perceptual invisibility and robustness for various attacks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.5
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• pp.685-694
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• 1993

A progressive image transmission (PIT) scheme based on the classified transform vector quantization (CVQ) technique using the lapped orthogonal transform (LOT) and human visual system (HVS) weighting is proposed in this paper. Conventional block transform coding of images using DCT produces in general undesirable block-artifacts at low bit rates. In this paper, image blocks are transformed using the LOT and classified into four classes based on their structural properties and further divided adaptively into subvectors depending on the LOT coefficient statistics with HVS weighting to improve the reconstructed image quality by adaptive bit allocation. The subvectors are vector quantized and transmitted progressively. Coding tests using computer simulations show that the LOT/CVQ based PIT of images is a effective coding scheme. The results are also compared with those obtained using PIT/DCTVQ. The LOT/CVQ based PIT reduces the block-artifacts significantly.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.4
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• pp.98-105
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• 1989

Various models incorporating Human Visual System (HVS) with the Hadamard transform (HT) represented by Walsh functions are considered. Using the exact frequency components of HT basis functions, the optimum modulation transfer function (MTF) which has a higher peak frequency than DCT schemes is obtimum modulation transfer function (MTF) which has a higher peak frequency than DCT schemes is obtained analytically and visually. The main criterion, for error measurement, is errors at the block boundaries which is an important factor in transform coding. The scheme which has no inverse HVS is proposed. It causes some degradation of image data but it is insignigicant. Crossing area of 4 blocks is equalized by the HVS weighting coefficients. The HVS weighted coding results in perceptually higher quality images compared with the unweighted scheme.

• The Journal of the Korea Contents Association
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• v.3 no.2
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• pp.31-38
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• 2003

This paper proposes method to insert soong Watermark considering dull HVS properties to big change of Edge and Texture area. While conversion of existent Fourier form can acquire information for whole frequency ingredient of image, but Wavelet transform can look for Edge and Texture area locally. Therefore, use Wavelet transform to use HVS properites, and compare with Xia's Watermarking techniques to use Wavelet transform simply arid experimented these proposal algorithm. Experimented about fidelity and robusthness by attack method that is used in existing paper, and as a result, confirmed that proposal algorithm that use HVS properties is more superior than Xia's techniques.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.2
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• pp.837-856
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• 2016

Underwater image enhancement has received considerable attention in last decades, due to the nature of poor visibility and low contrast of underwater images. In this paper, we propose a new automatic underwater image enhancement algorithm, which combines nonsubsampled contourlet transform (NSCT) domain enhancement techniques with the mechanism of the human visual system (HVS). We apply the multiscale retinex algorithm based on the HVS into NSCT domain in order to eliminate the non-uniform illumination, and adopt the threshold denoising technique to suppress underwater noise. Our proposed algorithm incorporates the luminance masking and contrast masking characteristics of the HVS into NSCT domain to yield the new HVS-based NSCT. Moreover, we define two nonlinear mapping functions. The first one is used to manipulate the HVS-based NSCT contrast coefficients to enhance the edges. The second one is a gain function which modifies the lowpass subband coefficients to adjust the global dynamic range. As a result, our algorithm can achieve contrast enhancement, image denoising and edge sharpening automatically and simultaneously. Experimental results illustrate that our proposed algorithm has better enhancement performance than state-of-the-art algorithms both in subjective evaluation and quantitative assessment. In addition, our algorithm can automatically achieve underwater image enhancement without any parameter tuning.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11C
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• pp.1169-1176
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• 2003

In this paper, we propose a blind watermarking that embeds watermarks into wavelet middle frequency subbands using human visual system. Wavelet middle frequency pairs(MFP) show similar distortion against general image processing attacks such as compression and filtering. So the quantization between MFPs is more robust than conventional methods that directly quantize DWT coefficients. We use a noise visibility function(NVF) to obtain a good visual quality This is able to preserve embedding positions after many attacks. Our experimental results show that the proposed scheme is robust to various image processing such as JPEG, while preserving good visual quality above 44㏈.