初级视觉信息处理机理与多分辨分析

详细阐述了初级视觉信息处理的生理过程,并将其信息处理机制与多分辨分析方法对应起来,提出了基于小波的计算机初级视觉信息处理机制.     

面像识别中的图像处理研究

本文以面像识别技术的核心——数字图像处理着手,以基于计算机视觉公开函数库为基础,着重讨论了面像识别的图像处理方法,以及这些方法处理的效果.     

Feature-based attention influences motion processing gain in macaque visual cortex.

Changes in neural responses based on spatial attention have been demonstrated in many areas of visual cortex, indicating that the neural correlate of attention is an enhanced response to stimuli at an attended location and reduced responses to stimuli elsewhere. Here we demonstrate non-spatial, feature-based attentional modulation of visual motion processing, and show that attention increases the gain of direction-selective neurons in visual cortical area MT without narrowing the direction-tuning curves. These findings place important constraints on the neural mechanisms of attention and we propose to unify the effects of spatial location, direction of motion and other features of the attended stimuli in a 'feature similarity gain model' of attention.     

Neuronal properties underlying processing of visual information in the barnacle.

Generation of a transient, amplified response to the dimming of light in the visual system of the barnacle involves two synaptic stages. It is accomplished primarily by decrementally conducting neurones that are similar to bipolar cells of the vertebrate retina.     

Serial and parallel processing of visual feature conjunctions

Treisman and others have reported that the visual search for a target distinguished along a single stimulus dimension (for example, colour or shape) is conducted in parallel, whereas the search for an item defined by the conjunction of two stimulus dimensions is conducted serially. For a single dimension the target 'pops out' and the search time is independent of the number of irrelevant items in the set. For conjunctions, the search time increases as the set becomes larger. Thus, it seems that the visual system is incapable of conducting a parallel search over two stimulus dimensions simultaneously. Here we extend this conclusion for the conjunction of motion and colour, showing that it requires a serial search. We also report two exceptions: if one of the dimensions in a conjunctive search is stereoscopic disparity, a second dimension of either colour or motion can be searched in parallel.     

Segregation of global and local motion processing in primate middle temporal visual area.

The early stages of primate visual processing appear to be divided up into several component parts so that, for example, colour, form and motion are analysed by anatomically distinct streams. We have found that further subspecialization occurs within the motion processing stream. Neurons representing two different kinds of information about visual motion are segregated in columnar fashion within the middle temporal area of the owl monkey. These columns can be distinguished by labelling with 2-deoxyglucose in response to large-field random-dot patterns. Neurons in lightly labelled interbands have receptive fields with antagonistic surrounds: the response to a centrally placed moving stimulus is suppressed by motion in the surround. Neurons in more densely labelled bands have surrounds that reinforce the centre response so that they integrate motion cues over large areas of the visual field. Interband cells carry information about local motion contrast that may be used to detect motion boundaries or to indicate retinal slip during visual tracking. Band cells encode information about global motion that might be useful for orienting the animal in its environment.     

基于OpenCV的人脸图像预处理技术研究

对采集到的人脸图像进行预处理和训练,以改善图像的视觉效果,提高图像的清晰度,并且使图像更有利于计算机处理,便于对图像进行分割和边缘检测,从而提高人脸图像人别的准确率,为人脸的提取特征值和识别等操作做好准备.利用PCA人脸识别方法,实现简单且识别准确率高,OpenCV的特点是实现了图像处理和计算机视觉方面的很多通用算法,实验结果表明,通过预处理后的人脸图像识别效果更好,识别速度更快.     

Perceptual consequences of centre-surround antagonism in visual motion processing

Centre-surround receptive field organization is a ubiquitous property in mammalian visual systems, presumably tailored for extracting image features that are differentially distributed over space. In visual motion, this is evident as antagonistic interactions between centre and surround regions of the receptive fields of many direction-selective neurons in visual cortex. In a series of psychophysical experiments we make the counterintuitive observation that increasing the size of a high-contrast moving pattern renders its direction of motion more difficult to perceive and reduces its effectiveness as an adaptation stimulus. We propose that this is a perceptual correlate of centre-surround antagonism, possibly within a population of neurons in the middle temporal visual area. The spatial antagonism of motion signals observed at high contrast gives way to spatial summation as contrast decreases. Evidently, integration of motion signals over space depends crucially on the visibility of those signals, thereby allowing the visual system to register motion information efficiently and adaptively.     

基于视觉词袋模型的图像信息处理算法研究

研究一种基于视觉词袋模型的图像筛选与搜索优化算法以提高机器人闭环检测质量和降低图像信息处理量.首先,通过SURF算子提取图像中的特征信息,构建对应的视觉词袋模型,并形成视觉词袋直方图;其次,基于视觉词袋直方图计算获得对应的图像混合显著度,进而筛选出信息量丰富且可区分度大的图像,并组成待搜索图像集合;然后,从视觉词袋直方图中提取图像中的显著主要特征类组成集合,并用其近似替代图像的特征分布情况,以降低图像特征信息处理量,加快图像搜索速度.最后,仿真实验证明本文提出的图像筛选和搜索方法的可行性和有效性.     

