7 ms·

I dunno, but when I look at glowing blue signs and blue Christmas lights at night, they look significantly more fuzzy than other color lights.

usefulcat 5y ago
Also the blue LED on a PS3. Those always looked blurry to me. It’s especially obvious because of the adjacent green LED.
- farbissina 5y ago
  You are so right! I always assumed it was the LED's problem until I started reading all these comments. I think I remember the PS2 having the same thing.
Wistar 5y ago
Yes! I have difficulty with some blue signage and especially with certain intense blue LED lights as they seem to vibrate to my eyes. I also find it hard for me to read the text in blue on the small, scrolling LED signs common in storefronts.
dalmo3 5y ago
> At long last, we can see why the human eye can't focus on blue light At long last indeed. For decades I wondered why blue lights are disturbingly blurry at night, to the point I'd rather not look at them. I always thought it was just me since other people didn't seem to care as much.
- glenngillen 5y ago
  I’ve found my people! I have similar issues and nobody I’ve ever spoken to about it seems to have the same experience. Two similar issues I’ve had, and I’ve wondered if they’re related, are: - at conferences with very large overhead projection sometimes the setup produces an effect where each time I blink it’s like it separates the RGB elements. It’s like a combination of being able to see the refresh rate (like when a CRT was filmed out of sync) and the colours being projected out of alignment. - a stadium near me as those digital display advertising signs around the sidelines. If I’m not looking directly at them they appear to flicker. Which actually makes watching a game at that venue not enjoyable as watching the action means I have a permanent shimmering right on the periphery. Does anybody know what’s happening with either of these?
  - sgtnoodle 5y ago
    That's most certainly the display sequentially flashing red, green and blue sequentially in time to approximate shades and hues. When you stare right at it, your eye averages the photons with a time constant of 1/30th of a second or so, and so you don't perceive the flicker. When you move your eye or blink, though, individual portions of your eye are exposed to only relatively narrow time slices, and so re only exposed to the red, green or blue photons. Cheaper DLP projectors use a single light source and mechanically spin a color wheel with alternating red, green and blue filters. They look great when staring at it, but if you move your head or wave your hand in front of it, you can easily see the three color channels. Perhaps those stadium displays are DLP projectors based, or maybe they're RGB LED and are simply PWMed at a relatively slow rate. Most LEDs can be switched very fast, at say 10Khz, but maybe there's electrical limitations of building such a large high brightness display. If it's only PWMing at 100-200Hz, you'd see similar effects. In particular, each color channel will be on for different duty cycle durations, and LEDs are very fast to turn on and off. So, when you move your eyes or blink, you'll once again get separation of the channels in your vision. You can do a similar trick with your smartphone camera. Record video, and point it at the display then wiggle the phone up and down and side to side. The phone most certainly has a "rolling shutter" which means it captures an image sequentially in lines either horizontally or vertically. It does it quickly, but slow enough that different lines should be able to pick up colors. You may not even need to shake the camera up and down to see a funky image. It's the same reason why CRT monitors and TVs look funky on video but not film.
    - dalmo3 5y ago
      Thanks for the explanation! I can certainly perceive all those flickering effects when moving the eyes. Slow PWM is hell, but some stuff like colour separation can be cool too. My favourite trick is making a digital clock's numbers "slide" over the clock's surface, in a sort of parallax way. I guess that's due to low refresh rates, so for a very brief moment there's a disconnect between the clock's physical position and the last know position of the digits.
      - sgtnoodle 5y ago
- PepPizzazz 5y ago
  I hated blue christmas lights because of this. Also, I couldn't read the time on the stove from any reasonable distance since it used blue LEDs. After LASEK, though, I can see blue LEDs nearly as clearly as everything else. My eye surgery gave me nearly 20/10 vision and the greatest thing I got from it was the ability to read the stove clock from across the room. Lol.
- tokamak-teapot 5y ago
  I had a car with blue and red illumination in the dashboard. It always felt like I couldn’t see it properly - like it was blurred. While I like the colour combination, my next car had orange displays, which always look sharp.
lenkite 5y ago
Does this only affect people with Blue eyes ? As someone with utterly black eyes, I don't have a problem looking at glowing blue signs and don't find them fuzzy either.
- sgtnoodle 5y ago
  I have mostly brown eyes, so no?
- lm28469 5y ago
  Eye color doesn't matter in vision, it's not part of the optical path, its role is the same as an aperture on a camera lens.
  - lenkite 5y ago
    Ok it seemed to me that that the stroma of blue eyes scatters back more light: https://medium.com/@ptvan/structural-eye-color-is-amazing-24f47723bf9a https://medium.com/@ptvan/structural-eye-color-is-amazing-24...
    - ryandamm 5y ago
      Yes, scatters it back out — that light does not enter the pupil or contribute to what that person sees (save probably a vanishingly small amount that is re-scattered in the cornea, which is totally de minimus).
CamperBob2 5y ago
It's true that we don't focus well on blue light sources, but it's also true that this web page does not demonstrate that fact in the slightest.

usefulcat 5y ago

Also the blue LED on a PS3. Those always looked blurry to me. It’s especially obvious because of the adjacent green LED.

farbissina 5y ago
You are so right! I always assumed it was the LED's problem until I started reading all these comments. I think I remember the PS2 having the same thing.

