Anil Fernando

Sensitivity Analysis of the Human Visual System for Depth Cues in Stereoscopic 3-D Displays

Three-dimensional (3-D) displays provide a more realistic experience of entertainment by providing its viewers an added sensation of depth by artificially exploiting light rays to stimulate certain depth cues in the human visual system, especially binocular stereopsis. Due to its close relationship with human visual perception, mass market deployment of 3-D displays will be significantly dependant upon addressing the related perceptual factors such as visual comfort. In order to address the perceptual factors, it is very important to understand how humans experience depth on 3-D displays and how sensitive they are for different depth cues. In this paper, the sensitivity of humans for different depth cues is analyzed as applicable to 3-D viewing on stereoscopic displays. Mathematical models are derived to explain the just noticeable difference in depth (JNDD) for three different depth cues, namely binocular disparity, retinal blur, and relative size. Extensive subjective assessments are performed on a stereoscopic display with passive polarized glasses and on an auto-stereoscopic display to validate the mathematical models for JNDD. It is expected that the proposed models will have important use cases in 3-D display designing as well as 3-D content production.

Psycho-physical limits of interocular blur suppression and its application to asymmetric stereoscopic video delivery

It is well known that when the two eyes are provided with two views of different resolutions the overall perception is dominated by the high resolution view. This property, known as binocular suppression, is effectively used to reduce the bit rate required for stereoscopic video delivery, where one view of the stereo pair is encoded at a much lower quality than the other. There have been significant amount of effort in the recent past to measure the just noticeable level of asymmetry between the two views, where asymmetry is achieved by encoding views at two quantization levels. However, encoding artifacts introduce both blurring and blocking artifacts in to the stereo views, which are perceived differently by the human visual system. Therefore, in this paper, we design a set of psycho-physical experiments to measure the just noticeable level of asymmetric blur at various spatial frequencies, luminance contrasts and orientations. The subjective results suggest that humans could tolerate a significant amount of asymmetry introduced by blur, and the level of tolerance is independent of the spatial frequency or luminance contrast. Furthermore, the results of this paper illustrate that when asymmetry is introduced by unequal quantization, the just noticeable level of asymmetry is driven by the blocking artifacts. In general, stereoscopic asymmetry introduced by way of asymmetric blurring is preferred over asymmetric compression. It is expected that the subjective results of this paper will have important use cases in objective measurement of stereoscopic video quality and asymmetric compression and processing of stereoscopic video.

Efficient coding unit size selection based on texture analysis for HEVC intra prediction

Determining the best partitioning structure for a given Coding Tree Unit (CTU) is one of the most time consuming operations within the HEVC encoder. The brute force search through quadtree hierarchy has a significant impact on the encoding time of high definition (HD) videos. This paper presents a fast coding unit size decision-taking algorithm for intra prediction in HEVC. The proposed algorithm utilizes a low complex texture analysis technique based on the local range property of a pixel in a given neighborhood. Simulation results show that the proposed algorithm achieves an average of 72.24% encoding time efficiency improvement with similar rate distortion performance compared to HEVC reference software HM12.0 for HD videos.

A new reduced reference metric for color plus depth 3D video

A new reduced reference (RR) objective quality metric for 3D video is proposed that incorporates spatial neighboring information. The contrast measures from gray level co-occurrence matrices (GLCM) for both color and depth sections are main parts of spatial information. Side information is extracted from edge properties of reference 3D video and sent through an auxiliary channel. The other important factor in the proposed metric is the unequal weight of color and depth sections, which can maximize the performance of the proposed metric for some specific values. Performance of the proposed metric is validated through series of subjective tests. For validations, compression and transmission artifacts are considered. The average correlation of the proposed metric and subjective quality scores is 0.82 for compressed 3D videos when color to depth importance ratio is near 0.8. This measure for transmitted 3D videos is 0.857 for the same value of color to depth importance ratio.

