Lark Kwon Choi

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We introduce a new video quality database that models video distortions in heavily-trafficked wireless networks and that contains measurements of human subjective impressions of the quality of videos. The new LIVE Mobile Video Quality Assessment (VQA) database consists of 200 distorted videos created from 10 RAW HD reference videos, obtained using a RED ONE(More)
We propose a referenceless perceptual fog density prediction model based on natural scene statistics (NSS) and fog aware statistical features. The proposed model, called Fog Aware Density Evaluator (FADE), predicts the visibility of a foggy scene from a single image without reference to a corresponding fog-free image, without dependence on salient objects(More)
Newly developed HTTP-based video streaming technology enables flexible rate-adaptation in varying channel conditions. The users' Quality of Experience (QoE) of rate-adaptive HTTP video streams, however, is not well understood. Therefore, designing QoE-optimized rate-adaptive video streaming algorithms remains a challenging task. An important aspect of(More)
Newly developed hypertext transfer protocol (HTTP)-based video streaming technologies enable flexible rate-adaptation under varying channel conditions. Accurately predicting the users' quality of experience (QoE) for rate-adaptive HTTP video streams is thus critical to achieve efficiency. An important aspect of understanding and modeling QoE is predicting(More)
1. Introduction Video traffic is exponentially increasing over wireless networks due to proliferating video technology and the growing desire for anytime, anywhere access to video content. Cisco predicts that two-thirds of the world's mobile data traffic will be video by 2017 [1]. This imposes significant challenges for managing video traffic efficiently to(More)
We announce a new video quality model (VQM) that accounts for the perceptual impact of variable frame delays (VFD) in videos with demonstrated top performance on the laboratory for image and video engineering (LIVE) mobile video quality assessment (VQA) database. This model, called VQM_VFD, uses perceptual features extracted from spatialtemporal blocks(More)
The purpose of this study was to determine the effect of material and design on the force and stress required to permanently deform metal brackets. Fourteen types of metal brackets were categorized according to raw material composition, slot torque degree, and wing type. Five types of raw materials, three types of slot torque degree, and four types of wing(More)
Motion can reduce the visibility of flicker distortions. We performed human subjective tests to investigate how motion influences the visibility of flicker distortions in naturalistic videos. Forty three naïve subjects participated in two tasks (“follow the moving object” and “view freely”) and reported their percepts on 36 test videos. Flicker distortions(More)
Motion can impair the perception of other visual changes. Suchow and Alvarez (2011a, Current Biology, 21, 140-143) recently demonstrated a striking 'motion silencing' illusion, in which the salient changes among a group of objects' luminances (or colors, etc) appear to cease in the presence of large, coherent object motion. To understand why the visual(More)
We study the influence of motion on the visibility of flicker distortions in naturalistic videos. A series of human subjective studies were executed to understand how motion silences the visibility of flicker distortions as a function of object motion, flicker frequency, and video quality. We found that flicker visibility is strongly reduced when the speed(More)