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Predicting Visual Discomfort Using Object Size and Disparity Information in Stereoscopic Images
Hosik Sohn,Yong Ju Jung,Seong-il Lee,Yong Man Ro IEEE 2013 IEEE transactions on broadcasting Vol.59 No.1
<P>This paper proposes object-dependent disparity features to predict the visual discomfort in stereoscopic 3-D images. The proposed object-dependent disparity features quantify the level of visual comfort influenced by disparity gradient of nearby objects and object width, respectively. They consist of relative disparity (mean of disparity difference between nearby objects) and object thickness (ratio of mean width to mean absolute disparity of an object). The prediction performance of the proposed disparity features is evaluated using various types of stereoscopic images. Experimental results demonstrate that the combined use of the proposed object-dependent disparity features substantially improve the prediction performance of the conventional disparity magnitude- and spatial complexity-related features. The performance gain ranges from 0.045 to 0.135 of correlation coefficient, compared with the feature combinations used in the conventional visual comfort metrics.</P>
Privacy Protection in Video Surveillance Systems: Analysis of Subband-Adaptive Scrambling in JPEG XR
Hosik Sohn,De Neve, Wesley,Yong Man Ro IEEE 2011 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDE Vol.21 No.2
<P>This paper discusses a privacy-protected video surveillance system that makes use of JPEG extended range (JPEG XR). JPEG XR offers a low-complexity solution for the scalable coding of high-resolution images. To address privacy concerns, face regions are detected and scrambled in the transform domain, taking into account the quality and spatial scalability features of JPEG XR. Experiments were conducted to investigate the performance of our surveillance system, considering visual distortion, bit stream overhead, and security aspects. Our results demonstrate that subband-adaptive scrambling is able to conceal privacy-sensitive face regions with a feasible level of protection. In addition, our results show that subband-adaptive scrambling of face regions outperforms subband-adaptive scrambling of frames in terms of coding efficiency, except when low video bit rates are in use.</P>
Hosik Sohn,Yong Ju Jung,Seong-Il Lee,Speranza, Filippo,Yong Man Ro IEEE 2014 IEEE transactions on circuits and systems for vide Vol.24 No.5
<P>This paper proposes a new disparity remapping framework to improve the visual comfort of stereoscopic images. The proposed framework adaptively remaps disparities of a scene according to different causes of visual discomfort. A linear disparity remapping is first performed in order to address visual discomfort induced by excessive disparities. This linear remapping changes the disparities of the scene to obtain an overall target disparity range. Then, a nonlinear disparity remapping process selectively adjusts the disparity of problematic local disparity ranges according to their contribution to the visual discomfort. The proposed nonlinear disparity remapping process enables us to minimize the loss in perceived depth range while further improving visual comfort. The effectiveness of the proposed disparity remapping framework has been successfully evaluated by subjective assessments of visual comfort and naturalness. Experimental results demonstrate the validity of the proposed remapping framework. More importantly, we show that the nonlinear refinement of disparity in problematic regions can efficiently improve visual comfort while maintaining the naturalness of the scene.</P>
손호식(Hosik Sohn),전용주(Yong Ju Jung),이성일(Seong-il Lee),노용만(Yong Man Ro),박현욱(Hyun Wook Park) 한국HCI학회 2011 한국HCI학회 학술대회 Vol.2011 No.1
본 논문에서는 대칭 및 비대칭 부호화된 스테레오스코픽 (Stereoscopic) 영상의 품질 평가를 위한 영상 평가 메트릭을 제안한다. 제안하는 방법은 스테레오스코픽 영상의 품질 측정을 위하여 단안 영상의 품질을 측정하는 동시에 좌안과 우안 영상 품질의 비대칭성을 정량화하여 스테레오스코픽 영상의 전체 품질을 측정한다. 주관적 품질 평가 수행을 통하여 제안된 객관적 품질 측정 메트릭을 검증하였으며, 그 결과 기존에 제안된 스테레오스코픽 영상 품질 평가 메트릭과 비교하여 주관적 품질과의 상관관계가 높아진 것을 보였다. In this paper, we propose a stereoscopic image quality metric considering binocular asymmetry. To estimate the overall visual quality of stereoscopic images, the proposed approach measures the quality of individual monoscopic images while quantifies the amount of binocular asymmetry between left eye and right eye images. The validity of our quality metric has been verified using subjective assessment. Experimental results show that the proposed stereoscopic image quality metric is more correlated with subjective image quality in comparison with previous approach.
