Lightness Change as Perceived in Relation to the Size of Recognized Visual Space of Illumination

According to the concept of the recognized visual space of illumination (RVSI) the lightness of an object surface is perceived in relation to its conceptualized size. To prove this proposition the lightness of gray test patches was judged when they were located at various positions inside an illuminated space composed of two rooms in the depth direction from a subject. No retinal image arrangement was changed in the test patch and its immediate surroundings, but the front room had walls, floors and furniture lower in lightness by the amount of N1.5 than the back room to make the RVSI of the former smaller despite the illuminance in the entire space being the same. The results showed that the apparent lightness of the patches was perceived higher by amount of about 13 in L units for the N4 test patch and about 20 for N6 when the patches were located in the front room, in accordance with the prediction. It was stressed that the experiment of lightness judgment should be conducted in a three dimensional space rather than two dimensional plane as done by several investigators.     

A weighted full-reference image quality assessment based on visual saliency

In full reference image quality assessment (IQA), the images without distortion are usually employed as reference, while the structures in both reference images and distorted images are ignored and all pixels are equally treated. In addition, the role of human visual system (HVS) is not taken account into subjective IQA metric. In this paper, a weighted full-reference image quality metric is proposed, where a weight imposed on each pixel indicates its importance in IQA. Furthermore, the weights can be estimated via visual saliency computation, which can approximate the subjective IQA via exploiting the HVS. In the experiments, the proposed metric is compared with several objective IQA metrics on LIVE release 2 and TID 2008 database. The results demonstrate that SROCC and PLCC of the proposed metric are 0.9647 and 0.9721, respectively,which are higher than other methods and it only takes 427.5 s, which is lower than that of most other methods.     

视频传感器网络中面向特定场景的行人检测方法(英文)

Pedestrian detection is one of the most important problems in the visual sensor network. Considering that the visual sensors have limited cap ability, we propose a pedestrian detection method with low energy consumption. Our method contains two parts: one is an Enhanced Self-Organizing Background Subtraction (ESOBS) based foreground segmentation module to obtain active areas in the observed region from the visual sensors; the other is an appearance model based detection module to detect the pedestrians from the foreground areas. Moreover, we create our own large pedestrian dataset according to the specific scene in the visual sensor network. Numerous experiments are conducted in both indoor and outdoor specific scenes. The experimental results show that our method is effective.     

基于人类视觉的快速自动调焦法

为了提高自动调焦算法的性能,对调焦评价函数和调焦搜索算法进行了研究。在分析人类视觉系统(HVS)特性研究成果的基础上,提出了一种基于HVS加权的小波调焦评价函数。根据视觉多通道特性和视觉敏感度带通特性,对不同方向、不同空间频带的小波高频系数分别赋予不同的权值。为了克服爬山法搜索速度慢的缺点,提出了一种基于SOM神经网络的搜索算法,采用训练完成的SOM神经网络预测镜头的最佳聚焦位置。实验结果表明,提出的小波调焦评价函数得到了比传统小波调焦评价函数更优的调焦特性曲线;采用本文的搜索算法平均仅需要采集处理7.3幅图像就能找到最佳聚焦位置,与基于全搜索的爬山法相比,节省了大量的搜索时间。说明提出的调焦方法不但可以得到符合人眼视觉的调焦效果,还可以实现快速自动调焦。     

频域图像数字水印技术

数字水印技术作为一种新型的数据隐藏技术,它通过在宿主数字媒体中嵌入一定的数字信息,实现数字产品的版权保护、安全传输等作用。本文在介绍水印技术的基本要求之后,重点讨论几种典型的数字水印嵌入和检测算法。     

PSTN网上可视多媒体通信终端

介绍了符合ＩＴＵ－ＴＨ．３２４协议的ＰＳＴＮ网上可视多媒体通信终端——ＫＤＭＭＴ。它在外接符合Ｖ．３４的调制解调器时,能通过ＰＳＴＮ网全双工实时传送图像和声音;介绍了终端系统的软硬件结构,高效实现音频和视频压缩编解码算法的关键技术以及系统互连时相关通信协议的设计与实现。     

3D视频的质量损伤类型分析

首先介绍了3D视频通信系统和人类视觉系统,然后通过结构、颜色、运动和深度的4个视觉子系统,分析每个通信模块中各类立体质量损伤的现象、成因和解决办法.立体损伤与设备、表示方式、编解码算法以及主观感知等多重因素有关,了解质量损伤的类型有助于质量评价工作的进行,进而对系统的其他环节做出优化.     

No-Reference Video Quality Assessment using novel hybrid features and two-stage hybrid regression for score level fusion

This paper presents a novel No-Reference Video Quality Assessment (NR-VQA) model that utilizes proposed 3D steerable wavelet transform-based Natural Video Statistics (NVS) features as well as human perceptual features. Additionally, we proposed a novel two-stage regression scheme that significantly improves the overall performance of quality estimation. In the first stage, transform-based NVS and human perceptual features are separately passed through the proposed hybrid regression scheme: Support Vector Regression (SVR) followed by Polynomial curve fitting. The two visual quality scores predicted from the first stage are then used as features for the similar second stage. This predicts the final quality scores of distorted videos by achieving score level fusion. Extensive experiments were conducted using five authentic and four synthetic distortion databases. Experimental results demonstrate that the proposed method outperforms other published state-of-the-art benchmark methods on synthetic distortion databases and is among the top performers on authentic distortion databases. The source code is available at https://github.com/anishVNIT/two-stage-vqa.     

基于FPGA的数字视频异步帧频转换器设计

利用DVI接口的同步控制信号生成内存写入地址,帧频触发信号控制内存读取地址的设计思想,在FPGA中实现了从任意帧频的数字视频源转换到50 Hz或60 Hz帧频.给出了帧频转换器的基本硬件结构,和实用的设计方法,并讨论了数据缓冲区设置深度与内存操作带宽的关系.