Comparison of an automated pattern analysis machine vision time-lapse system with traditional endpoint measurements in the analysis of cell growth and cytotoxicity

Machine vision is an application of computer vision. It both collects visual information and interprets the images. Although the machine obviously does not 'see' in the same sense that humans do, it is possible to acquire visual information and to create programmes to identify relevant image features in an effective and consistent manner. Machine vision is widely applied in industrial automation, but here we describe how we have used it to monitor and interpret data from cell cultures. The machine vision system used (Cell-IQ) consisted of an inbuilt atmosphere-controlled incubator, where cell culture plates were placed during the test. Artificial intelligence (AI) software, which uses machine vision technology, took care of the follow-up analysis of cellular morphological changes. Basic endpoint and staining methods to evaluate the condition of the cells, were conducted in parallel to the machine vision analysis. The results showed that the automated system for pattern analysis of morphological changes yielded comparable results to those obtained by conventional methods. The inbuilt software analysis offers a promising way of evaluating cell growth and various cell phases. The continuous follow-up and label-free analysis, as well as the possibility of measuring multiple parameters simultaneously from the same cell population, were major advantages of this system, as compared to conventional endpoint measurement methodology.     

Bayesian models of object perception

The human visual system is the most complex pattern recognition device known. In ways that are yet to be fully understood, the visual cortex arrives at a simple and unambiguous interpretation of data from the retinal image that is useful for the decisions and actions of everyday life. Recent advances in Bayesian models of computer vision and in the measurement and modeling of natural image statistics are providing the tools to test and constrain theories of human object perception. In turn, these theories are having an impact on the interpretation of cortical function.     

线画图形质地辨认的一个神经网络模型

本文提出了一个能辨认线画质地的神经网络模型,并在IBM-PC机上对它进行了成功的模拟.该模型可与真实的视觉系统建立起很好的对应关系,因此可以认为它是对视觉系统质地辨认过程的一个机器再现.另外,本文推广了原广义Gabor函数模型,得到了一个适合于描写网络层次视觉功能的单细胞感受野的数学描述.     

Interaction of ON and OFF pathways for visual contrast measurement

We propose a novel model of visual contrast measurement based on segregated On and Off pathways. Two driving forces have shaped our investigation: (1) establishing a mechanism selective for sharp local transitions in the luminance distribution; (2) generating a robust scheme of oriented contrast detection. Our starting point was the architecture of early stages in the mammalian visual system. We show that the circuit behaves as a soft AND-gate and analyze the scale-space selectivity properties of the model in detail. The theoretical analysis is supplemented by computer simulations in which we selectively investigate key functionalities of the proposed contrast detection scheme. We demonstrate that the model is capable of successfully processing synthetic as well as natural images, thus illustrating the potential of the method for computer vision applications. Received: 5 June 1998 / Accepted in revised form: 12 May 1999     

The architecture of visual cortex and inferential processes in vision

This paper is organised approximately into two halves. In the first half, I review evidence about the structure of the visual system, and I use that evidence to frame what I think are widely held but often implicit ideas about how it works, namely that vision is principally analysis of retinal input. These ideas have been strongly influenced by engineering approaches; form a default view of the visual system that suffuses all the language used to describe it (at least in visual neuroscience); and are to some extent supported by the structural evidence. In the second half, I explore some inconvenient facts from neuroanatomy and neurophysiology which are quite uncomfortable for the traditional view. I then set out a contrary view of how structure and function are linked in the visual system, which is a neurobiological variety of the quite developed view in psychophysics that vision is better understood as knowledge-rich inference. Finally, I explore some of the ramifications of this view for neurophysiological understanding of how the visual system might operate during normal vision.     

计算机视觉技术在植物学中的应用

介绍计算机视觉技术的定义、组成系统和发展状况,总结其在植物学中的应用,指出目前存在的问题以及需要重点解决的关键技术,为今后的深入研究提出了一些建议和方向。     

计算机视觉技术在昆虫识别中的应用进展

介绍计算机视觉技术的定义,组成系统和发展状况,总结其在昆虫识别中的应用,指出目前存在的问题以及需要重点解决的关键技术．为今后的深入研究提出了一些建议和方向。     

Visual textures, machine vision and animal camouflage

The psychophysics of visual texture perception and texture discrimination have been investigated extensively during the past 30 years. Humans have been the main study subjects, but some research on texture perception has involved other species, and there is good reason to think that the most general results from humans apply to other vertebrates as well. Psychophysicists have suggested that some of their findings on human vision reflect adaptive 'tricks' for countering prey camouflage, but this possibility has not been widely communicated to evolutionary biologists. We review the psychophysicists' main conclusions on texture discrimination, and list additional questions that their results raise when animal coats are considered as visual textures. We also suggest ways in which advances in computer vision can be combined with psychophysics to provide new perspectives on the function of animal coat patterns.     