A study on neural mechanism of face processing based on fMRI

Recently, there were debates about the specificity of lateral middle fuisform in face processing. The debates focused on whether these areas were specialized in face processing or involved in processing of visual expertise and categorization at individual level. The present study aims to investigate the neural mechanism of face processing, using Chinese characters as comparison stimuli. Chinese characters are greatly similar to faces on a variety of dimensions, among which the most significant one is that both faces and Chinese characters not only are extremely familiar to literate Chinese adults but also are processed at individual level. In the present study, faces and Chinese characters activated bilateral middle fusiform with great correlation. Greater activities were observed in the right fusiform face area (FFA) for faces than for Chinese characters. These results demonstrate that FFA is specialized in face processing per se rather than the processing of visual expertise and categorization at individual level.     

A study on neural mechanism of face processing based on fMRI

Recently, there were debates about the specificity of lateral middle fusiform in face processing. The debates focused on whether these areas were specialized in face processing or involved in processing of visual expertise and categorization at individual level. The present study aims to investigate the neural mechanism of face processing, using Chinese characters as comparison stimuli. Chinese characters are greatly similar to faces on a variety of dimensions, among which the most significant one is that both faces and Chinese characters not only are extremely familiar to literate Chinese adults but also are processed at individual level. In the present study, faces and Chinese characters activated bilateral middle fusiform with great correlation. Greater activities were observed in the right fusiform face area （FFA） for faces than for Chinese characters. These results demonstrate that FFA is specialized in face processing per se rather than the processing of visual expertise and categorization at individual level.     

The contribution of sensory experience to the maturation of orientation selectivity in ferret visual cortex.

Sensory experience begins when neural circuits in the cerebral cortex are still immature; however, the contribution of experience to cortical maturation remains unclear. In the visual cortex, the selectivity of neurons for oriented stimuli at the time of eye opening is poor and increases dramatically after the onset of visual experience. Here we investigate whether visual experience has a significant role in the maturation of orientation selectivity and underlying cortical circuits using two forms of deprivation: dark rearing, which completely eliminates experience, and binocular lid suture, which alters the pattern of sensory driven activity. Orientation maps were present in dark-reared ferrets, but fully mature levels of tuning were never attained. In contrast, only rudimentary levels of orientation selectivity were observed in lid-sutured ferrets. Despite these differences, horizontal connections in both groups were less extensive and less clustered than normal, suggesting that long-range cortical processing is not essential for the expression of orientation selectivity, but may be needed for the full maturation of tuning. Thus, experience is beneficial or highly detrimental to cortical maturation, depending on the pattern of sensory driven activity.     

潘军早期小说的两类艺术建构

小说创作史上的两类作家经验型与超验型,潘军小说在经验世界与超验世界"双轨"推进.以<日晕>为代表,作者塑造了官场人物群、知识分子人物群、乡土人物群,建构了与现实对应性很强的经验世界.而<省略>等中篇小说,以象征的手法,从本质上展示了人与人关系的异化,从本体论上进行概括抽象的思考.而其形式上的探索所体现出来的精神意蕴--希望有一种健全理想的人与人和睦相处的关系存在,正是潘军艺术创作的恒性品格所在.     

Influence of the thalamus on spatial visual processing in frontal cortex

Each of our movements activates our own sensory receptors, and therefore keeping track of self-movement is a necessary part of analysing sensory input. One way in which the brain keeps track of self-movement is by monitoring an internal copy, or corollary discharge, of motor commands. This concept could explain why we perceive a stable visual world despite our frequent quick, or saccadic, eye movements: corollary discharge about each saccade would permit the visual system to ignore saccade-induced visual changes. The critical missing link has been the connection between corollary discharge and visual processing. Here we show that such a link is formed by a corollary discharge from the thalamus that targets the frontal cortex. In the thalamus, neurons in the mediodorsal nucleus relay a corollary discharge of saccades from the midbrain superior colliculus to the cortical frontal eye field. In the frontal eye field, neurons use corollary discharge to shift their visual receptive fields spatially before saccades. We tested the hypothesis that these two components-a pathway for corollary discharge and neurons with shifting receptive fields-form a circuit in which the corollary discharge drives the shift. First we showed that the known spatial and temporal properties of the corollary discharge predict the dynamic changes in spatial visual processing of cortical neurons when saccades are made. Then we moved from this correlation to causation by isolating single cortical neurons and showing that their spatial visual processing is impaired when corollary discharge from the thalamus is interrupted. Thus the visual processing of frontal neurons is spatiotemporally matched with, and functionally dependent on, corollary discharge input from the thalamus. These experiments establish the first link between corollary discharge and visual processing, delineate a brain circuit that is well suited for mediating visual stability, and provide a framework for studying corollary discharge in other sensory systems.     

Effects of sleep and arousal on the processing of visual information in the cat

Single units in the cat lateral geniculate nucleus and primary visual cortex show changes in both spontaneous and visually evoked firing as a function of the state of wakefulness. On arousal spontaneous firing is smoother and often reduced, whereas evoked responses are usually enhanced; the result is an increase in the signal-to-noise ratio. Single- and double-label 2-deoxyglucose autoradiographs show further that slow-wave sleep differentially depresses visually evoked activity in the deeper layers of the visual cortex.