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  • You might have heard that light is a kind of wave

    你可能聽過光具有波動性,

  • and that the color of an object

    而物體的顏色取決於

  • is related to the frequency of light waves it reflects.

    該物體反射出光線的頻率。

  • High-frequency light waves look violet,

    高頻率的光波看起來是紫色,

  • low-frequency light waves look red,

    低頻率的光波看起來是紅色,

  • and in-between frequencies look yellow,

    而且兩者中間的頻率看起來可能是黃色、

  • green,

    綠色、

  • orange,

    橘色

  • and so on.

    等顏色。

  • You might call this idea physical color

    你可以說這是物理性的顏色,

  • because it says that color is a physical property of light itself.

    因為它表示光的顏色源自於本身屬性。

  • It's not dependent on human perception.

    和人類解讀能力沒有關係。

  • And, while this isn't wrong,

    雖然這並非錯誤,

  • it isn't quite the whole story either.

    但是不能完全解釋人如何辨別顏色。

  • For instance, you might have seen this picture before.

    舉例而言,你可能看過這張圖。

  • As you can see, the region where the red and green lights overlap is yellow.

    如你所見,紅色和綠色光疊加看起來是黃色。

  • When you think about it, this is pretty weird.

    但如果你仔細思考,就會覺得怪怪的。

  • Because light is a wave, two different frequencies

    因為光具波動性,兩種不同頻率的光波

  • shouldn't interact with each other at all,

    不應該會有交互作用,

  • they should just co-exist

    它們應該像是合唱演出般

  • like singers singing in harmony.

    共同存在。

  • So, in this yellow looking region,

    所以,在你看起來是黃色的區域

  • two different kinds of light waves are present:

    有兩種光波存在:

  • one with a red frequency,

    一種是紅光光波

  • and one with a green frequency.

    另一種是綠光光波。

  • There is no yellow light present at all.

    但這裡並無黃光光波的存在

  • So, how come this region,

    那為什麼這個

  • where the red and green lights mix,

    紅色和綠色疊加的區域

  • looks yellow to us?

    看起來會是黃色呢?

  • To understand this, you have to understand a little bit about biology,

    要瞭解這個現象,必須先學學生物學——

  • in particular, about how humans see color.

    尤其是關於人如何看到顏色的部份。

  • Light perception happens in a paper-thin layer of cells,

    光由人類眼球底部

  • called the retina,

    薄薄一層

  • that covers the back of your eyeball.

    被稱為視網膜的細胞所接收。

  • In the retina, there are two different types of light-detecting cells:

    在視網膜上有兩種感光細胞

  • rods and cones.

    桿狀細胞和錐狀細胞,

  • The rods are used for seeing in low-light conditions,

    其中桿狀細胞在低亮度時 負責接收,

  • and there is only one kind of those.

    而且只有一種。

  • The cones, however, are a different story.

    而錐狀細胞就有所不同了!

  • There three kinds of cone cells that roughly correspond

    我們有三種錐狀細胞,

  • to the colors red,

    他們分別對應紅色、

  • green,

    綠色、

  • and blue.

    和藍色。

  • When you see a color,

    當你看到顏色時,

  • each cone sends its own distinct signal to your brain.

    不同的錐狀細胞會將不同的訊息送向腦部。

  • For example, suppose that yellow light,

    舉例而言,

  • that is real yellow light, with a yellow frequency,

    當有一道真正具有黃色頻率的光線

  • is shining on your eye.

    射入你眼睛時,

  • You don't have a cone specifically for detecting yellow,

    你並沒有專門負責接收黃光的錐狀細胞。

  • but yellow is kind of close to green

    但是因為黃色和綠色

  • and also kind of close to red,

    及紅色相近,

  • so both the red and green cones get activated,

    所以負責紅色和綠色的錐狀細胞會被活化,

  • and each sends a signal to your brain saying so.

    分別傳送訊息到你的腦部。

  • Of course, there is another way to activate

    當然,有另一種方式可以達到相同效果:

  • the red cones and the green cones simultaneously:

    紅色和綠色光同時抵達,

  • if both red light and green light are present at the same time.

    造成負責紅色和綠色的錐狀細胞同時被啓動。

  • The point is, your brain receives the same signal,

    這時候腦部會收到相同的訊號,

  • regardless of whether you see light that has the yellow frequency

    不論是接受一束黃光

  • or light that is a mixture of the green and red frequencies.

    或是由紅光和綠光所混成的光線都是一樣。

  • That's why, for light, red plus green equals yellow.

    所以對光線來說,紅色加綠色就成了黃色。

  • And, how come you can't detect colors when it's dark?

    那為何你無法在黑暗中辨別色彩呢?

  • Well, the rod cells in your retina take over

    這是因為在低亮度的狀況下

  • in low-light conditions.

    是由視網膜上的桿狀細胞接手感光。

  • You only have one kind of rod cell,

    但是你只有一種桿狀細胞,

  • and so there is one type of signal

    所以它只能送出一種訊號

  • that can get sent to your brain:

    告訴你的大腦

  • light or no light.

    是亮還是暗。

  • Having only one kind of light detector

    因為只有一種偵測器,

  • doesn't leave any room for seeing color.

    所以沒辦法偵測看到的顏色。

  • There are infinitely many different physical colors,

    物理顏色近乎無限多種,

  • but, because we only have three kinds of cones,

    而我們只有三種錐狀細胞,

  • the brain can be tricked into thinking it's seeing any color

    大腦則藉由運算

  • by carefully adding together the right combination

    紅、綠、藍

  • of just three colors:

    這訊號強弱相加的結果

  • red, green, and blue.

    讓我們看到不同色彩。

  • This property of human vision is really useful in the real world.

    人類視覺原理在真實世界中十分有用。

  • For example, TV manufacturing.

    例如:電視機的製造。

  • Instead of having to put infinitely many colors in your TV set

    與其要放進無限種顏色的光源

  • to simulate the real world,

    以模擬真實世界的色彩。

  • TV manufacturers only have to put three:

    電視製造商只需要用到三種光源:

  • red, green, and blue,

    紅、綠、藍。

  • which is lucky for them, really.

    這對他們來說真是太幸運了!

You might have heard that light is a kind of wave

你可能聽過光具有波動性,

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B1 中級 中文 TED-Ed 細胞 錐狀 顏色 紅色 綠色

【TED-Ed】我們如何看到顏色? How we see color - Colm Kelleher

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    VoiceTube   發佈於 2013 年 03 月 23 日
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