Effects of task experience and layout on learning from text and pictures with or without unnecessary picture descriptions

The presentation of extraneous (i.e., irrelevant or unnecessary) information may hamper learning with multimedia. The present study examined whether people can learn to ignore unnecessary information with increasing experience with the task and whether this depends on the layout of that information. In two experiments, participants learned about the process of mitosis from a multimedia slideshow, with each slide presenting a combination of expository text and a picture on one of the stages in the process. Slides either contained no unnecessary text (control condition) or unnecessary text (i.e., merely describing the picture) either integrated in the picture (integrated condition) or presented underneath the picture (separated condition). Knowledge about the studied mitosis phase was tested immediately after each slide using a cloze test. Across Experiments 1 and 2, we did not find a reliable negative effect of the unnecessary text on cloze test performance. As a result, the question of whether task experience would reduce or eliminate that negative effect could not be answered. The eye movement data did confirm, however, that participants attended less to the unnecessary information with increasing task experience, suggesting that students can adapt their study strategy and learn to ignore unnecessary information.     

准静止图象压缩编码及其在煤矿通信的应用

简要介绍准静止图象编码中的几种常用压缩编码方法：方块截断编码、分层编码、预测编码、并介绍一种煤矿井下视频信号的窄带传输系统，以此说明准静止图象压缩编码在煤矿中的应用。     

隐写术中的编码模型及方法研究

隐写术的目的是将秘密消息嵌入到多媒体数据中进行隐蔽传输。为了提高安全性,嵌入过程希望对载体做尽量少的修改并避免对敏感区的修改。这个数据嵌入问题可以用隐写码来解决。文章按照发送方拥有的边信息情况,将隐写编码问题分为三种模型：基本模型,湿纸模型和湿度级模型。对各种模型的下编码方法作了介绍,并以灰度图像上的±1隐写为例说明了隐写码可以大幅度提高隐写术的安全性。     

Depth-first picture expression viewed from digital picture processing

A picture coding strategy titled DF-expression (Depth-First picture expression) is now studied from another point of view. The basic idea of DF-expression is briefly reviewed at first. Its capability in data compression is demonstrated using 1024 × 1024 binary pictures. Then the new aspects of DF-expression are studied in reference to picture processing algorithm on the coded form. They include circular shiftings, spectrum of primitives, logical operations, etc. Application of DF-expression to gray images (or multivalued pictures) is the next topics of the paper. DF-expression is applicable to bit-plane coding of any binary image data. Our conclusion with this point is that the gray code is the best binary code system for DF-expression in information preserving sense. Information-lossy type data reduction is another topics in this paper. The authors propose a new data reduction technique in terms of uniformalization of excessively complicated regions in bit-planes. Experimental study follows using a 256 × 256 sized fourbit test picture. Finally, conclusions and other possibility of the applications are remarked.     

Event detection in real time on a personal camera phone image collection

Grouping photos of the same event together is extremely useful for the management of personal photo collections. However, most methods cannot be applied to the problem of online event detection in embedded devices because they do not consider hardware constraints or a user’s photo-taking behavior. In this paper, we propose an efficient and effective event detection algorithm for managing personal photo collections in camera phones or digital cameras. The proposed algorithm fuses time and location information, which is deemed the most important information for personal photo management, and works in real time in embedded devices. We model event occurrences in a user’s photo-taking behavior as a Poisson process by imposing certain constraints on calculating the elapsed time. Location information is incorporated into event detection when confidence in a decision based on the Poisson process is not high enough. The algorithm is user-centric because it provides the unique capabilities of accepting and adjusting to user feedback. Our experiment results show that the proposed event detection method has the potential to support emerging multimedia applications in embedded devices.     

CMOS在视频摄像器上的应用

比较了ＣＭＯＳ和ＣＣＤ技术在视频摄器领域中应用情况,重点描述了一种ＣＭＯＳ传感器的设计和制作。这种传感器的特点是在同一个芯片个集中大量的计算元件,形成传感器阵列,这样保证 探测的图像信息能够以直接满足多本计算机要求的形式输出。     

阶跃基权系数时变的预测函数控制

研究预测函数的精度优化问题,传统预测函数控制基函数为全局函数,过程预测轨迹与参考轨迹在预测时域内的拟合只有有限个拟合点,无法实现在整个预测时域内的整体优化目标.针对实际中无法实现全局拟合的情况,提出一种基函数进行加权来提高过程预测轨迹与参考轨迹逼近程度的新方法.根据参考轨迹的特点,采用阶跃基函数,其加权系数随着预测时步的增加而减小,在预测时域内使过程预测轨迹逼近参考轨迹,提高整体优化目标,减小了第一步预测控制量与理想控制量的差.每次控制量计算先进行基函数的权系数修正,保证过程预测轨迹与参考轨迹的尽可能全局拟合.上述预测函数控制策略用于某水厂混凝投药过程控制,在Matlab上仿真表明,具有更好的跟踪性和抗模型失配能力,比传统预测函数控制算法具有更好的控制效果.     

