B1 中級 17 分類 收藏
開始影片後,點擊或框選字幕可以立即查詢單字
字庫載入中…
回報字幕錯誤
If you put a colorful image into photoshop or instagram and blur it, you’ll see a weird,
dark boundary between adjacent bright colors.
Yuk!
In the real world, out of focus colors blend smoothly, going from red to yellow to green
– not red to brown to green!
This color blending problem isn’t limited to digital photo blurring, either – pretty
much any time a computer blurs an image or tries to use transparent edges, you’ll see
the same hideous sludge.
There’s a very simple explanation for this ugliness – and a simple way to fix it.
It all starts with how we perceive brightness.
Human vision, like our hearing, works on a relative, roughly logarithmic scale: this
means that flipping from one light to two changes the percieved brightness a TON more
than going from a hundred and one to a hundred and two, despite adding the same physical
amount of light.
Our eyes and brains are simply better at detecting small differences in the absolute brightness
of dark scenes, and bad at detecting the same differences in bright scenes.
Computers and digital image sensors, on the other hand, detect brightness purely based
on the number of photons hitting a photodetector – so additional photons register the same
increase in brightness regardless of the surrounding scene.
When a digital image is stored, the computer records a brightness value for each colors
– red, green and blue – at each point of the image.
Typically, zero represents zero brightness and one represents 100 percent brightness.
So 0.5 is half as bright as 1, right?
NOPE.
This color might LOOK like it’s halfway between black and white, but that’s because
of our logarithmic vision – in terms of absolute physical brightness, it’s only
one fifth as many photons as white.
Even more crazy, an image value of 0.25 has just one twentieth the photons of white!
Digital imaging has a good reason for being designed in this darker-than-the-numbers-suggest
way: remember, human vision is better at detecting small differences in the brightness of dark
scenes, which software engineers took advantage of as a way of saving disk space in the early
days of digital imaging.
The trick is simple: when a digital camera captures an image, instead of storing the
brightness values it gives, store their square roots – this samples the gradations of dark
colors with more data points and bright colors with fewer data points, roughly imitating
the characteristics of human vision.
When you need to display the image on a monitor, just square the brightness back to present
the colors properly.
This is all well and good – until you decide to modify the image file.
Blurring, for example, is achieved by replacing each pixel with an average of the colors of
nearby pixels.
Simple enough.
But depending on whether you take the average before or after the square-rooting gives different
results!!
And unfortunately, the vast majority of computer software does this incorrectly.
Like, if you want to blur a red and green boundary, you’d expect the middle to be
half red and half green.
And most computers attempt that by lazily averaging the brightness values of the image
FILE, forgetting that the actual brightness values were square-rooted by the camera for
better data storage!
So the average ends up being too dark, precisely because an average of two square roots is
always less than the square root of an average.
To correctly blend the red and green and avoid the ugly dark sludge, the computer SHOULD
have first squared each of the brightnesses to undo the camera’s square rooting, then
averaged them, and then squared-rooted it back – look how much nicer it is!!
Unfortunately, the vast majority of software, ranging from iOS to instagram to the standard
settings in Adobe Photoshop, takes the lazy, ugly, and wrong approach to image brightness.
And while there are advanced settings in photoshop and other professional graphics software that
let you use the mathematically and physically correct blending, shouldn’t beauty just
be
the default?
提示:點選文章或是影片下面的字幕單字,可以直接快速翻譯喔!

載入中…

Computer Color is Broken

17 分類 收藏
林宜悉 發佈於 2020 年 3 月 28 日
看更多推薦影片
  1. 1. 單字查詢

    在字幕上選取單字即可即時查詢單字喔!

  2. 2. 單句重複播放

    可重複聽取一句單句,加強聽力!

  3. 3. 使用快速鍵

    使用影片快速鍵,讓學習更有效率!

  4. 4. 關閉語言字幕

    進階版練習可關閉字幕純聽英文哦!

  5. 5. 內嵌播放器

    可以將英文字幕學習播放器內嵌到部落格等地方喔

  6. 6. 展開播放器

    可隱藏右方全文及字典欄位,觀看影片更舒適!

  1. 英文聽力測驗

    挑戰字幕英文聽力測驗!

  1. 點擊展開筆記本讓你看的更舒服

  1. UrbanDictionary 俚語字典整合查詢。一般字典查詢不到你滿意的解譯,不妨使用「俚語字典」,或許會讓你有滿意的答案喔