视觉假体的研究进展与面临的挑战

人工视觉假体是当今国际上对视网膜色素变性和老年性黄斑病变患者进行视觉修复的研究热点,该人工装置采集外界图像信息,并进行编码处理,通过微电流刺激器将刺激微电流信号加载到微电极阵列,对视觉神经系统进行作用,从而在视觉中枢产生光幻视,实现视觉功能修复。根据目前的国际研究现状,视觉假体可以对视觉通路的任意位置进行电刺激,以期产生视光感。按照植入位置的不同,视觉假体基本上可以分为视皮层假体、视网膜上假体、视网膜下假体和视神经假体。本文着重介绍了中国的C-Sight小组在视神经假体方面的工作进展和面临的挑战。     

Vision in elasmobranchs and their relatives: 21st century advances

This review identifies a number of exciting new developments in the understanding of vision in cartilaginous fishes that have been made since the turn of the century. These include the results of studies on various aspects of the visual system including eye size, visual fields, eye design and the optical system, retinal topography and spatial resolving power, visual pigments, spectral sensitivity and the potential for colour vision. A number of these studies have covered a broad range of species, thereby providing valuable information on how the visual systems of these fishes are adapted to different environmental conditions. For example, oceanic and deep-sea sharks have the largest eyes amongst elasmobranchs and presumably rely more heavily on vision than coastal and benthic species, while interspecific variation in the ratio of rod and cone photoreceptors, the topographic distribution of the photoreceptors and retinal ganglion cells in the retina and the spatial resolving power of the eye all appear to be closely related to differences in habitat and lifestyle. Multiple, spectrally distinct cone photoreceptor visual pigments have been found in some batoid species, raising the possibility that at least some elasmobranchs are capable of seeing colour, and there is some evidence that multiple cone visual pigments may also be present in holocephalans. In contrast, sharks appear to have only one cone visual pigment. There is evidence that ontogenetic changes in the visual system, such as changes in the spectral transmission properties of the lens, lens shape, focal ratio, visual pigments and spatial resolving power, allow elasmobranchs to adapt to environmental changes imposed by habitat shifts and niche expansion. There are, however, many aspects of vision in these fishes that are not well understood, particularly in the holocephalans. Therefore, this review also serves to highlight and stimulate new research in areas that still require significant attention.     

Visual Function Assessment in Simulated Real-Life Situations in HIV-Infected Subjects

Visual function abnormalities are common in people living with HIV disease (PLWH) without retinitis, even after improvement in immune status. Abnormalities such as reduced contrast sensitivity, altered color vision, peripheral visual field loss, and electrophysiological changes are related to a combination of retinal dysfunctions, involving inner and outer retinal structures. The standard protocol for testing vision performance in clinical practice is the Early Treatment Diabetic Retinopathy Study (ETDRS) chart. However, this method poorly correlates with activities of daily living that require patients to assess visual stimuli in multiple light/contrast conditions, and with limited time. We utilized a novel interactive computer program (Central Vision Analyzer) to analyze vision performance in PLWH under a variety of light/contrast conditions that simulate stressful and real-world environments. The program tests vision in a time-dependent way that we believe better correlates with daily living activities than the non-timed ETDRS chart. We also aimed to correlate visual scores with retinal neuro-fiber layer thickness on optical coherence tomography. Here we show that visual acuity is more affected in PLWH in comparison to HIV-seronegative controls in varying contrast and luminance, especially if the nadir CD4+ T-cell count was lower than 100 cells/mm³. Visual impairment reflects the loss of retinal nerve fiber layer thickness especially of the temporal-inferior sector. In PLWH the ETDRS chart test led to better visual acuity compared to the Central Vision Analyzer equivalent test, likely because patients had indefinite time to guess the letters. This study confirms and strengthens the finding that visual function is affected in PLWH even in absence of retinitis, since we found that the HIV serostatus is the best predictor of visual loss. The Central Vision Analyzer may be useful in the diagnosis of subclinical HIV-associated visual loss in multiple light/contrast conditions, and may offer better understanding of this entity called “neuroretinal disorder”.     