Wistar 5y ago

Yes! I have difficulty with some blue signage and especially with certain intense blue LED lights as they seem to vibrate to my eyes. I also find it hard for me to read the text in blue on the small, scrolling LED signs common in storefronts.

dalmo3 5y ago

> At long last, we can see why the human eye can't focus on blue light At long last indeed. For decades I wondered why blue lights are disturbingly blurry at night, to the point I'd rather not look at them. I always thought it was just me since other people didn't seem to care as much.

glenngillen 5y ago
I’ve found my people! I have similar issues and nobody I’ve ever spoken to about it seems to have the same experience. Two similar issues I’ve had, and I’ve wondered if they’re related, are: - at conferences with very large overhead projection sometimes the setup produces an effect where each time I blink it’s like it separates the RGB elements. It’s like a combination of being able to see the refresh rate (like when a CRT was filmed out of sync) and the colours being projected out of alignment. - a stadium near me as those digital display advertising signs around the sidelines. If I’m not looking directly at them they appear to flicker. Which actually makes watching a game at that venue not enjoyable as watching the action means I have a permanent shimmering right on the periphery. Does anybody know what’s happening with either of these?
- sgtnoodle 5y ago
  That's most certainly the display sequentially flashing red, green and blue sequentially in time to approximate shades and hues. When you stare right at it, your eye averages the photons with a time constant of 1/30th of a second or so, and so you don't perceive the flicker. When you move your eye or blink, though, individual portions of your eye are exposed to only relatively narrow time slices, and so re only exposed to the red, green or blue photons. Cheaper DLP projectors use a single light source and mechanically spin a color wheel with alternating red, green and blue filters. They look great when staring at it, but if you move your head or wave your hand in front of it, you can easily see the three color channels. Perhaps those stadium displays are DLP projectors based, or maybe they're RGB LED and are simply PWMed at a relatively slow rate. Most LEDs can be switched very fast, at say 10Khz, but maybe there's electrical limitations of building such a large high brightness display. If it's only PWMing at 100-200Hz, you'd see similar effects. In particular, each color channel will be on for different duty cycle durations, and LEDs are very fast to turn on and off. So, when you move your eyes or blink, you'll once again get separation of the channels in your vision. You can do a similar trick with your smartphone camera. Record video, and point it at the display then wiggle the phone up and down and side to side. The phone most certainly has a "rolling shutter" which means it captures an image sequentially in lines either horizontally or vertically. It does it quickly, but slow enough that different lines should be able to pick up colors. You may not even need to shake the camera up and down to see a funky image. It's the same reason why CRT monitors and TVs look funky on video but not film.
  - dalmo3 5y ago
    Thanks for the explanation! I can certainly perceive all those flickering effects when moving the eyes. Slow PWM is hell, but some stuff like colour separation can be cool too. My favourite trick is making a digital clock's numbers "slide" over the clock's surface, in a sort of parallax way. I guess that's due to low refresh rates, so for a very brief moment there's a disconnect between the clock's physical position and the last know position of the digits.
    - sgtnoodle 5y ago
PepPizzazz 5y ago
I hated blue christmas lights because of this. Also, I couldn't read the time on the stove from any reasonable distance since it used blue LEDs. After LASEK, though, I can see blue LEDs nearly as clearly as everything else. My eye surgery gave me nearly 20/10 vision and the greatest thing I got from it was the ability to read the stove clock from across the room. Lol.
tokamak-teapot 5y ago
I had a car with blue and red illumination in the dashboard. It always felt like I couldn’t see it properly - like it was blurred. While I like the colour combination, my next car had orange displays, which always look sharp.

lenkite 5y ago

Does this only affect people with Blue eyes ? As someone with utterly black eyes, I don't have a problem looking at glowing blue signs and don't find them fuzzy either.

sgtnoodle 5y ago
I have mostly brown eyes, so no?
lm28469 5y ago
Eye color doesn't matter in vision, it's not part of the optical path, its role is the same as an aperture on a camera lens.
- lenkite 5y ago
  Ok it seemed to me that that the stroma of blue eyes scatters back more light: https://medium.com/@ptvan/structural-eye-color-is-amazing-24f47723bf9a https://medium.com/@ptvan/structural-eye-color-is-amazing-24...
  - ryandamm 5y ago
    Yes, scatters it back out — that light does not enter the pupil or contribute to what that person sees (save probably a vanishingly small amount that is re-scattered in the cornea, which is totally de minimus).

CamperBob2 5y ago

It's true that we don't focus well on blue light sources, but it's also true that this web page does not demonstrate that fact in the slightest.