Subjective study on compressed asymmetric stereoscopic video

2014 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2014

The problem of determining the best level of asymmetry has been addressed by several recent works with the aim to guarantee an optimal binocular perception while keeping the minimum required information. To do so, subjective experiments have been conducted for the definition of an appropriate threshold. However, such an approach is lacking in terms of generalization because of the content variability. Moreover, using a fixed threshold does not allow an adaptation to the content and to the images' quality. The traditional asymmetric stereoscopic coding methods apply a uniform asymmetry by considering that all regions of an image have the same perceptual relevance which is not in compliance with the characteristics of human visual system (HVS). Consequently, this paper describes a fully automated model that dynamically determines the best bounds of asymmetry for each region of the image. Based on the Binocular Just Noticeable Difference (BJND) and the depth level in the scene, the proposed method achieves non-uniform reduction of spatial resolution of one view of the stereo pair with the aim to reduce bandwidth requirement. Experimental results show that the proposed method results in up to 43% of bitrate saving while outperforming the widely used asymmetric coding approaches in terms of 3D visual quality.

IEEE Transactions on Image Processing, 2013

The quality assessment of impaired stereoscopic video is a key element in designing and deploying advanced immersive media distribution platforms. However, a widely accepted quality metric to measure impairments of stereoscopic video is still to be developed. As a step towards finding a solution to this problem this paper proposes a full reference stereoscopic video quality metric to measure the perceptual quality of compressed stereoscopic video. A comprehensive set of subjective experiments are performed with 14 different stereoscopic video sequences, which are encoded using both the H.264 and High Efficiency Video Coding (HEVC) compliant video codecs, to develop a subjective test results database of 116 test stimuli. The subjective results are analyzed using statistical techniques to uncover different patterns of subjective scoring for symmetrically and asymmetrically encoded stereoscopic video. The subjective results database is subsequently used for training and validating a simple but effective stereoscopic video quality metric considering heuristics of binocular vision. The proposed metric performs significantly better than state-of-the-art stereoscopic image and video quality metrics in predicting the subjective scores. The proposed metric and the subjective results database will be made publicly available and it is expected that the proposed metric and the subjective assessments will have important use cases in advanced 3-Dimensional (3D) media delivery systems.

2009 3DTV Conference: The True Vision - Capture, Transmission and Display of 3D Video, 2009

This paper presents results for full and mixed resolution stereo video coding including subjective and objective evaluation for 3DTV on Mobile devices. For this, objective as well as subjective tests have been carried out with different sequences at different image sizes and evaluated on two different stereoscopic displays. The subjective tests showed, that for uncoded sequences full resolution was rated better, however for coded sequences at low bit rates mixed resolution was rated better. An unsharp masking algorithm for up-sampling the lower resolution view only partially improved the overall quality because coding artifacts were strengthened as well. Objective tests showed that the optimum bit rate distribution for mixed resolution stereo video coding is 30% to 35% of the total bit rate for the lower resolution view (half horizontal and half vertical). Finally, tests showed that mixed resolution stereo video decoding with up-sampling is less complex than decoding full resolution stereo video which is important for implementation on mobile devices.

Stereoscopic Displays and Applications XIX, 2008

We are interested in metrics for automatically predicting the compression settings for stereoscopic images so that we can minimize file size, but still maintain an acceptable level of image quality. Initially we investigate how Peak Signal to Noise Ratio (PSNR) measures the quality of varyingly coded stereoscopic image pairs. Our results suggest that symmetric, as opposed to asymmetric stereo image compression, will produce significantly better results. However, PSNR measures of image quality are widely criticized for correlating poorly with perceived visual quality. We therefore consider computational models of the Human Visual System (HVS) and describe the design and implementation of a new stereoscopic image quality metric. This point matches regions of high spatial frequency between the left and right views of the stereo pair and accounts for HVS sensitivity to contrast and luminance changes in regions of high spatial frequency, based on Michelson's Formula and Peli's Band Limited Contrast Algorithm. To establish a baseline for comparing our new metric with PSNR we ran a trial measuring stereoscopic image encoding quality with human subjects, using the Double Stimulus Continuous Quality Scale (DSCQS) from the ITU-R BT.500-11 recommendation. The results suggest that our new metric is a better predictor of human image quality preference than PSNR and could be used to predict a threshold compression level for stereoscopic image pairs.

