Browsing by Author "Ozbek, Nukhet"

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Citation - Scopus: 5
Interactive quality assessment for asymmetric coding of 3D video
(IEEE, 2011) Nükhet Özbek; Gizem Ertan; Oktay Karakuş; Ertan, Gizem; Karakus, Oktay; Ozbek, Nukhet
In stereoscopic 3D video it is known that humans can perceive high quality 3D video provided that one of the views in high quality. Hence in stereo video encoding the best overall rate vs. perceived-distortion performance may be achieved by asymmetric coding which is reduction of the spatial or quantization resolution of the auxiliary view while keeping the reference view in full resolution. In this paper we propose an interactive quality assessment method to evaluate perceptual quality for asymmetric coding of 3D video. Subjective Evaluation of Stereo VIdeo Quality (SESVIQ) is proposed as stereo extension of SAMVIQ (Subjective Assessment Methodology for VIdeo Quality) methodology of EBU. We conducted subjective experiments to compare different algorithms such as symmetric over asymmetric rate allocation or spatial over SNR (signal-to-noise ratio) scaling of the auxiliary view. Test results show that the interactive test methodology gives more reliable results than conventional sequential test methodology especially for low bitrate scenarios. © 2011 IEEE. © 2011 Elsevier B.V. All rights reserved.
Citation - Scopus: 2
On Optimal Weights in a PSNR-Based Objective Stereo Video Quality Measure
(IEEE, 2009) Nukhet Ozbek; Ozbek, Nukhet
In stereoscopic 3D video it is well-known that humans can perceive high quality 3D video provided that one of the views is in high quality. Hence in stereo video encoding the best overall rate vs. perceived-distortion performance may be achieved by reduction of the spatial temporal and/or quantization resolution of the second view while keeping the first view in full resolution. Objective stereo video quality metric is a crucial point for the success of unequal rate allocation. Since the perceived 3D video quality does not correlate well with the average PSNR of the two views we proposed a new quantitative measure using a weighted combination of two PSNR values and a jerkiness measure [1]. In this paper we investigate whether the PSNR weights should be related with spatial activity in different scaling options and video contents. Spatial activity is examined in terms Of blockiness and blur. The optimal weights for some specific experiments are determined by matching i.e. searching the best correlation between subjective quality test results and the objective measure scores on a set of test videos.
Citation - WoS: 2
Citation - Scopus: 3
QUALITY LAYERS IN SCALABLE MULTI-VIEW VIDEO CODING
(IEEE, 2009) Nukhet Ozbek; A. Murat Tekalp; Tekalp, A. Murat; Ozbek, Nukhet
The Quality Layers concept is proposed and adopted in the JSVM in order to ensure an optimal adaptation in a rate-distortion sense [1]. In this paper it is extended to multi-view case for scalable coding of multi-view videos (MVV). Rate-visual-distortion optimized rate allocation among the views is necessary for efficient transport of multi-view data over the Internet. This paper addresses a standard compatible approach to solve the problem. Experimental results are presented that demonstrate the effectiveness of the proposed method for several multi-view videos.
Citation - WoS: 1
Citation - Scopus: 2
Rate-visual-distortion optimized extraction with quality layers for scalable coding of stereo videos
(IEEE, 2008) Nükhet Özbek; Murat A. Tekalp; Tekalp, A. Murat; Ozbek, Nukhet
The Quality Layers concept is proposed and adopted in the JSVM in order to ensure an optimal adaptation in a ratedistortion sense [1]. In this paper it is extended to multiview case for scalable coding of stereo videos. Rate-visualdistortion optimized rate allocation among the views is necessary for efficient transport of 3DTV data over the Internet. This paper addresses a standard compatible approach to solve the problem. Experimental results are presented that demonstrate the effectiveness of the proposed method for several stereo videos. © 2008 IEEE. © 2009 Elsevier B.V. All rights reserved.