基于ADSP-BF533的多媒体通信终端设计与实现

采用ADSP BF533DSP处理器设计并实现了基于IP网路的多媒体通信终端系统。终端的管理采用μCOS II实时嵌入式操作系统。在分析μCOS II操作系统特点的基础上,把LwIP协议栈移植到μCOS II上实现了网络接口。试验结果表明,该系统在局域网中多媒体信息的编码、传输是实时的。     

多媒体电子邮件技术及其应用实例

多媒体电子邮件是一种综合了视频、音频、图像和文本的邮件形式。本文讨论了多媒体电子邮件的一些关键技术，包括其编码和信体格式。文中最后给出了其应用及制作实例。     

Predictive coding and the slowness principle: an information-theoretic approach

Understanding the guiding principles of sensory coding strategies is a main goal in computational neuroscience. Among others, the principles of predictive coding and slowness appear to capture aspects of sensory processing. Predictive coding postulates that sensory systems are adapted to the structure of their input signals such that information about future inputs is encoded. Slow feature analysis (SFA) is a method for extracting slowly varying components from quickly varying input signals, thereby learning temporally invariant features. Here, we use the information bottleneck method to state an information-theoretic objective function for temporally local predictive coding. We then show that the linear case of SFA can be interpreted as a variant of predictive coding that maximizes the mutual information between the current output of the system and the input signal in the next time step. This demonstrates that the slowness principle and predictive coding are intimately related.     

A new criterion using information gain for action selection strategy in reinforcement learning

In this paper, we regard the sequence of returns as outputs from a parametric compound source. Utilizing the fact that the coding rate of the source shows the amount of information about the return, we describe /spl lscr/-learning algorithms based on the predictive coding idea for estimating an expected information gain concerning future information and give a convergence proof of the information gain. Using the information gain, we propose the ratio /spl omega/ of return loss to information gain as a new criterion to be used in probabilistic action-selection strategies. In experimental results, we found that our /spl omega/-based strategy performs well compared with the conventional Q-based strategy.     

An on-line learning method for face association in personal photo collection

Due to the widespread use of cameras, it is very common to collect thousands of personal photos. A proper organization is needed to make the collection usable and to enable an easy photo retrieval. In this paper, we present a method to organize personal photo collections based on “who” is in the picture. Our method consists in detecting the faces in the photo sequence and arranging them in groups corresponding to the probable identities. This problem can be conveniently modeled as a multi-target visual tracking where a set of on-line trained classifiers is used to represent the identity models. In contrast to other works where clustering methods are used, our method relies on a probabilistic framework; it does not require any prior information about the number of different identities in the photo album. To enable future comparison, we present experimental results on a public dataset and on a photo collection generated from a public face dataset.     

H.264中基于上下文的参考帧选择算法

多参考帧选择技术提高了有暴露背景或新增景物区域的编码效率,但对视频编码性能的提升不大。该文提出基于上下文的多参考帧选择算法,利用宏块的运动特性决定当前宏块搜索的最大参考帧数目,通过分析当前参考帧预测的结果,动态地判断是否需要进行下一参考帧预测。实验结果表明,在编码质量接近全搜索算法的基础上,该算法搜索速度为全搜索算法的2.10倍~2.65倍。     

结合块旋转和马赛克拼图的生成式伪装方法

目的 搜索式无载体信息隐藏容量低,涉及大量载体密集传输;纹理合成无载体隐藏只能生成简单质地的纹理图像;马赛克拼图信息隐藏尽管能产生有意义图像,但需修改嵌入参数。针对以上问题,提出一种结合块旋转和马赛克拼图的生成式伪装方法。方法 将灰度图像进行圆形化并添加随机转角构建马赛克,通过随机坐标决定秘密信息的隐藏位置;在隐藏位置,根据密钥和放置位置来放置代表秘密比特串的圆形图像和施加认证转角,对于非隐藏位置则放置最接近圆形图像来掩盖秘密信息;将放置过程产生的偏差通过误差扩散分散给周围未处理像素。在提取时,结合质心旋转匹配提取秘密比特并进行转角认证。结果 采用圆形图像表达秘密信息而不涉及修改式嵌入,通过马赛克拼图产生有意义含密掩体,可通过质心旋转匹配提取秘密比特并进行转角认证。对密钥严格依赖,在遭受质量因子为50~80的JPEG压缩和随机转角攻击时,秘密信息可完整恢复,在遭受强度为8%~20%的椒盐噪声攻击时,提取信息的误码率低于5%,且对秘密信息的认证成功率均在80%以上。结论 所提方法具有较好的抗攻击能力,可抵御信道攻击且具备较高的安全性。     