Prediction of DoS attacks in external communication for self-driving vehicles using a fuzzy petri net model

In this paper we propose a security system to protect external communications for self-driving and semi self-driving cars. The proposed system can detect malicious vehicles in an urban mobility scenario. The anomaly detection system is based on fuzzy petri nets (FPN) to detect packet dropping attacks in vehicular ad hoc networks. The experimental results show the proposed FPN-IDS can successfully detect DoS attacks in external communication of self-driving vehicles.

QoE aware resource allocation for video communications over LTE based mobile networks

As the limits of video compression and usable wireless radio resources are exhausted, providing increased protection to critical data is regarded as a way forward to increase the effective capacity for delivering video data. This paper explores the provisioning of selective protection in the physical layer to critical video data and evaluates its effectiveness when transmitted through a wireless multipath fading channel. In this paper, the transmission of HEVC encoded video through an LTE-A wireless channel is considered. HEVC encoded video data is ranked based on how often each area of the picture is referenced by subsequent frames within a GOP in the sequence. The critical video data is allotted to the most robust OFDM resource blocks (RBs), which are the radio resources in the time-frequency domain of the LTE-A physical layer, to provide superior protection. The RBs are ranked based on a prediction for their robustness against noise. Simulation results show that the proposed content aware resource allocation scheme helps to improve the objective video quality up to 37dB at lower channel SNR levels when compared against the reference system, which treats video data uniformly. Alternatively, with the proposed technique the transmitted signal power can be lowered by 30% without sacrificing video quality at the receiver.

Depth Based Perceptual Quality Assessment for Synthesised Camera Viewpoints

This paper considers the visual quality assessment for view synthesis in the context of 3D video delivery chain. It is targeted to perceptually quantify the reconstruction quality of synthesised camera viewpoints. It is needed for developing better QoE models related to 3D-TV, as well as for a better representation of the effect of depth maps on views synthesis quality. In this paper, existing 2D video quality assessment methods, like PSNR and SSIM, are extended to assess the perceived quality of synthesised viewpoints based on the depth range. The performance of the extended assessment techniques is measured by correlating multiple sample video assessment scores to that of the Video Quality Metric (VQM) scores, which are a robust reflector of real subjective opinions.

Modelling the Interface Pressure Applied by Knitted Structures Designed for Medical-textile Applications

A theoretical model is proposed for prediction of the interface-pressure profile applied by plain-knitted elastomeric structures used in compression therapy. Compression therapy may be applied through pressure garments to prevent and reduce venous reflux and peripheral oedema. The interface pressure induced by a compression garment is defined by Laplaces equation, and the geometrical and mechanical behaviour of knitted structures is modelled to predict interface pressure. The geometrical mesostructure is modelled by parametric cubic-spline curves, and the mechanical system is modelled on energy-based principles. The model incorporates all possible mechanisms of deformation, including elongation, bending, compression, and volume changes of the yarns. The theoretical predictions are compared with experimental pressure profiles for four different radii of curvature.

Adaptive residual mapping for an efficient extension layer coding in two-layer HDR video coding

In the absence of a commercial High Dynamic Range (HDR) distribution pipeline, two-layer backward-compatible HDR video coding is a viable solution for the imminent transition from Low Dynamic Range (LDR) to HDR content transmission. However, the performance of a two-layer coding solution is governed by the extension layer coding performance. In this paper, we propose an improved two-layer backward-compatible HDR video coding solution based on an adaptive residual mapping for the extension layer, keeping in view the performance of High Efficiency Video Coding (HEVC) being used to code this information. The proposed solution outperforms the reference method achieving averaged PU-PSNR improvements of up to 5.05 dB. The proposed method also shows potential of achieving the same HDR quality as the single layer coding solution with a minimum bitrate overhead and acceptable LDR quality in the base layer.

Perceptual QoE based resource allocation for mobile 3D video communications

This paper suggests a power and bandwidth efficient resource allocation approach for mobile networks based on consumers perception of 3D video. We simulate a mobile 3D video transmission through which we identify the correlation between receivers signal-to-noise ratio and perceived quality. Our QoE-based approach is shown to save up to 33.13% in power and grant up to 50% more data bits for transmission, compared to QoS-based techniques.