• Journal of Broadcast Engineering
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• v.22 no.4
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• pp.496-508
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• 2017

In this paper, we propose a Tone Mapping Operator (TMO) that preserves global contrast and precisely preserves boundary information. In order to reconstruct a High Dynamic Range (HDR) image to a Low Dynamic Range (LDR) display by using Threshold value vs. Intensity value (TVI) based on Human Visual System (HVS) and contrast value. As a result, the global contrast of the image can be preserved. In addition, by combining the boundary information detected using Guided Image Filtering (GIF) and the detected boundary information using the spatial masking of the Just Noticeable Difference (JND) model, And improved the perceived image quality of the output image. The conventional TMOs are classified into Global Tone Mapping (GTM) and Local Tone Mapping (LTM). GTM preserves global contrast, has the advantages of simple implementation and fast execution time, but it has a disadvantage in that the boundary information of the image is lost and the regional contrast is not preserved. On the other hand, the LTM preserves the local contrast and boundary information of the image well, but some areas are expressed unnatural like the occurrence of the halo artifact phenomenon in the boundary region, and the calculation complexity is higher than that of GTM. In this paper, we propose TMO which preserves global contrast and combines the merits of GTM and LTM to preserve boundary information of images. Experimental results show that the proposed tone mapping technique has superior performance in terms of cognitive quality.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.4
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• pp.110-122
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• 2014

As multimedia technologies develop, three-dimensional (3D) technologies are attracting increasing attention from researchers. In particular, video quality assessment (VQA) has become a critical issue in stereoscopic image/video processing applications. Furthermore, a human visual system (HVS) could play an important role in the measurement of stereoscopic video quality, yet existing VQA methods have done little to develop a HVS for stereoscopic video. We seek to amend this by proposing a 3D visual attention (3DVA) model which simulates the HVS for stereoscopic video by combining multiple perceptual stimuli such as depth, motion, color, intensity, and orientation contrast. We utilize this 3DVA model for pooling on significant regions of very poor video quality, and we propose no-reference (NR) stereoscopic VQA (SVQA) method. We validated the proposed SVQA method using subjective test scores from our results and those reported by others. Our approach yields high correlation with the measured mean opinion score (MOS) as well as consistent performance in asymmetric coding conditions. Additionally, the 3DVA model is used to extract information for the region-of-interest (ROI). Subjective evaluations of the extracted ROI indicate that the 3DVA-based ROI extraction outperforms the other compared extraction methods using spatial or/and temporal terms.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.42 no.6
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• pp.83-92
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• 2005

This paper presents a watermarking approach that the 1-level Discrete Wavelet Transform(DWT) coefficients of a $64{\ast}64$ binary logo image as watermarks are inserted in LL band and other specific frequency bands of the host image using Multi-Resolution Analysis(MRA) Wavelet transform for copyright protection of image data. The DWT coefficients of the binary logo image are inserted in blocks of LL band and specific bands of the host image that the 3-level DWT has been performed in the same orientation. We investigate Significant Coefficients(SCs) in each block of the frequency areas in order to prevent the quality deterioration of the host image and the watermark is inserted by SCs. When the host image is distorted by difference of the distortion degree in each frequency, we set the thresholds of SCs on each frequency and completely insert the watermark in each frequency of the host image. In order to be invisibility of the watermark, the Human Visual System(HVS) is applied to the watermark. We prove the proper embedding method by experiment. Thereby, we rapidly detect the watermark using this watermarking method and because the small size watermarks are inserted by HVS and SCs, the results confirm the superiority of the proposed method on invisibility and robustness.

• The KIPS Transactions:PartB
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• v.12B no.7 s.103
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• pp.729-736
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• 2005

In this paper. the proposed method for the digital watermarking is based on the multiresolution wavelet transform. The 1-level Discrete Wavelet Transform(DWT) coefficients of a $2N_{wx}{\times}2N_{wy}$ binary logo image used as a watermarks. The LL band and middle frequency band of the host image that the 3-level DWT has been performed are divided into $N_{wx}{\times}N_{wy}$ size and we use large coefficients at the divided blocks to make threshold. we set the thresholds that completely insert the watermark in each frequency of the host image. The thresholds in each frequency of the host image differ each other. The watermarks where is the same positions are added to the larger coefficients than threshold in the blocks at LL band and middle frequency band in order to prevent the quality deterioration of the host image. The watermarks are inserted in LL band and middle frequency band of the host image. In order to be invisibility of the watermark, the Human Visual System(HVS) is applied to the watermark. We prove the proper embedding method by experiment. We rapidly detect the watermark using this watermarking method. And because the small size watermarks are inserted by HVS, the results confirm the superiority of the proposed method on invisibility and robustness.

