Vision

（视觉生物科学）

       In order for us to see an object it is necessary for a source (the sun, a lamp) to direct its rays onto it, which it then directs, suitably modified, onto the eyes. Such signals are then elaborated by the brain, which subsequently makes a decision, readjusting the image with a retroactive process (feedback). It may, for example, close the pupil if the light is excessive.(讲述眼球—事物对象—大脑神经皮质三者关系！初中物理老师讲相机原理，下面呼啦呼啦睡了一大片。。还有O(∩_∩)O哈哈~)

The human eye(人眼)
The radiation emitted or reflected from objects around us must be received by a well crafted instrument, our eyes, which in turn must select the correct quantity of light and bring images on the retina  into focus. Eyes are not simple receivers but also measure radiation according to wavelength by means of their sensitivity.(大家都很喜欢看的一个物体，你们懂得，初中生物老师将人体结构时，此章节略过...........所以那时候没听明白)

The retina （视网膜）

The retina is light sensitive substance which sits at the back of the eye. This zone is sprinkled with photoreceptors, except for the area in which the optic nerve is inserted, the so called blind spot.
The retina may be considered to be a pre-processor of our visual system

The blind spot（盲点）

The area of the retina in which the axons of the gangliar cells converge is called the blind spot and it is to be found about 15° from the fovea. This zone of the retina is unable to send the corresponding signals to the brain, as is shown in the following example.

Cover your left eye and focus on the number 3, place yourself very close to the screen and slowly move away. At a certain point the yellow disk will disappear from your vision. By repeating this exercise using different numbers you will note the various distances at which the disk disappears. The disappearance of the disk occurs when its image falls onto the blind spot.

            视网膜的后方称为眼底，在正对视神经起始处，有一呈白色的圆形隆起，称为视神经盘（又称视神经乳头）。此处是神经纤维进出的地方，没有感光细胞，不能感应到光线，故称为盲点。影像能够在盲点形成，但由于盲点没有感光细胞，所以不能产生神经脉冲，令脑部不能得到影像形成。（维基百科有精准图形解释！）

             In 1935, the psychologist Koffka asked, "Why do things appear the way they appear?"

The question is far less banal than it appears to be. Much evidence exists that that which we perceive does not only depend on physical reality, but also on the operation of our brain, and every theory of vision must take this into account.

In the figure we perceive a triangle which is whiter than the background even though there is absolutely no difference

（这张图学设计同学应该都见过吧，尤其是学视觉传达设计的同学）

Visual acuity is the eye's capacity to see the details of objects observed distinctly. In reality this depends on many factors, the differences in contrast between objects, the lighting, the tiredness of the eye and so on. Many people have a visual acuity lower than normal (indicated by twenty-twenty). These defects may also have influenced the work of some of the great artists. 大概主要讲视力的影响，现实生活当中一些较大的反差比事物都会影响到我们的视力，照明，视觉疲劳！这些问题就可能会影响到一些伟大艺术的的作品！

          （生活当中多去观察，why 高速指示牌和汽车车牌等为什么是蓝色、绿色、黄色..........O(-)O~！）

                                                                 同时做产品时多去思考图形设计过程中，多去什么背后的深成次科学因素！

                                                                                                具体详见设计师要懂得心理学

Ametropia（屈光）

When the image of an object that we see does not fall onto the retina, the result is an out of focus image. This can result in a series of visual problems such as myopia, hyperopia, astigmatism and presbyopia.

Ametropia can be resolved with the help of glasses, contact lenses or refractive surgery.

Ametropia and the arts(屈光和艺术)

Visual problems could certainly have influenced the work of great painters, even though we would not like to reduce artistic licence to a decision based on health problems.
Certainly when we take a look at an artwork by a young Turner completed in 1821 and compare it to one completed at a later stage in 1844, doubt arises whether his change in style was possibly in part a result of a difficulty in distinguishing details.

 https://en.wikipedia.org/wiki/J._M._W._Turner

                         这个骚年的画很浪漫，他是英国年轻艺术家Turne（透纳），这是他在1821年完成作品，与其中另一个作品在1844年后期完成，为什么两幅作品风格有如此较大差异，便产生疑问是！ 他在风格上的变化是否有可能存在部分细节辨别困难的结果导致的。推荐 导演: 迈克·李《透纳先生 Mr. Turner》 (2014奥斯卡摄影提)

                        https://en.wikipedia.org/wiki/Claude_Monet#/media/File:Water-Lilies-and-Japanese-Bridge-(1897-1899)-Monet.jpg   （大图）   

莫奈就不用讲了！学过绘画的同学都知道，他在1922年左右，遭受白严重内障，所以当时做了必要的手术。这部分解释了画在1899年和1922年的日本桥之间的差异变化。

https://en.wikipedia.org/wiki/Rembrandt

这是伦勃朗老爷子的绘画，画之间改变颜色和细节，都是在他青年与他完成前更高深的年龄。

http://zhouhuiyingdesign.lofter.com/post/1d1597cd_67aba0e

 这个是真正的人才埃尔·格列柯，这哥们描绘的人物画的特别加长。然而,利用光学技术的发现， 已经被一些学者认定为是散光的结果。关键是他每次准备工作时，都提出了正确的比例, 这就使我们认为这些数据实际上是一种文体的神秘指！

The vision of colour(视觉色彩)

Lncident light (入射光)

The colour of an object depends on the radiation that is directed onto it. In fact, if a magenta object (magenta is the colour obtained by combined red and blue) is hit by white radiation, which contains all the colours, it will reflect red and blue. But if the source that illuminates it does not contain blue, the object can not reflect it and will therefore assume a red appearance. In any case, it is always necessary to take into accoun constancy of colour

Backgrounds（背景）

Colour depends on the background on which it is presented, as we can see in this example.Taking into account the importance of backgrounds it is amazing to discover that, up until the 1800's, paintings were exhibited on red walls regardless of the frame. The Impressionists were the first to understand the importance of the frame and the background.（在这个例子中我们可以看出，颜色取决于其所在的背景,。直到1800年代,画红色的墙不管框架上展出，令人惊异的发现,他考虑背景的重要性,。印象派画家首先要理解框架和背景的重要性。）

Psychophysical measurements(心理测量)

In order to evaluate the behaviour of a light source it is not sufficient to analyse technical characteristics measurable with instruments. It is in fact very important to evaluate the effect that such a source has on human vision. This can be observed only by implementing psychophysical measurements, i.e. measurements which use human patients and take into consideration their answers to various visual stimuli and the light source considered.

It has recently become increasingly more apparent that the computer monitor is used as a generator of psychophysical stimuli

Optical illusions(光学错觉)

The complexity of our visual system leads to a series of strange problems that are not always easily explainable: let's take a look at some optical effects which often have interesting scientific implications.
To start with observe the diagram on the right: you should be able to identify two different forms.

Impossible shapes(不可能的图形)

Some illustrations are clearly impossible for our visual system.

A typical example is this triangle.

Reversible perspective（可逆的视角）

Reversible perspective refers to illustrations which can be interpreted by our brains in two different ways even if there is not change in the picture. On the left is Necker's cube: which is the back and the front?
In the centre, a seat on which we can sit or a roof under which to shelter?
Finally, does it go up or down?