New Method for Temporal Information Detection of Video Quality Assessment

针对视频质量评测中时域信息的检测方法,本文提出了新的计算方法。该方法根据AnSI T1.801.03-1996和ITu-T rECOMMEndATIOn P.910时域信息(TI)的概念定义和方法推荐,采用先对时域梯度图求直方图,再在所求直方图的基础上进行统计计算的方式,克服了直接进行时域梯度rMS计算带来的乘法运算量与画面像素数成正比从而导致耗时较多的缺陷。实验结果表明,采用本改进方式的乘法运算量仅取决于直方图的灰度级,而与具体像素数无关,在同等条件下的平均计算效率可提高约三倍,且对时域信息的检测效果与推荐方法相仿。该方法实现简单,易于集成,在视频质量评测应用中具有较好的推广价值。Concerning about the Temporal Information(TI) detection for video quality assessment,a new method is proposed based on the definition and algorithm recommended by the ANSI T1.801.03-1996 and ITU-T Recommendation P.910.At first,image of the temporal derivative would be changed into the histogram domain,and then the statistic calculation(RMS and so on) was done for the temporal information.The drawback of the conventional method was overcome whose workload would increase greatly with the increase of the number of the pixel in scene image.Experimental results show that the computation complexity is dependent on the gray level of histogram,but is independent of the number of the pixel by the new method.In the same experiment condition,the computational efficiency is improved three times while the performance is similar to the conventional method.The algorithm is so simple and feasible that it could be used for the application of video quality assessment.福建省自然科学基金青年科技人才创新资助项目(2009J05154

Educational Handheld Video: Examining Shot Composition, Graphic Design, And Their Impact On Learning

Formal features of video such as shot composition and graphic design can weigh heavily on the success or failure of educational videos. Many studies have assessed the proper use of these techniques given the psychological expectations that viewers have for video programming (Hawkins et al., 2002; Kenny, 2002; Lang, Zhou, Schwardtz, Bolls, & Potter, 2000; McCain, Chilberg, & Wakshlag, 1977; McCain & Repensky, 1972; Miller, 2005; Morris, 1984; Roe, 1998; Schmitt, Anderson, & Collins, 1999; Sherman & Etling, 1991; Tannenbaum & Fosdick, 1960; Wagner, 1953). This study examined formal features within the context of the newly emerging distribution method of viewing video productions on mobile handheld devices. Shot composition and graphic design were examined in the context of an educational video to measure whether or not they had any influence on user perceptions of learning and learning outcomes. The two formal features were modified for display on 24 inch screens and on 3.5 inch or smaller screens. Participants were shown one of the four modified treatments, then presented with a test to measure whether or not the modified formal features had any impact or influence on learning outcomes from a sample of 132 undergraduate college students. No significant differences were found to occur as a result of manipulation of formal features between the treatment groups

A new video quality metric for compressed video.

Video compression enables multimedia applications such as mobile video messaging and streaming, video conferencing and more recently online social video interactions to be possible. Since most multimedia applications are meant for the human observer, measuring perceived video quality during the designing and testing of these applications is important. Performance of existing perceptual video quality measurement techniques is limited due to poor correlation with subjective quality and implementation complexity. Therefore, this thesis presents new techniques for measuring perceived quality of compressed multimedia video using computationally simple and efficient algorithms. A new full reference perceptual video quality metric called the MOSp metric for measuring subjective quality of multimedia video sequences compressed using block-based video coding algorithms is developed. The metric predicts subjective quality of compressed video using the mean squared error between original and compressed sequences, and video content. Factors which influence the visibility of compression-induced distortion such as spatial texture masking, temporal masking and cognition, are considered for quantifying video content. The MOSp metric is simple to implement and can be integrated into block-based video coding algorithms for real time quality estimations. Performance results presented for a variety of multimedia content compressed to a large range of bitrates show that the metric has high correlation with subjective quality and performs better than popular video quality metrics. As an application of the MOSp metric to perceptual video coding, a new MOSpbased mode selection algorithm for a H264/AVC video encoder is developed. Results show that, by integrating the MOSp metric into the mode selection process, it is possible to make coding decisions based on estimated visual quality rather than mathematical error measures and to achieve visual quality gain in content that is identified as visually important by the MOSp metric. The novel algorithms developed in this research work are particularly useful for integrating into block based video encoders such as the H264/AVC standard for making real time visual quality estimations and coding decisions based on estimated visual quality rather than the currently used mathematical error measures

Gradient-based image and video quality assessment

У овој дисертацији разматране су објективне мере процене квалитета слике и видеа са потпуним и делимичним референцирањем на изворни сигнал. За потребе евалуације квалитета развијене су поуздане, рачунски ефикасне мере, засноване на очувању информација о градијенту. Мере су тестиране на великом броју тест слика и видео секвенци, различитих типова и степена деградације. Поред јавно доступних база слика и видео секвенци, за потребе истраживања формиране су и нове базе видео секвенци са преко 300 релевантних тест узорака. Поређењем доступних субјективних и објективних скорова квалитета показано је да је објективна евалуација квалитета веома сложен проблем, али га је могуће решити и доћи до високих перформанси коришћењем предложених мера процене квалитета слике и видеа.U ovoj disertaciji razmatrane su objektivne mere procene kvaliteta slike i videa sa potpunim i delimičnim referenciranjem na izvorni signal. Za potrebe evaluacije kvaliteta razvijene su pouzdane, računski efikasne mere, zasnovane na očuvanju informacija o gradijentu. Mere su testirane na velikom broju test slika i video sekvenci, različitih tipova i stepena degradacije. Pored javno dostupnih baza slika i video sekvenci, za potrebe istraživanja formirane su i nove baze video sekvenci sa preko 300 relevantnih test uzoraka. Poređenjem dostupnih subjektivnih i objektivnih skorova kvaliteta pokazano je da je objektivna evaluacija kvaliteta veoma složen problem, ali ga je moguće rešiti i doći do visokih performansi korišćenjem predloženih mera procene kvaliteta slike i videa.This thesis presents an investigation into objective image and video quality assessment with full and reduced reference on original (source) signal. For quality evaluation purposes, reliable, computational efficient, gradient-based measures are developed. Proposed measures are tested on different image and video datasets, with various types of distorsions and degradation levels. Along with publicly available image and video quality datasets, new video quality datasets are maded, with more than 300 relevant test samples. Through comparison between available subjective and objective quality scores it has been shown that objective quality evaluation is highly complex problem, but it is possible to resolve it and acchieve high performance using proposed quality measures