Neural circuitry: seeing the parts that make the picture

What are the neural correlates of vision? A recent study on Drosophila has described the incredible neuronal diversity in the fly visual system, and traced the circuits that underlie color vision.     

Environmental factors which may have led to the appearance of colour vision

It is hypothesized that colour vision and opponent processing of colour signals in the visual system evolved as a means of overcoming the extremely unfavourable lighting conditions in the natural environment of early vertebrates. The significant flicker of illumination inherent in the shallow-water environment complicated the visual process in the achromatic case, in particular preventing early detection of enemies. The presence of two spectral classes of photoreceptors and opponent interaction of their signals at a subsequent retinal level allowed elimination of the flicker from the retinal image. This new visual function provided certain advantages concerning reaction times and favoured survival. This assumption explains why the building blocks for colour vision arose so early, i.e. just after the active predatory lifestyle was mastered. The principal functions of colour vision inherent in extant animals required a more complex neural machinery for colour processing and evolved later as the result of a change in visual function favouring colour vision.     

A model of visual recognition and categorization.

To recognize a previously seen object, the visual system must overcome the variability in the object''s appearance caused by factors such as illumination and pose. Developments in computer vision suggest that it may be possible to counter the influence of these factors, by learning to interpolate between stored views of the target object, taken under representative combinations of viewing conditions. Daily life situations, however, typically require categorization, rather than recognition, of objects. Due to the open-ended character of both natural and artificial categories, categorization cannot rely on interpolation between stored examples. Nonetheless, knowledge of several representative members, or prototypes, of each of the categories of interest can still provide the necessary computational substrate for the categorization of new instances. The resulting representational scheme based on similarities to prototypes appears to be computationally viable, and is readily mapped onto the mechanisms of biological vision revealed by recent psychophysical and physiological studies.     

Vision as a third sensory modality to elicit attack behavior in a nocturnal spider

Cupiennius salei (Ctenidae) has been extensively studied for many years and is probably the only spider that presently can be considered a model organism for neuro-ethology. The night-active spiders have been shown to predominantly rely on their excellent mechano-sensory systems for courtship and prey capture, whereas vision was assumed to play a minor role, if any, in these behavioral contexts. Using slowly moving discs presented on a computer screen it could be shown for the first time that visual stimuli alone can elicit attack behavior (abrupt approaching reactions) in these spiders as well. These observations suggest that visual information could be used by the spiders to elicit and guide predatory behavior. Attack behavior in Cupiennius salei can thus be triggered independently by three sensory modalities—substrate vibrations, airflow stimuli, and visual cues—and offers an interesting model system to study the interactions of multimodal sensory channels in complex behavior.     

The visual system of zebrafish and its use to model human ocular diseases

Free swimming zebrafish larvae depend mainly on their sense of vision to evade predation and to catch prey. Hence, there is strong selective pressure on the fast maturation of visual function and indeed the visual system already supports a number of visually driven behaviors in the newly hatched larvae.The ability to exploit the genetic and embryonic accessibility of the zebrafish in combination with a behavioral assessment of visual system function has made the zebrafish a popular model to study vision and its diseases.Here, we review the anatomy, physiology, and development of the zebrafish eye as the basis to relate the contributions of the zebrafish to our understanding of human ocular diseases.     

人工视觉辅助系统：现状与展望

通过视觉获取图像信息是人类学习和生活的重要功能,失明则会显著降低其生活质量.因视网膜色素变性、青光眼和黄斑变性等疾病而造成后天失明者,以及由意外事故、战争等造成眼部创伤者,有可能通过人工视觉辅助系统的帮助恢复部分视觉,或者完成复杂的生活任务.一些盲症患者视觉通路的神经传导剩余部分依然有功能,因此可以借助电极阵列刺激视神经向大脑传递视觉信息,也可在大脑视觉皮层贴敷电极阵列的方法输入视觉信息.此外,还能借助体外装置,如通过人工智能将视觉转换成语音指令、触觉阵列编码等,帮助盲症患者获得环境信息.本文综述各类人工视觉辅助系统的现状,展望其发展趋势,并提出了新的植入器件与随身体外装置的新设想.     

计算机视觉在植物显微结构观测中的应用

植物显微结构计算机视觉技术的研究已得到人们的重视,本文综述了计算机视觉在植物显微结构中几个重要方面的研究进展,包括计算机视觉的形成和发展,计算机视觉在植物显微结构中的应用和目前植物显微结构计算机视觉系统的组成和原理。