Yong Jung,Hosik Sohn,Seong-il Lee,Yong Ro IEEE 2014 IEEE transactions on consumer electronics Vol.60 No.1
<P>Visual discomfort is caused by several factors such as accommodation-vergence conflict and window violation in conventional stereoscopic displays. To ensure comfortable conditions in the stereoscopic viewing, it is essential to develop an effective way of improving visual comfort in stereoscopic displays. This paper proposes a new method for visual comfort improvement that adjusts the disparity of a scene under the guidance of an objective assessment metric of visual comfort. The proposed method employs a visual comfort assessment metric that takes into account various discomfort factors in the stereoscopic viewing. The results of subjective assessment experiments demonstrate that the proposed method can efficiently improve visual comfort in the stereoscopic viewing.</P>
Exploiting Independent Decoding of ROIs in H.264/AVC SVC for Low-Resolution Displays
Esla Anzaku Timothy,Hosik Sohn,Yong Man Ro 한국멀티미디어학회 2009 한국멀티미디어학회 학술발표논문집 Vol.2009 No.1
Nowadays, a significant amount of video content is created with a high spatial resolution. However, users with low-resolution displays typically only have the option of viewing a down-sampled version of the original content. In this paper, we discuss independent decoding of Regions of Interest in H.264/AVC Scalable Video Coding. This tool can be employed to improve the viewing experience with low-resolution displays. A possible application is outlined as well, focusing on zooming functionality.
Visual discomfort visualizer using stereo vision and time-of-flight depth cameras
Yong Ju Jung,Hosik Sohn,Yong Man Ro IEEE 2012 IEEE transactions on consumer electronics Vol.58 No.2
<P>Visual discomfort monitoring is an important technique for comfortable viewing of stereoscopic images. This paper proposes a novel monitoring system of visual discomfort that takes advantages of a fusion camera system equipped with stereo vision cameras and a time-of-flight camera. We improve disparity map enhancement technique to obtain a high-quality disparity map that is aligned to the right view color image coordinate. The captured stereo-plusdisparity images are used for visual discomfort visualizer that automatically predicts overall degree of perceived visual discomfort and visualizes which regions are problematic in terms of visual discomfort. The proposed visual discomfort visualizer is based on visual importance of image scenes, resulting in considerable improvement in prediction performance of visual discomfort. The experimental results showed that the proposed system could generate enhanced disparity maps and achieve visual discomfort prediction accuracy that is feasible for practical applications.</P>
Yong Ju Jung,Hosik Sohn,Seong-il Lee,Speranza, Filippo,Yong Man Ro IEEE 2013 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDE Vol.23 No.8
<P>In human vision, the depth of focus (DOF) blur is important to perceive single binocular vision. Unfortunately, conventional stereoscopic displays cannot provide a natural DOF blur effect. Synthetic DOF blur that simulates the natural DOF blur effect could be useful for reducing the visual discomfort in stereoscopic displays. However, the incorrect introduction of artificial blur in the image might also have negative effects. This paper proposes a selective DOF blur technique that is applied only to local regions that induce high visual discomfort but are less visually important. We employ a visual importance analysis to obtain reasonable estimates of the areas/objects that are likely to be attended using saliency maps. After identifying the regions likely to cause discomfort because of excessive relative disparity, we apply low-pass filtering for the less-salient neighboring pixels of the discomfort regions. We demonstrate that the DOF blur simulation for less important background regions that induce visual discomfort is helpful in reducing the visual discomfort in stereoscopic viewing.</P>