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Why we're blind to the color blue

calebkruse.com

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Re: Why we're blind to the color blue

#161

Post by perl4ever »

techrat wrote: post #106
jbluepolarbear wrote: post #102

Earlier quoted context omitted.

9 in 10 people have some affliction of astigmatism. Astigmatism is just that your eye isn’t perfectly spherical. What does your eye prescription say in the cyl and axis fields, that’s your astigmatism correction.

'eye prescription'? Bruh. Read the comment of mine you replied to. 20/10 and 20/13 vision. I don't need prescriptions.

I think more than one person has confused you with the person a couple levels up thread, i.e. https://news.ycombinator.com/item?id=27859324

Re: Why we're blind to the color blue

#162

Post by skupig »

Retric wrote: post #145
GuB-42 wrote: post #141

Earlier quoted context omitted.

Right, I picked the "blurred blue" and "blurred green" pictures, converted them to grayscale using luminance and "blurred blue" still looks sharp and "blurred green" still looks blurry. 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 expl…

That’s not an apples to apples test because of how greyscale is computed. Try swapping the blue and green channels rather than converting to greyscale.

I think for a proper comparison, you would need to swap them by perceived brightness (luminance), not just the RGB value. You can't do that here because the green channel in this image is out of the possible range of luminance you can achieve with blue (in any standard color space, probably).

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.

Re: Why we're blind to the color blue

#163

Post by tigershark »

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…

Exactly. In the real life I find very difficult to focus on violet signs against the black night background, but it’s a completely different effect from the one in this article and it’s exacerbated by the bigger pupil diameter in the night that increases the aberration.

Re: Why we're blind to the color blue

#164

Post by throwasquirrel »

tcmb wrote: post #69
jbluepolarbear wrote: post #63

Earlier quoted context omitted.

I’ve never met anyone without some astigmatism; especially, people with other vision impairment. Astigmatism is the number one cause of night blindness which is what you described.

HN is so funny. 'I have no astigmatism.' -- 'Sure you do!'

It's right up there with 'I've been clinically diagnosed with ADHD by a qualified psychiatrist and this medication has improved my life tremendously' -- 'There's no such thing, the medication doesn't do anything and you just need to mediate more, have you tried mindfulness?'

Re: Why we're blind to the color blue

#165

Post by Retric »

skupig wrote: post #162
Retric wrote: post #145

Earlier quoted context omitted.

That’s not an apples to apples test because of how greyscale is computed. Try swapping the blue and green channels rather than converting to greyscale.

I think for a proper comparison, you would need to swap them by perceived brightness (luminance), not just the RGB value. You can't do that here because the green channel in this image is out of the possible range of luminance you can achieve with blue (in any standard color space, probably). Which really illustrates why TFA doesn't make any sense- our eyes are less sensitive to blue, so the contrast provided by max…

Perceived brightness is very tricky as our vision naturally adjusts to normalize perceived colors. https://en.wikipedia.org/wiki/The_dress

Personally I don’t see each image as equally blurred, but YMMV.

Re: Why we're blind to the color blue

#166

Post by crazygringo »

rob74 wrote: post #110
bioplastic wrote: post #98

Earlier quoted context omitted.

Indeed, green contributes more. Example of the Y channel after blurring r/g/b: https://imgur.com/a/3p15Qe1 And colured versions: https://imgur.com/a/Knq2Ue3 (image source: https://en.wikipedia.org/wiki/Flower#/media/File:Flower_post... )

More, as in 10 times more for green, and 3 times more for red. So it's true that we're pretty blind to blue, just the "focusing" explanation is not correct...

Except that our perception of brightness, like loudness, is logarithmic, not linear.

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.

Re: Why we're blind to the color blue

#167

Post by stkdump »

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…

Maybe the (evolutional) reason that we perceive blue as darker is exactly that it would otherwise reduce the sharpness of what we see.

Re: Why we're blind to the color blue

#168

Post by glenngillen »

dalmo3 wrote: post #154
sgtnoodle wrote: post #133

Earlier quoted context omitted.

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.

> 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.

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?

Re: Why we're blind to the color blue

#169

Post by salawat »

Talanes wrote: post #155
washadjeffmad wrote: post #117

Earlier quoted context omitted.

That's like saying you can run a 3 minute mile so you don't have a shoe size. This whole thread is silly.

Shoe size is an inherent byproduct of having feet of a certain dimension. A prescription has to be prescribed. If we're doing dumb analogies, it's like you're trying to insist a homeless man must have an address.

...Actually, that's a real problem in the financial services sector. You can't satisfy KYC requirements without an address of record.

Off topic, but I'm jumping around a bit tonight.

Re: Why we're blind to the color blue

#170

Post by analog31 »

GuB-42 wrote: post #141
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…

Right, I picked the "blurred blue" and "blurred green" pictures, converted them to grayscale using luminance and "blurred blue" still looks sharp and "blurred green" still looks blurry. 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 expl…

There's a difficulty with testing perceived color by using a computer display, which is that the "blue" is the spectrum of the blue pixels, whereas the "blue" receptors in your eye may have a different spectral response.

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.

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