2011 3DTV Conference: The True Vision - Capture, Transmission and Display of 3D Video (3DTV-CON), 2011

In mixed-resolution (MR) stereoscopic video, one view is presented with a lower resolution compared with the other one; therefore, a lower bitrate, a reduced computational complexity, and a decrease in memory access bandwidth can be expected in coding. The human visual system is known to fuse left and right views in such a way that the perceptual visual quality is closer to that of the higher-resolution view. In this paper, a subjective assessment of mixed resolution (MR) stereoscopic videos is presented and the results are analyzed and compared with previous subjective tests presented in the literature. Three downsampling ratios 1/2, 3/8, and 1/4 were used to create lower-resolution views. Hence, the lowerresolution view had different spatial resolutions in terms of pixels per degree (PPD) for each downsampling ratio. It was discovered that the subjective viewing experience tended to follow a logarithmic function of the spatial resolution of the lowerresolution view measured in PPD. A similar behavior was also found from the results of an earlier experiment. Thus, the results suggest that the presented logarithmic function characterizes the expected viewing experience of MR stereoscopic video.

2014 IEEE International Conference on Image Processing (ICIP), 2014

Asymmetric stereoscopic coding is a very promising technique to decrease the bandwidth required for stereoscopic 3D delivery. However, one large obstacle is linked to the limit of asymmetric coding or the just noticeable threshold of asymmetry, so that 3D viewing experience is not altered. By way of subjective experiments, recent works have attempted to identify this asymmetry threshold. However, fixed threshold, highly dependent on the experiment design, do not allow to adapt to quality and content variation of the image. In this paper, we propose a new non-uniform asymmetric stereoscopic coding adjusting in a dynamic manner the level of asymmetry for each image region to ensure unaltered binocular perception. This is achieved by exploiting several HVS-inspired models; specifically we used the Binocular Just Noticeable Difference (BJND) combined with visual saliency map and depth information to quantify precisely the asymmetry threshold. Simulation results show that the proposed method results in up to 44% of bitrate saving and provides better 3D visual quality compared to state-of-the-art asymmetric coding methods.

2017

Rate-distortion optimized layer selection is crucial for rate adaptation in scalable stereo video coding in order to achieve a higher degree of perceptual quality for a given rate. Quality Layers Optimization (QLO) and Trellis-based Optimization (TBO) are joint rate allocation methods in Scalable Multiview Video Coding (SMVC). But TBO is simpler alternative for real-time applications with one GoP delay. The binocular suppression theory leads the research towards asymmetric stereo video coding for 3D rate scaling. In scalable stereo video coding, it is possible to allocate the total bitrate between the two views symmetrically or asymmetrically through adaptive quality enhancement layer extraction. The contribution of the paper is two-fold: First, we propose asymmetric versions of the TBO algorithm. Second, subjective quality evaluation of TBO (symmetric and asymmetric) and QLO extraction methods are performed by using Single Stimulus Multi Media (SSMM) version of Subjective Evaluatio...

2007 3DTV Conference, 2007

This paper presents the results of the 3DTV quality evaluation on autostereoscopic displays using asymmetric view coding. Asymmetric view coding encodes the stereo views with different quality. It has been shown that the human visual system is able to compensate for this asymmetric view quality and present a good quality 3D video. Asymmetric video coding can be exploited to reduce the bandwidth requirements for 3DTV services. The key factors that affect the asymmetric video coding are the compression algorithms, the human visual system, and the 3D display. We conducted a subjective evaluation of 3D video with asymmetric view quality and encoded using MPEG-2. We also studied the impact of eye dominance on the perceived quality. We show that asymmetric view coding can be used to reduce the bandwidth requirements of 3DTV services based on MPEG-2 view coding.

2010

Abstract In mixed-resolution (MR) stereoscopic video, one of the views has a lower resolution compared to the other one, hence providing means for improved compression. The underlying assumption in MR stereoscopic video is that the human visual system fuses the left and right views in such a way that the perceived image quality is close to that of the higher-resolution view.

2016

The use of 3D stereoscopic technology with high quality videos can provide visual entertainment to viewers. However, the bandwidth of typical communication channels cannot transmit uncompressed 3D videos, resulting in the need for video quality compression. This paper presents a series of preliminary studies to investigate the subjective perception of uncompressed and compressed video sequences, and proposes the ‘hybrid’ sequencing of uncompressed and compressed content in a single stereoscopic 3D video as an alternative approach for limited bandwidth transmission. However, the hybrid uncompressed/compressed sequencing of stereoscopic 3D video may affect the correlation between the left and right views of the stereoscopic videos required for depth perception, potentially leading to lower Quality of Experience (QoE) of viewers. This paper therefore investigates both the objective and subjective quality evaluation of the proposed hybrid sequencing of stereoscopic video sequences. Init...