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眼睛的分辨率是多少? – 译学馆
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眼睛的分辨率是多少?

What Is The Resolution Of The Eye?

嘿 这里是Vsauce 我是Michael
Hey, Vsauce, Michael here,
我在位于美国首都华盛顿的白宫
I’m at the White House in America’s capital, Washington D.C.
美国每年拍摄很多故事片——我们有好莱坞
America makes a lot of feature films every year – Hollywood.
但它并不是产量最多的 尼日利亚的更多
But they don’t make the mostfeature films every year, Nigeria makes more.
而每年电影产量最多的国家是
But the country that makes the most films every single year is
印度 每两年
India. Every two years, the country of India
印度拍电影所用的胶卷连起来的话
fills up enough film with unique feature films
长得可以从孟买 连到我住的城市
that stretch all the way from this city, Mumbai,
伦敦
to where I live, in London.
这毫无疑问是好莱坞两年产量的两倍
That’s double what Hollywood produces in two years.
电影如此之多
That is a lot of movies,
但现实生活也是一部电影吗?
but is real-life a movie?
我曾讨论过眼睛的帧率
I’ve discussed the frame rate of the human eye before,
但是 与照相机或者屏幕相比
but how does the resolution of the human eye
眼睛的分辨率到底怎样呢?
compare to a camera or screen?
录像带 光碟 DVD 蓝光 还有IMAX
VHS, LaserDisc, DVD, Blu-ray, IMAX.
这些数字代表像素大小
Numbers like these are pixel dimensions.
它们相乘所得的结果就是
When multiplied, they tell us the total number
构成一张图片的像素总量
of picture elements an image is made up of,
此参数多用于描述数码相机的规格
a figure often used to describe digital cameras.
这个参数 听起来可能是越大越好
It might sound like more is better,
但要知道像1920×1080这样的数字
but to be sure numbers like 1920 by 1080
本质上并不表示分辨率 只是其中的一部分
are not resolutions per se. More pixels is only part of the equation.
分辨率是指分辨细节的能力
Resolution is about distinguishing fine details
而这种能力取决于很多其他因素
and that depends on a lot of other factors.
例如 曝光度 传感器尺寸
For instance, the amount of light, the size of the sensors,
这几百万像素实际编码的内容
what the millions of pixels are actually encoding and
以及对象的远近 我的意思是
how close the subject is. I mean,
近看萨尔瓦多·达利所画的
up close Salvador Dali’s painting of his wife
他妻子眺望地中海的画 可以被解析成一个个方块
looking at the Mediterranean can be resolved into boxes.
但拉远了看 喏 就是亚伯拉罕·林肯了
But from a far, well, it’s Abraham Lincoln.
真是岂有此理 当屏幕足够小
For crying out loud, on a small enough screen
距离足够远的时候
from far enough away,
无论屏幕标注的分辨率大小如何
low and high, so-called resolutions on screens,
我们看起来都没有区别
aren’t even resolved differently from one another by your eye.
相邻像素之间的差异也很重要
How different nearby pixels are from one another also matters.
这叫作空间分辨率
This is called spatial resolution.
比如说 如果我面前的镜头失焦
For instance, if I go out-of-focus
这个视频中的像素总量不会变
the number of pixels in the video frame stays the same
但是你不能解析出同样多的细节了
but you can’t resolve as much detail.
现在 有了这个思路
Now, with all this in mind
我们依然可以通过一个更好的问题把人的视觉
we can still compare human vision to a digital image,
和数字图像做一个比较 在其他条件理想的情况下
by asking a better question. Assuming everything else is optimal,
你需要多少像素
how many pixels would you need
去组成一张足够大的图像
to make an image on a screen large enough
来填充你的整个视野
to fill your entire field of view,
像现实生活一样 察觉不到像素点
look like real life without any detectable pixelation?
现在我们有了一些进展 在某种程度上
Now we are getting somewhere, Kind of.
这依然是一个比较粗糙的类比
The analogy is still crudy
因为整个帧是一次拍摄完成的
because a camera snaps an entire frame at once,
然而 我们的眼睛转来转去
whereas our eyes move around.
大脑会整合持续流入的信息
The brain amalgamates their constant stream of information
形成我们所谓的视觉
into what we call vision – sight.
实际上 眼球的匆匆一瞥所形成的影像
In fact, the image created by the eyeball alone during a single glance
实在难以接受 像电视坏了的影像
would hardly even be acceptable on a broken TV screen.
我们以为 眼睛形成的影像
We think our eyes create images
像这些Guy用相机帮我拍的照片一样
like this picture Guy took of me with a camera.
