If it really was the effect of blue light, the effect should have disappeared by converting to grayscale.
It is well known that luminance matters much more than color when it comes to perceived sharpness. Digital and analog video exploit that by encoding color at a lower resolution (chroma subsampling). And blue only accounts for less that 10% of luminance while green is around 70%. You may find different values because color spaces are a mess but that's the general idea.
Which really illustrates why TFA doesn't make any sense- our eyes are less sensitive to blue, so the contrast provided by max RGB value blue is going to be completely drowned out by red and green if the source of your contrast is white on black.
Here's what it looks like with all channels shifted to have the same luminance: https://i.imgur.com/AnKNdfX.jpg - note it is perhaps a little softer as the peak brightness is closer to black.
Now here's what each channel looks like blurred by 2.5px: https://i.imgur.com/XzVWeZg.jpg https://i.imgur.com/LB5JArJ.jpg https://i.imgur.com/jf4ntth.jpg
They're all clearly fuzzy in comparison to the un-blurred image. The answer to "why we're blind to the color blue" is not chromatic aberration (although it could be a contributing factor, maybe even why we have less blue receptors), it's that we're less sensitive to blue and therefore contrast is usually defined by red and green.
Personally I don’t see each image as equally blurred, but YMMV.
Where I've noticed weird things with blue are with blue sources that have fairly short wavelengths, such as some of the blue LEDs used in Xmas tree lights, and the old blue lights that were on police call boxes. Both of those are very hard for me to focus on.
This happens to me as well and I though I was becoming blind (to blue light) because of my heavy use of monitors/"white" light, etc...
Here are my results, with a 22px Gaussian Blur on the Channels
IMO The only reason the blue appears a little less blurry is that most of that color is in the water & clouds.
Not in the land masses, with the sharp borders
Y' = 0.2126R' + 0.7152G' + 0.0722B'And colured versions: https://imgur.com/a/Knq2Ue3
(image source: https://en.wikipedia.org/wiki/Flower#/media/File:Flower_post...)
So even if blue is 1/10th or 1/3rd as strong as another color, it's not really a big deal in terms of sensitivity.
Instead it's like log(R/3 + G + B/10). So when G and B are about the same size, the effect of B will be negligible. It's only when R and G are small that the logarithm will kick in and let you see detail using the blue.
So for seeing detail in a normal picture, blurring the green will have a much larger effect than blurring the blue. But entirely removing the green would let it still look sharp, because we could see the detail using the red (or if we removed that, then blue). If we just blur the green it overwhelms the blue and red to make the picture look blurry even if the blue and red were enough to provide sharp detail if the green wasn't there.
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.
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?
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.
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.
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.
While I like the colour combination, my next car had orange displays, which always look sharp.
http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.ht...
I'm also not sure that the author is correct; the wrong-focal-distance explanation seems rather weak simply because our focal length is adjustable.
Blue LEDs in clocks when viewed at night look completely fucked up.
crdrost described their vision problems, jbluepolarbear said "you have astigmatism", techrat popped in and said "[I have] no astigmatism" and jbluepolarbear made a more general statement that most people do.
I'd assume techrat doesn't know anything about crdrost's vision either.
Signed, a dude with very slight astigmatism :)
Bruh. Read the comment of mine you replied to. 20/10 and 20/13 vision. I don't need prescriptions.
I could totally believe the someone might have "perfect" vision that doesn't require correction, but still have a slight astigmatism that impacts their vision under certain specific scenarios such as when viewing blue LEDs in low light.
I'm not necessarily saying that's what you have, but more just that to the extent your eyes have been evaluated, it was likely "yeah they look great as far as your ability to perceive the brightly lit eye chart, no need to do the more detailed analysis where we figure out the other parameters that will never be used because you're fine, bye."
This whole thread is silly.
If we're doing dumb analogies, it's like you're trying to insist a homeless man must have an address.
Off topic, but I'm jumping around a bit tonight.
https://my.clevelandclinic.org/health/diseases/8576-astigmat...
One thing is that the ocean is hardly blue. Not sure why my eyes register it as such, but it's mostly very close to black with nearly equal parts of red and green, at least the parts I sampled. I think a certain amount of this article's claim is predicated on the reader erroneously believing the ocean should become blurry.
We are however, less sensitive to it so maybe the eye doesn't focus based on that channel(?).
I suspect that a plausible cause could be that there just aren't a lot of blue receptors in the retina, as the eye is pretty insensitive to blue overall.
That description doesn't do it justice - you have to experience it to appreciate it. It's very striking and slightly surreal.
After all, chromatic aberration is blurring of only a very, very small amount.
The demonstrated seemingly negligible perceptual effect of blurring blue to a huge degree in a multicolor image doesn't seem to have anything to do with that, but rather the fact that we perceive primary blue as a much darker color than primary red or green, and we perceive differences in lighter colors much more easily.
If the author were correct that we have big problems focusing on blue, then we'd see that blue text against a black background would be massively blurry -- but it's simply not. It's comparatively low-contrast (because blue is a dark color), but it's nearly indistinguishably as sharp as red and green.