W.A.C. Fernando

Quality analysis for 3D video using 2D video quality models

The 3D (3-dimensional) video technologies are emerging to provide more immersive media content compared to conventional 2D (2-dimensional) video applications. More often 3D video quality is measured using rigorous and time-consuming subjective evaluation test campaigns. This is due to the fact that 3D video quality can be described as a combination of several perceptual attributes such as overall image quality, perceived depth, presence, naturalness and eye strain, etc. Hence this paper investigates the relationship between subjective quality measures and several objective quality measures like PSNR, SSIM, and VQM for 3D video content. The 3D video content captured using both stereo camera pair (two cameras for left and right views) and colour-and-depth special range cameras are considered in this study. The results show that, VQM quality measures of individual left and right views (rendered left and right views for colour-and-depth sequences) can be effectively used in predicting the overall image quality and statistical measures like PSNR and SSIM of left and right views illustrate good correlations with depth perception of 3D video.

Fade and dissolve detection in uncompressed and compressed video sequences

Automatic identification of special effects is a prerequisite for video indexing and intelligent video encoding. In this paper we present an algorithm for fade and dissolve scene change detection in video sequences. We use statistical features of the images to identify these special effects in uncompressed video. DC-estimation is used to evaluate statistical features both in H.263 and MPEG-2 compressed video. Results show that these special effects can be identified accurately with the proposed scheme.

Adaptive modulation based MC-CDMA systems for 4G wireless consumer applications

Adaptive modulation based MC-CDMA systems can play a vital role in future generation consumer communication electronics. Adaptive modulation, combined with MC-CDMA based transmission technology, is a promising way to increase the data rate that can be reliably transmitted over the wireless radio channels. For 4G wireless networks, which demand very high data rate up to 100 Mbits/s with the constraints limiting higher data rate being severe ISI due to multipath and limited spectrum, such kind of adaptive modulation based multi-carrier systems applied to a wide-area environment, can achieve very large average user throughputs. In this paper, adaptive modulation based M-ary PSK, M-ary QAM, M-ary CPM, M-ary MHPM and GMSK systems applied to a turbo coded MC-CDMA system in a Rayleigh fast fading channel environment have been investigated and the BER performance of all these digital modulation techniques have been compared. Results of the comparative study indicate that the continuous phase modulation schemes like CPM, MHPM, and GMSK gives better performance as compared to PSK and QAM schemes. At most of the time, the MHPM systems outperforms both GMSK and CPM. The PSK and QAM based systems perform well till the number of users are around 10. As a whole, the adaptive MHPM system is found to give the optimum performance among the considered digital modulation schemes for the MC-CDMA system in a 4G environment.

Perceptual Video Quality Metric for 3D video quality assessment

One method of evaluating the quality of stereoscopic video is the use of conventional two dimensional (2D) objective metrics. Metrics with good representation of the Human Visual System (HVS) will present more accurate evaluation. In this paper we propose a perceptual based objective metric for 2D videos for 3D video quality evaluation. The proposed Perceptual Quality Metric (PQM) shows better results for 3D video quality evaluation and outperforms the Video Quality Metric (VQM); as it is sensitive to slight changes in image degradation and error quantification starts at pixel level right up to the sequence level. Verifications are done through series of subjective tests to show the level of correlation of PQM and user scores.

A unified approach to scene change detection in uncompressed and compressed video

There is an urgent need to extract key information automatically from video for the purposes of indexing, fast retrieval and scene analysis. To support this vision, reliable scene change detection algorithms must be developed. This paper describes a novel unified algorithm for scene change detection in uncompressed and MPEG-2 compressed video sequences using statistical features of images. Results on video of various content types are reported and validated with the proposed scheme in uncompressed and MPEG-2 compressed video. Furthermore, results show that the accuracy of the detected transitions is above 95% and 90% for uncompressed and MPEG-2 compressed video respectively.

3D motion estimation for depth image coding in 3D video coding

In this paper, a new solution is introduced for the efficient compression of 3D video based on color and depth maps. While standard video codecs are designed for coding monoscopic videos, their application to depth maps is found to be suboptimal. With regard to the special properties of the depth maps, we propose an extension to conventional video coding in order to take advantage of object motion in the depth direction. Instead of performing a 2D motion search, as is common in conventional video codecs, we propose the use of a 3D motion search that is able to better exploit the temporal correlations of 3D content. In this new framework, the motion of blocks in depth maps are described using 3D motion vectors (x, y, z), representing the horizontal, vertical, and depth directions respectively. This leads to more accurate motion prediction and a smaller residual. The experimental results show that the proposed technique delivers an improvement in motion compensation, which leads to gains in compression efficiency.

Display Dependent Preprocessing of Depth Maps Based on Just Noticeable Depth Difference Modeling

This paper addresses the sensitivity of human vision to spatial depth variations in a 3-D video scene, seen on a stereoscopic display, based on an experimental derivation of a just noticeable depth difference (JNDD) model. The main target is to exploit the depth perception sensitivity of humans in suppressing the unnecessary spatial depth details, hence reducing the transmission overhead allocated to depth maps. Based on the JNDD model derived, depth map sequences are preprocessed to suppress the depth details that are not perceivable by the viewers and to minimize the rendering artefacts that arise due to optical noise, where the optical noise is triggered by the inaccuracies in the depth estimation process. Theoretical and experimental evidences are provided to illustrate that the proposed depth adaptive preprocessing filter does not alter the 3-D visual quality or the view synthesis quality for free-viewpoint video applications. Experimental results suggest that the bit rate for depth map coding can be reduced up to 78% for the depth maps captured with depth-range cameras and up to 24% for the depth maps estimated with computer vision algorithms, without affecting the 3-D visual quality or the arbitrary view synthesis quality.

An Iterative Refinement Technique for Side Information Generation in DVC

Distributed video coding (DVC) is an increasingly popular approach among the researchers in video coding during past few years due to its attractive and promising features. In DVC, the majority of the computational complexity has been shifted from encoder to the decoder in comparison to its conventional counterparts, including MPEG and H.26 x enabling a dramatically low cost encoder implementation. Side information generation, carried out at the decoder, is a major function in the DVC coding algorithm and plays a key-role in determining the performance of the codec. In this paper, a novel iterative refinement technique is proposed for the side information generation process. Simulation results of the proposed technique depict a consistent improvement in performance in comparison to the state-of-the-art in pixel domain DVC.

Unequal Error Protection Technique for ROI Based H.264 Video Coding

This paper presents a region of interest (ROI) based video coding technique for H.264 based video coding with improved error resilience and error protection in the foreground. We used the flexible macroblock ordering (FMO) tool in H.264 video coding standard to encode the video frame into three separate slices. First slice carries the background, and other two slices contains alternative macroblock of the foreground forming a check board pattern. Foreground packets are protected with a stronger error correction code than background packets. Experimental results show that the proposed technique improves the objective quality of the foreground by more than 1 dB

Object based coding of the depth maps for 3D video coding

The emergence of three dimensional (3D) video applications, based on depth image based rendering (DIBR) has brought up more requirements of bandwidth, due to the need of depth information. This additional bandwidth requirement need to be tackled to enable the widespread of 3D video applications based on DIBR. Exploiting visual correlations between the color image and the depth image, in depth image coding, will reduce the requirement of high bandwidth required to transmit the additional depth information. In this paper, an object based depth image coding technique is presented which is suitable for low bit rate 3D-TV applications that are based on depth image based rendering. The proposed method achieves at most 50% bit rate reduction at low bit rates.