• Proceedings of the IEEK Conference
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• 2001.06d
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• pp.187-190
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• 2001

In this paper, we present a novel digital watermarking technique based on the concept of multiresolution decomposition and Human Visual System(HVS). Proposed watermarking is to embed watermark by quantization, that is to construct ‘perceptually lossless’quantization matrix, by using a quantization factor for each level and orientation and variance within a band. We compare our approach with another wavelet domain watermarking methods. Simulation results show the superior performance of robustness for variety image distortions.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.11
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• pp.93-101
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• 1992

HVS based transform coding techniques for still images take the lowest spatial frequency and luminance contrast sensitivity as the most crucial factors in determining the image quality perceived by human eye. Only the frequency weighting has been main issue. The proposed Weighted Discrete Cosine Transform (WDCT) has the lowest frequency of about 4 [cyc/deg] in 8$\times$8 subblock with the contrast-weighted DC coefficient. The error criteria have been rederived to adapt the contrast weighting for performance evaluation. The proposed scheme has produced higher quality images compared to the unweighted and other schemes.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.751-754
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• 2001

일반적으로 디지털 컬러 영상의 워터마킹 구현방법은 기존의 워터마킹 방법을 RGB 컬러 성분에 대해 각각 적용하였기 때문에 컬러 영상의 특성을 충분히 고려하지 못했다. 그러나 인간의 시각 체계(HVS : Human Visual System)의 특성을 이용하면 컬러 영상에 더욱 효과적으로 워터마크를 삽입할 수 있다. 본 논문에서는 다해상도 이산 웨이브렛 변환 영역에서의 인간의 시각 체계의 특성을 이용한 컬러 영상 워터마킹 방법을 제안하였다.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.235-238
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• 2001

본 논문에서는 인간시각시스템(HVS)과 블록 DCT를 이용한 효과적인 워터마킹 방법을 제안한다. 워터마크는 시각적으로 인식 가능한 패턴과 비밀키에 의해 생성되고, 인간시각특성에 따라 영상의 중간 주파수 대역을 선택적으로 변조함으로서 삽입된다. 워터마크의 추출에는 원 영상이 필요하며, 추출된 워터마크와 원래의 워터마크와의 상관관계를 통하여 유사성을 판별한다. 제안한 방법의 실험결과, 영상에 삽입된 워터마크는 노이즈, 필터링, JPEG 손실압축등에 강인함을 보여준다.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.104-107
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• 2003

본 논문에서는 웨이브릿 영역에서 HVS 및 NVF 함수를 사용하여 영상특성에 기반한 통계적 판정법을 이용한 적응 워터마크 검출 알고리즘을 판정법을 제안한다. 워터마크는 4레벨로 분해된 웨이브릿 영역에서 JND(just noticeable difference) 특성과 NVF(noise visibility function)를 이용한 통계적 특성을 기반으로 정상상태 가우시안 모델에 따라 지각적 동조 특성을 이용하여 적응적으로 삽입하고, Bayes 이론 및 Neyman-Pearson 정리를 이용한 통계적 판정법을 이용하여 워터마크를 추출함으로써 기존의 통계적 판정법 보다 정확하게 워터마크 존재 유무를 판정 할 수 있음을 확인하였다.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.913-914
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• 2008

This paper presents a method of adaptive image enhancement with dynamic range compression and contrast enhancement. The dynamic range compression is to adaptively enhance the dark area using illumination component of DCT compression block. The contrast enhancement is to modify the image contrast using retinex theory that uses the HVS properties. The block artifacts and other noises, caused by processing in the compression domain, were removed by after processing.