但是有一件事 和相机不同
But for one thing, unlike a camera,
你会看到一些杂物
you’ve got some stuff in the way.
比如 你总是会看到自己的鼻子
For instance, you are always looking at your own nose,
或者是眼镜 如果有的话
and maybe even glasses, if you have them.
幸运的是 我们的大脑会把它们处理掉
Luckily, our brains process those stimuli out
因为它们无关紧要 也不会改变
because they don’t matter and they don’t change.
但认为这些就是唯一的不同
But thinking those are the only difference
则是一个陷阱 字面意思上 或用拉丁语来说
is a pitfall, literally, latinly.
黄斑 来源于拉丁文 陷阱
The fovea gets its name from the Latin for ‘pitfall’.
它是视网膜上的一处凹陷
The fovea is the pit on your retina
负责接收视野中心两度左右区域的光线
that receives light from the central two degrees of your field of view,
大概是你伸直手臂时
about the area covered by both your thumbs
两个拇指的大小
when held at arms length away.
最理想的色彩视觉和最大视觉敏感度
Optimal colour vision and 20/20 acuity are
只在那一小部分区域里可能实现
only possible within that little area.
关于这些 XKCD作出了出色的解释
When it comes to these limitations XKCD has a brilliant illustration.
它还引出了其他问题 如盲点
It points out other problems, like blind spots,
字面上看是视觉的空白区域
literal blank spaces in our vision
该区域为视神经连接视网膜而形成
where the optic nerve meets up with the retina
接收不到视觉信息
and no visual information is received.
如果相机也会这样
If you bought a camera that did this,
你会把它退回厂家 你能通过闭上你的右眼
you would return it. You can find your own blind spot
来找到自己的视觉盲点
by closing your right eye,
用你的左眼盯着前方固定的某一点
fixating your left eye on a point in front of you,
伸出你左手拇指 放在视野的中心
extending your left thumb and then moving it
慢慢向左移动
left-of-center slightly slowly carefully
直到你看不到它 真神奇
until it’s not there anymore. Crazy!
当然 我们不会以这样可怕的方式去看世界
But of course, we don’t see the world horribly, like this,
因为你的眼睛一直在移动
because our eyes are constantly moving,
使整个影像都有黄斑一样清晰的解析度
dragging foveal resolution wherever we need it.
且大脑复杂的视觉系统 也会自动补全细节
And our brains’ complex visual system fills in details,
把来自两眼的影像合并 作出估算
merges images from both eyes and makes a lot of gueses.
我们真正看到的 是处理过的影像
What we actually see is a processed image,
不是指电脑产生的 而是大脑产生的
not computer-generated imagery, but well, meat-generated imagery.
霓虹色扩散错觉
The neon color spreading illusion
可以很好的阐释这两者的区别
is a great way to demonstrate this difference.
图像的中间其实没有蓝色光圈
There is no blue circle in this picture.
这里的白色和中间是一样的
The white here is the same as the white here.
镜头和屏幕都没有被欺骗
A camera isn’t fooled, a screen isn’t fooled,
只有你和稍纵即逝的知觉
only you and the fleeting gumbo of ingredients
被欺骗了
you call perception is fooled.
我们的视觉跟相机并不相同
Our vision is not analogous to a camera.
但我们重新提出的问题依然能解决
But our reformulated question can still be answered
因为人体在生理上
because human anatomy allows us to resolve,
能让我们分辨角距离
to differentiate certain angular distances.
著名的是 罗杰·恩·克拉克用0.59弧分
Famously, Roger N.Clark used a figure of 0.59 arcminutes
来计算人眼的分辨率
as the resolution of the human eye to calculate,
根据我们整个视野的大小
based on the size of our total field of view,
计算出到底多少不同的元素可以被容纳进视野中
how many of these distinct elements could fit inside of it.
结果正是我们想知道的精确结果的近似值
The result was an approximation of exactly what we want to know:
我们能分辨出多少个独立图像元素——像素
how many individual picture elements, pixels, our vision can appreciate.
他的答案是 五亿七千六百万个像素
His answer? 576 megapixels.
把这么多个像素放在
That many pixels, packed inside a screen large enough
和视野大小相同的屏幕中 不管距离远近
to fill your entire field of view, regardless of proximity,
都不会被常人察觉到有颗粒感
would be close enough to be undetectable by the average human eye.
但是我们要考虑到黄斑
But we should factor in the fovea,
因为克拉克的计算假设了最佳的视觉敏锐区
because Clark’s calculation assumes optimal acuity everywhere,
其中还包括了眼睛自由活动的情况
it allows the eye to move around.
但眼睛瞥一眼其实更像照片
But a single glance is more analogous to a camera snap,
