Unusual retinal cells in the dolphin eye

By comparison to the cellular constituents of the retinas of certain other diving mammals, the elements of the dolphin retina include an unusually large number of specialized cells. Both cone and rod receptors may be identified. An unusual amacrine cell may be seen which produces a process that spans the cells between the inner plexiform and outer plexiform layers. Most unusual is a layer of giant ganglion cells which appears to serve most of the central retina. The giant ganglion cells support giant dendrites and optic nerve fibers which range up to 8 micrometers in diameter.     

Local retinal regions control local eye growth and myopia

In chicks, visual deprivation leads to myopia and enlargement of the vitreous chamber of the eye. When chicks were raised with white translucent occluders over their eyes so that either the nasal half, the temporal half, or all of the retina was visually deprived, the resulting myopia (median = -15 diopters) was limited to the deprived part of the retina, regardless of which half of the retina was visually deprived; the nondeprived part remained nearly emmetropic. Correspondingly, the vitreous chamber was elongated only in the region of the visual deprivation, resulting in eyes with different asymmetric shapes depending on which retinal region was deprived. These results argue for a local regulation of ocular growth that is dependent on vision and suggest a hypothesis to explain the epidemiological association of myopia in humans with large amounts of reading. Because most nonfoveal retinal neurons have large receptive fields, they cannot resolve the individual letters on the printed page; this may lead to their activity being less during reading than during most other forms of visual stimulation. Thus, the impoverished stimulus situation of reading may lead to myopia, as do other types of visual form deprivation.     

Optical image quality and the cone mosaic

Contrary to the orthodox view that optical image quality should "match" the photoreceptor grain, anatomical data from the eyes of various animals suggest that the image quality is significantly superior to the potential resolution of the cone mosaic in most retinal regions. A new theory is presented to explain the existence of this relation and to better appreciate eye design. It predicts that photoreceptors are potentially visible through the natural optics.     

Aftereffect of seen motion with a stabilized retinal image

Prolonged inspection of uniformly moving contours affects differentially the luminance threshold for the detection of test contours as a function of the direction of motion of the test contours. This finding supports a new explanation of the well-known aftereffect.     

Gating of retinal transmission by afferent eye position and movement signals

Vision in most vertebrates is an active process that requires the brain to combine retinal signals with information about eye movement. Eye movement information may feed forward from the motor control areas of the brain or feed back from the extrinsic eye muscles. Feedback signals elicited by passive eye movement selectively gate retinal outflow at the first relay, the dorsal lateral geniculate nucleus. The gating predominantly facilitates retinogeniculate transmission immediately after eye movement and inhibits transmission when a new steady-state eye position is achieved. These two gating effects are distributed in a complementary fashion across the dorsal lateral geniculate nucleus such that the spatiotemporal activity profile could contribute to object detection and localization.     

A bivariate model for retinal image identification in lambs

In this paper we introduce the one-inflated bivariate Beta distribution as a new approach to analyze matching scores related to retinal image identification in lambs. These kind of data sets present many values equal to one, the perfect matching, and this justifies the introduction of one-inflation patterns. In addition, matching scores are correlated according to several bivariate patterns: left and right eye, 3 and 12 months of age, etc. Some examples of applications are given.     

Limulus lateral eye: properties of receptor units in the unexcised eye

Single receptor units in the compound eye of the horseshoe crab were illuminated, and their impulse discharges were recorded without removing the eye from the animal. The receptors were spontaneously active in darkness and responded without saturation over a light intensity range of 10(10) to 1. When the eye was excised, the receptors did not discharge in darkness and had an intensity range of 10(5) to 1, as is usually found. Experiments show that these and other differences result from cutting off the blood supply to the eye when it is excised. In addition, the range and shape of the intensity characteristic suggest that more than one receptor mechanism encodes light intensity in this eye.     

利用图像处理技术进行苹果外观质量检测

为提高检测效率和精度,实现苹果外观质量自动检验,采用数码相机获取苹果个体俯视和侧视数字影像,选取似圆度、体积和RGB颜色模式中R、G、B分量的灰度直方图作为苹果质量评价指标。通过二值化后的苹果俯视图和侧视图计算苹果似圆度和体积,根据待测苹果数字图像统计得到的其R、G、B各颜色分量灰度直方图与标准苹果相应指标比较,实现根据苹果外形与色泽的自动、快速外观质量检测。完整检测1个苹果的用时短于0.9s,满足实时检测的时间要求。这项技术可以用于苹果包装流水线作业,也可用于类似的农产品外观质量检测。     

小波自适应数字图像水印算法

将空域算法和频域算法有机结合，利用小波变换理论，给出了一种新的小波自适应数字图像水印算法。数值实验结果表明。嵌入水印后的图像与原始图像在视觉上无区别，该方法具有很好的不可觉察性。采用Jpeg水印信息和检测的水印信息之间的相关系数验证算法的鲁棒性，随着图像品质数的下降，相关系数略有下降，但幅度不大．表明算法具有较强的鲁棒性。     

牛肉图像直方图增强算法的改进

在传统直方图均衡的基础上，提出一种增强牛肉图像直方图的改进算法。先用一个函数来缩小最大的灰度频数与最小灰度频数之间的差距以使其更好保留细节，然后对有效的灰度级进行等间距处理以使图像在整个显示范围内显示。理论和实践证明本算法可以更好地保留细节，脂肪边界清楚，同时可使直方图更为平滑。     

Sevenless: a cell-specific homeotic mutation of the Drosophila eye

Each ommatidium in the compound eye of the Drosophila mutant sevenless lacks photoreceptor number seven (R7) from the normal ommatidial complement of eight photoreceptors. A comparison of mutant and normal development reveals that this deficit is caused by the cell-specific transformation of the cell normally fated to produce R7 into a lens-secreting accessory cell, a cone cell.