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科学家是如何给太空照片上色的?

How scientists colorize photos of space

1: RGB
This is all the light in the universe that we can see.
这就是我们能看到的宇宙中全部的光
It’s just a fraction of what’s out there.
但这些光只是光谱的一部分
Most frequencies of light are actually invisible to us.
实际上大部分光是我们看不到的
The light we can see appears red at its lowest frequencies and violet at its highest.
人眼能看见的最低频的光是红光 最高频的光是紫光
This is called the “visible spectrum”
这就是“可见光谱”
and we see it because cells in our eyes called
而我们能看见是因为眼中的
“cones” interpret light reflecting off of objects.
“视锥细胞”感知到了物体反射的光
We have three different types of cones that are sensitive to long, medium,
我们有三种不同类型的“视锥细胞”
and short wavelengths of light.
可以感知长波 中波和短波的光
Which roughly correspond to red, green, and blue on the visible spectrum.
大致上与可见光谱上的红 绿 蓝三色对应
These are the primary colors of light.
这就是光的三原色
Every other color is some combination of these three.
其他颜色由这三种颜色组合而成
And that combination is the guiding princ iple in colorizing black and white images.
三原色的组合是给黑白图像上色的指南
2:上色
This portrait was taken in 1911.
这张照片拍摄于1911年
I know. You came here for space photos.
我知道你是为了太空照片来的
We’re getting there, I promise.
我们马上讲到 我打包票
It’s one of the first examples of color photography,
这是早期彩色摄影的一个例子
and it’s actually three black-and-white photos composited together.
这实际上是三张黑白照片合成的
Russian chemist Sergei Prokudin-Gorskii took three identical shots of this man, Alim Khan,
俄罗斯化学家谢尔盖·普罗库丁-戈尔斯基为Alim Khan拍了三张一样的照片
using filters for specific colors of light.
他用滤片对特定颜色的光进行筛选
One allowed red light to pass through, one allowed green,
一张只留红光 一张只留绿光
and one allowed blue.
一张只留蓝光
You can really see how effective this filter system is
你可以通过比较红光和蓝光下曝光的照片
when you compare the red and blue exposures.
看到这个滤片的成效
Look how bright Khan’s blue robe is
Khan的蓝色长袍部分
in the photo on the right,
在右边的照片里更加亮
meaning all of that color light passed through the filter.
意味着更多的蓝光穿过了滤片
Dyeing and combining the three negatives gives you this.
把三张负片染色后叠加得到这个效果
Alright,you get the idea.
现在你已经明白了原理
So let’s take it into space.
我们把它应用到太空中
3:宽频颜色
The Hubble Space Telescope has been orbiting Earth since1990,
哈勃望远镜从1990年起环绕地球
expanding human vision into deep space
把人类的视野延伸到了外太空
and giving us images like this one.
并给我们传回这样的图像
The thing is, every Hubble image you see started out black-and-white.
事实上 你看到的所有哈勃图像一开始都是黑白的
That’s because Hubble’s main function is
这是因为哈勃望远镜的主要功能是
to measure the brightness of light reflecting off objects in space,
测量在太空中物体反射光的亮度
which is clearest in black-and-white.
这种反差在黑白模式下最明显
The color is added later,
颜色是后来加的
just like the portrait of Alim Khan/
就像Alim Khan的照片一样
Except today, scientists use computer programs like Photoshop.
不同的是 今天的科学家们用Photoshop这类软件给照片上色
Let’s use this photo of Saturn as an example.
我们以土星的照片为例
Filters separate light into long, medium, and short wavelengths.
滤波器把光分成长波 中波和短波
This is called “broadband filtering”
这叫“宽带过滤”
since it targets general ranges of light.
因为这利用了光的大致分布区间
Each of the three black-and-white images are then assigned a color
这三张黑白照片中的每一张都会
based on their position on the visible spectrum.
根据它在可见光谱上的位置染上一种颜色
The combined result is a “true color “image,
合并得到物体的“真实颜色”
or what the object would look like
抑或你的眼睛和
if your eyes were as powerful as a telescope like Hubble.
哈勃望远镜一样强大时所看到的样子
Okay now one with Jupiter.
现在以木星为例
See how combining the red and green brings in yellow?
看到红色和绿色组合而成的黄色了吗?
And then adding blue brings cyan and magenta to fully represent visible spectrum.
再加上蓝色得到青色和洋红色就可以得到可见光谱上的所有颜色
Watch this animation two more times and I think you’ll see it.
再看两遍动画 我觉得你会理解的
Great,now let’s add another level of complexity.