结果是 只有大约七百万像素
and as it turns out, only about 7 megapixels,
在黄斑覆盖的视觉最佳的两度区域中
packed into the two degrees of optimal acuity the fovea covers
在眼球固定的情况下 就能察觉不到颗粒感
during a fixed stare, are needed to be rendered undetectable.
粗略估算一下
It’s been roughly estimated that
视野中剩下的区域 大约只需要
the rest of your field of view would only need about
一百万个像素就可以理解信息
1 megapixel more information.
现在听起来数字很小
Now that might sound low
但要知道 现在的很多科技
but keep in mind that there are plenty of modern technologies
所用的像素密度 我们都已经不能分辨
that already use pixel densities better than we can differentiate.
如班德·安斯乔诺莫所说
As Bad Astronomer deftly showed,
苹果的视网膜屏 所达到的像素密度
Apple’s Retina Displays truly do contain pixels at a density
在正常阅读距离 眼睛已不能分辨
average eyesight can’t differentiate from typical reading distances.
虽然屏幕大小和像素密度
But the fact that there are screen sizes and pixel densities
能够愚弄人们的眼睛
that can fool the human eye,
但并不意味着我们看东西的方式
is not a sign that we see
就会和数码相机的一样
in any kind of megapixelly way.
人类的视觉不是数字化的
Human vision just isn’t that digital.
我的意思是 的确
I mean, sure,
人类的视觉就像一个相机传感器
like a camera sensor we only have
有限且离散的细胞存在于我们的视网膜上
a finite and discrete number of cells in our retina.
但是大脑会调整最初感觉 变成我们的知觉
But the brain adjusts our initial sensations into a final perception,
这是一个极其复杂的感知过程
that is a wishy-washy top-down processed blob of experience.
而知觉不是由像素组成的
It’s not made of pixels, and furthermore unlike a camera,
更不像数码相机 能准确的储存在记忆中
it’s not saved in memory with veracity like a digital camera file.
目前还没有发现任何证据证明
Absolutely no evidence has ever been found for the existence of
一个真正的照相记忆的存在
a truly photographic memory.
更有趣的是
And what’s even cooler
我们不仅 不像数码相机一样
is that not only do we not visually resolve the real world
去解析这个世界
like a movie camera, we also don’t
在生活中 我们也不会像大部分电影剧本一样
narratively resolve conflict and drama in our lives
去理解冲突和故事
like most movie scripts.
我想表达的重点是
The point of all of this what I’m getting at,
一个想法 最初引导我发现这个问题的想法
is an idea. An idea that initially drew me to this question.
我们在生活这部电影里扮演各自的角色
We play roles in the movie of life,
但这不是一部普通的电影
but it’s a special kind of movie.
电影式的成败得失往往各自独立 就像像素
Cinematic victories and struggles are often discrete, resolved, like pixels,
有着难以置信的完美开篇和结局
with unbelievably perfect beginnings and endings,
然而现实世界全都是新年愿望
whereas the real world is all about year resolution.
我喜欢杰克在《电影狂人》中所讲的
I like how Jack Angstreich put it in’Cinemania’.
在电影里 角色做出一个决定后
In a movie, a character can make a decision
走过镜头 穿过大街
and then walk away from the camera across the street
电影谢幕 时间停滞在完美幸福的时刻
and have the credits roll, freezing life in a perfect happily ever after.
但是在现实生活 当你穿过街道
But in the real world, after you cross the street,
就该回家了 世界继续运转
you have to go home, the world goes on.
生活不是恒定在某个像素解析度
Life doesn’t appear in any particular pixel resolution
或者叙述解析度 生活是流动的
or narrative resolution. Things are continuous.
不管你来去匆匆
The world was running before you came around
世界如常运转
and it will continue running after you are gone.
你的生活只是一个情节 从开始一直到结束
Your life is a plot only in so far as it begins
直奔主题的发生着
and ends and occurs in medias res.
德莫瑞修为查理的《无终结》写的注释
Damerish opens illustration for Charles McGrath’s Endings
完美的诠释了这一切
Without Endings says it perfectly.
时间不止
In life, there rarely is
生命不息
the end. There is only
永无止境
the and, and as always.
感谢观看
Thanks for watching.

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视频概述

此视频是Vsauce的一个科普视频,讨论的是眼睛的分辨率。和相机、屏幕不一样,眼睛的成像更为复杂。

听录译者

收集自网络

翻译译者

chen~คิดถึง

审核员

审核员 D

视频来源

https://www.youtube.com/watch?v=4I5Q3UXkGd0

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