浅析光盘教学资源在教学中的应用

随着计算机多媒体技术的发展,教学中运用的教材更加丰富起来,各种多媒体元素,如音频、视频、图像、动画等,这些多媒体元素所组成的教学信息所占的容量很大,一般的软磁盘是根本无法存储。所以只有存储在光盘上,才便于携带和长时间存放,而且其他存储器上的信息也可以转存到光盘上。转存是通过光盘刻录机来实现的。现在的刻录机越来越普及,价位也越来越低。可以说靠光盘来存储教学课件及其他教学数据资料是非常经济使用实用的。本文作者就身边光盘教学资源在教学中的应用,简单的谈一下的见解。     

基于静态串表的图像无损压缩编码方法

结合前像素预测编码方法和Lempel-Ziv-Welch(LZW)编码思想并针对其对于变化频率较高的信号压缩效率较低的问题,提出了一种通过利用图像像素之间相关性构建静态串表对数字图像进行无损压缩的编码方法。通过对前向预测编码处理后的图像数据进行查表编码来实现图像无损压缩。实验结果表明该方法实现简单,压缩效率高于LZW算法和WinZIP算法。     

Cross-Layer Packetization and Retransmission Strategies for Delay-Sensitive Wireless Multimedia Transmission

Existing wireless networks provide dynamically varying resources with only limited support for the quality of service required by the bandwidth-intense, loss-tolerant and delay-sensitive multimedia applications. This variability of resources does not significantly impact delay insensitive data transmission (e.g., file transfers), but has considerable consequences for multimedia applications. Recently, the research focus has been to adapt existing algorithms and protocols at the lower layers of the protocol stack to better support multimedia transmission applications and conversely, to modify application layer solutions to cope with the varying wireless networks resources. In this paper, we show that significant improvements in wireless multimedia performance can be obtained by deploying a joint application-layer adaptive packetization and prioritized scheduling and MAC-layer retransmission strategy. We deploy a state-of-the-art wavelet coder for the compression of the video data that enables on-the-fly adaptation to changing channel conditions and inherent prioritization of the video bitstream. We pose the cross-layer problem as a distortion minimization given delay constraints and derive analytical solutions by modifying existing joint source-channel coding theory aimed at fulfilling rate, rather than delay, constraints. We also propose real-time algorithms that explicitly consider the available information about previously transmitted packets. The obtained results show significant improvements in terms of video quality as opposed to ad-hoc optimizations currently deployed, while the complexity associated with performing this optimization in real time, i.e., at transmission time, is limited     

Geotagging in multimedia and computer vision—a survey

Geo-tagging is a fast-emerging trend in digital photography and community photo sharing. The presence of geographically relevant metadata with images and videos has opened up interesting research avenues within the multimedia and computer vision domains. In this paper, we survey geo-tagging related research within the context of multimedia and along three dimensions: (1) Modalities in which geographical information can be extracted, (2) Applications that can benefit from the use of geographical information, and (3) The interplay between modalities and applications. Our survey will introduce research problems and discuss significant approaches. We will discuss the nature of different modalities and lay out factors that are expected to govern the choices with respect to multimedia and vision applications. Finally, we discuss future research directions in this field.     

视频处理与压缩技术

视频处理与压缩是多媒体计算与通信领域的核心主题之一,是连接视频采集传输和视觉分析理解的关键桥梁,也是诸多视频应用的基础。当前“5G+超高清+AI”正在引发多媒体计算与通信领域的新一轮重大技术革新,视频处理与压缩技术正在发生深刻变革,亟需建立视频大数据高效紧凑表示理论和方法。为此,学术研究机构和工业界对视频大数据的视觉表示机理、视觉信息紧凑表达、视频信号重建与恢复、高层与低层视觉融合处理方法及相应硬件技术等前沿领域进行了广泛深入研究。本文从数字信号处理基础理论出发,分析了当前视频处理与压缩领域的热点问题和研究内容,包括基于统计先验模型的视频数据表示模型及处理方法、融合深度网络模型的视频处理技术、视频压缩技术以及视频压缩标准进展等领域。详细描述了视频超分辨率、视频重建与恢复、视频压缩技术等领域面临的前沿动态、发展趋势、技术瓶颈和标准化进程等内容,对国际国内研究内容和发展现状进行了综合对比与分析,并展望了视频处理与压缩技术的发展与演进方向。更高质量视觉效果和高效率视觉表达之间将不再是单独研究的个体,融合类脑视觉系统及编码机理的视频处理与压缩技术将是未来研究的重要领域之一。     

基于ROI的2D控制图像编码

图像是多媒体应用中人们相互之间进行信息交换的重要工具，它在Internet上实时可靠的传输对于多媒体应用的普及具有重要意义。然而，当图像在丢包网络如Internet上传输时，接收端有时需要经过长时间的等待才能获得整个码流来重建图像。为此提出了一种基于对象的精细可伸缩性编码方法，该方法将对象编码与位平面编码相结合。一方面，这种方法具有精细增强图像质量的能力；另一方面，它又可以通过指定对象优先级和提升位平面来更为灵活地控制用户感兴趣区(ROI，region of interest)。试验结果证明，该算法具有精细性和灵活控制性。