现在加点儿难度
Seeing an object as it would appear to our eyes
还原物体在眼中呈现的颜色
isn’t the only way to use color.
不是使用颜色的唯一方式
Scientists also use it to map out how different gases interact
科学家还用颜色勾勒出了宇宙中
in the universe to form galaxies and nebulae.
形成星系和星云的不同气体的反应
Hubble can record very narrow bands
哈勃望远镜能记录到
of light coming from individual elements, like oxygen
像氧和碳这种单个元素发出的狭窄光带
and carbon, and use color to track their presence in an image.
然后用颜色追踪它们在图像中的身影
This is called “narrowband filtering”.
这就是“窄带滤波”
The most common application of narrowband filtering isolates light from hydrogen, sulfer and oxygen,
窄带滤波最广泛的应用是把光从氢 硫和氧元素中分离开来
three key building blocks of stars.
它们是构成星体的三大基本元素
Hubble’s most famous example of this is called the Pillars of Creation,
哈勃望远镜拍摄到的最著名的图像是创生之柱
which captured huge towers of gas and dust forming new star systems.
其捕捉到了巨塔状气体和尘埃 正形成新的恒星系统
But this isn’t a ” true color “image,
但这不是图像的“真实颜色”
like the one of Saturn from before.
和之前土星的照片一样
It’s more of a colorized map.
这是人工上色的图像
Hydrogen and sulfur are both seen naturally in red light,
自然状态下的氢元素和硫元素是红色的
and oxygen is more blue.
氧元素偏蓝色
Coloring these gases as we’d actually see them would produce red, red and cyan,
依据人眼感觉将其染为红色 红色和青色
and the Pillars of Creation would look more like this.
创生之柱大概是这个样子
Not as useful for visual analysis.
这在视觉分析中用处不大
In order to get a full color image
为了得到全彩图像
and visually separate the sulfur from the hydrogen,
也为了让人眼分辨出硫元素和氢元素
scientists assign the elements to red,
科学家把三种元素
green and blue according to their place in the “chromatic order”.
依照它们的“色阶顺序” 定为红 绿 蓝
Basically that means that since oxygen has the highest frequency of the three,
总的来说 氧元素发出的光频率最高
it’s assigned blue.
它被指定为蓝色
And since hydrogen is red but a higher frequency than sulfur
氢元素是红色 但其光频率比硫元素更高
it gets green.
因而被指定为绿色
The result is a full color image mapping out the process
最终得到一张
by which our own solar system might have formed.
可能是我们太阳系形成过程的全彩图像
5:呈现色
The Hubble Space Telescope can record light
哈勃望远镜还可以记录到
outside of the visible spectrum too –
除了可见光谱外的
in the ultraviolet and near-infrared bands.
在紫外光谱和近红外光谱上的光
An infrared image of the Pillars of Creation,
用红外成像得到的创生之柱图像
for example, looks very different.
与之前得到的图像不同
The longer wavelengths penetrate the clouds
长波穿过了气体和尘埃形成的云层
of dust and gas that block out visible light frequencies,
使可视光不被云层所遮挡
revealing clusters of stars within it and beyond.
从而展现出内外星团的面貌
These images showing invisible light are colored the same way:
这些图像中的不可见光上色也是一样的:
multiple filtered exposures are assigned a color based on their place in chromatic order.
经过滤曝光的图像依色阶顺序被上色
Lowest frequencies get red, middle get green,highest get blue.
频率最低的涂红色 中间的涂绿色 最高的涂蓝色
Which could beg the question: are the colors real?
这里有一个问题:这种涂色准确吗?
Yes and no.
准确也不准确
The color represents real data.
这些颜色代表了真实的数据
And it’s used to visualize the chemical makeup of an object or an area in space
也被用来使太空中物体或区域的化学构成形象化
helping scientists see how gases interact thousands of lightyears away
帮助科学家理解几千光年外的气体作用方式
giving us critical information about how stars and galaxies form over time.
为我们了解星体和星系的形成过程提供重要信息
So even if it isn’t technically how our eyes would perceive these objects
即使我们眼睛看到的物体不是准确的样子
it‘s not made up, either.
这些图像也不是凭空臆造的
The color creates beautiful images,
颜色创造了美丽的图景
but more importantly-it shows us the invisible parts of our universe.
更重要的是 向我们展现了宇宙中不可见的一部分

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视频概述

美丽的太空照片实际上真的那么绚丽多彩吗?科学家是如何知道光年外的太空是什么颜色的?这个视频会告诉你答案.

听录译者

收集自网络

翻译译者

hilme

审核员

审核员 V

视频来源

https://www.youtube.com/watch?v=WSG0MnmUsEY

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