Why we're blind to the color blue • Hacker News Board

Re: Why we're blind to the color blue

#21

Post by enriquto » Fri, Jul 16, 2021, 5:52 PM UTC

briefcomment wrote: post #3

The second to last demonstration blows my mind. I can't help but feel like I'm being duped, the result is so sharp.

i guess with red you get a similar effect. The green channel is the one that affects most the perceived intensity. If you blur the green everything becomes blurred.

Re: Why we're blind to the color blue

#22

Post by aimor » Fri, Jul 16, 2021, 5:58 PM UTC

I'm tempted to experiment. If I take a blue LED and a green LED in the dark, when I focus on one the other should appear blurred.

Re: Why we're blind to the color blue

#23

Post by klodolph » Fri, Jul 16, 2021, 6:03 PM UTC

aimor wrote: post #22

I'm tempted to experiment. If I take a blue LED and a green LED in the dark, when I focus on one the other should appear blurred.

My experience is that in the dark, I can't focus on a blue LED at all. It will just look a bit blurry.

Re: Why we're blind to the color blue

#24

Post by phnofive » Fri, Jul 16, 2021, 6:04 PM UTC

crazygringo wrote: post #19

I don't believe the blurred images at the end have anything to do with eye focus, as the author suggests. 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 tha…

I agree, in that it was pretty easy to dismiss effects on the example image. Doing this with shapes and a variety of hues and luminances would be a better way to prove the point if it bears out.

Re: Why we're blind to the color blue

#25

Post by klodolph » Fri, Jul 16, 2021, 6:04 PM UTC

seunosewa wrote: post #16

I'd like to see what happens when the red channel is blurred. Digital images like JPGs seem to blur the red channel more than the blue and green channels.

JPEG transforms the color into YUV channels. Y is the luminance, equal to R+G+B or something like that. The U&V channels (color) are often downsampled.

Re: Why we're blind to the color blue

#26

Post by floatrock » Fri, Jul 16, 2021, 6:10 PM UTC

aimor wrote: post #22

I'm tempted to experiment. If I take a blue LED and a green LED in the dark, when I focus on one the other should appear blurred.

Blue LED clocks (like on 'high end' microwaves or appliances) are one of my biggest pet peeve. I'm not an old fart by any stretch -- my eyes are fine -- but the blue blur when looking at the clock at night is a real thing.

Fun fact: this phenomenon is similar to why older cars had yellow-tinged fog lights. It's partly light scattering in suspended water droplets (fog), it's partly the perception factors talked about in the article, but basically reds and yellows have lowest "light scatter". You're not gonna build a red foglight for red-is-danger reasons, so yellow foglights are the next best thing.

Re: Why we're blind to the color blue

#27

Post by ulrikrasmussen » Fri, Jul 16, 2021, 6:13 PM UTC

That explains beautifully why I always feel like I've lost my contact lenses when I'm at a concert and the lighting goes all blue.

Re: Why we're blind to the color blue

#28

Post by isatty » Fri, Jul 16, 2021, 6:13 PM UTC

crazygringo wrote: post #19

I don't believe the blurred images at the end have anything to do with eye focus, as the author suggests. 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 tha…

I think that the title is a massive oversimplification because chromatic aberration by itself is not enough for us to be blind to the color blue. We do have cones that can detect blue for one.

We are however, less sensitive to it so maybe the eye doesn't focus based on that channel(?).

Re: Why we're blind to the color blue

#29

Post by crdrost » Fri, Jul 16, 2021, 6:13 PM UTC

crazygringo wrote: post #19

I don't believe the blurred images at the end have anything to do with eye focus, as the author suggests. 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 tha…

I'm not sure you're right. At night both I and my wife have reported difficulty reading glowing blue signs compared to glowing red/green signs at the same font size, brightness, and distance.

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.

Re: Why we're blind to the color blue

#30

Post by lordnacho » Fri, Jul 16, 2021, 6:13 PM UTC

This would seem to explain why when you go to the optician, he's got a lot of red/green tests but never blue one as far as I can tell. The critical graph is the one with the blue peak to the left and the red and green near each other on the right.

Also it seems to hint that there's a fourth receptor that humans don't have in the gap region. Tetra-chromatic creatures do exist IIRC.