5 ms·

Your eyes suck at blue

68 points by siim 16y ago

olalonde 16y ago
I wouldn't have thought so given that blue is the favorite color of most people[1]. [1] http://www.joehallock.com/edu/COM498/preferences.html http://www.joehallock.com/edu/COM498/preferences.html
- icegreentea 16y ago
  Not really. Favourite colours have to do more with social and cultural features than your ability to finely distinguish between different shades of said colour. I strongly believe that the proper phrasing for the results should not be "blue is the favorite color of most people" but rather "blue is the favourite colour of most White North Americans/Western Europeans". I bet if this was done in China, it would be more heavily weighted towards red, and if done in ancient Phenoncia, it would probably be purple.
  - eru 16y ago
    Maybe also because `blue' (or `red' or `green') is easy to say. More so than more detailed descriptions of colors.
  - mynameishere 16y ago
    I think this is why people like blue. http://www.flickr.com/photos/lighthearted/37225804/ http://www.flickr.com/photos/lighthearted/37225804/
rix0r 16y ago
> This is how DVDs work: a high res green image and two low-res images, one for red, one for blue. Not true. MPEG-2 uses the YCbCr colorspace, consisting of a high resolution Luminance signal (brightness) and a low resolution Chrominance signal (color). So in fact, all color information is subsampled, green is not treated specially.
- jim_dot 16y ago
  Indeed. The author of this article is pretty badly misinformed.
- kwantam 16y ago
  Green is absolutely treated specially in YCbCr; you just have to understand how YCbCr relates to RGB. ITU-R BT.601 defines YCbCr as follows: Y ~= 0.30 R + 0.59 G + 0.11 B Cb ~= -0.17 R - 0.33 G + 0.5 B Cr ~= 0.5 R - 0.42 G - 0.08 B Y is given the most bandwidth, and green makes up 60% of Y. Cb and Cr are allocated substantially less bandwidth, and green still makes up a sizable chunk of the value. In total, green occupies about 2/3 of the bandwidth in YCbCr. That's pretty much the whole point of doing it---RGB spends an unnecessary amount of bandwidth on R and B. (reference: http://en.wikipedia.org/wiki/YCbCr http://en.wikipedia.org/wiki/YCbCr )
jarin 16y ago
That is pretty neat, although I'm not sure I understand all the outrage. "THE DVD FORUM IS STEALING OUR PIXELS!!" If your eye doesn't notice the difference, are you being "bilked"?
- docgnome 16y ago
  I think it's the same situation as so called "audiophiles" who spend large amounts of money on gold cables and ultra expensive headphones. They may or may not be able to tell the difference but the knowledge that their 10000USD headphones produce a slightly large range of sound than the 100USD pair makes them believe that the more expensive headphones are worth it. In the same way you could probably sell some sort of... DVD re...bluer? or something and make a mint even if no one could tell the difference.
  - jiganti 16y ago
    I'm not sure it would work if no one could tell the difference, and I'll cite your example of the audiophiles. Many people are overpaying for sound equipment that would sound no different to them than stuff half the price, but the fact that there are people that can tell the difference, who talk about that difference constantly, keeps the deluded part of the market in the dark. These people will never do some sort of double-blind test to identify whether or not they can tell the difference, but since there were originally people who could recognize it, others started to follow blindly. There has to be some starting off point before the masses buy into the hype.
mfukar 16y ago
I'm wondering how much of this isn't an artifact of that specific picture; how do we know the RGB distribution in the original pic isn't skewed away from blue? That might explain why there's little information in the blue channel, right? edit: no -> little
bradleyland 16y ago
Ugh. We don't have an entirely clear picture of how our eyes physically detect color, much less how we perceive it, but there are serious problems with the argument the author makes here. You cannot simply take a color photograph of a scene, split it in to three channels, then point out that the blue channel is "dark and contains less detail" as evidence of our inability to perceive the color blue. The fact is that the blue channel really is darker because of the actual lack of blue light in the photo. The trick here is that the areas that have a lot of detail (her face, for example) contain less blue. If you use a color meter to inspect the areas around the girls face, you'll find that there is less blue light present. That makes sense, considering that our skin doesn't contain a lot of blue pigment. This fact is exacerbated by the fact that the author overlaps the channel samples in a way that places emphasis on the areas impacted the most. Basically, the author fails to understand the additive color model. We don't notice the pixelation of the blue channel in this photo because the result of the alteration is to introduce a low-contrast color in to the photo where the aberration overlaps: yellow. If you look closely, you'll see that the areas where you see cyan and magenta in the red and green channels are replaced by yellow in the corresponding blue channel alteration. The effects are diminished by two factors: there isn't much blue luminance present to influence the other colors, and yellow contrasts poorly with most of the colors in the photo where we notice it (the hood is white). If you were to take a color-neutral photograph and split out the RGB channels, you'd perceive the same level of detail in all channels. EDIT: I'd kind of like to take back that last statement about perceiving the same level of detail in all channels. I don't know that you would, but that's not the primary thing that bugs me about the author's argument. My main point is that his argument is flawed, not his assertion. I don't know enough about human color perception to make that argument.
- bradleyland 16y ago
  Anyone curious about how I know there is less blue in the photo should open the photograph in an image editor and inspect the histogram for each channel. If you don't understand color histograms, read my dandy article on the topic: http://upload.bradlanders.com/mycanikon/essays/histograms/html/ http://upload.bradlanders.com/mycanikon/essays/histograms/ht... The article focuses on average luminance, but histograms are interpreted the same for all color channels when looked at individually.
deleted 16y ago
[deleted]
clay 16y ago
This plays into something that Robin Hanson was doing with colors. Blue = Far Mode = grainy, picture unclear and far away. http://www.overcomingbias.com/2010/05/color-meanings.html http://www.overcomingbias.com/2010/05/color-meanings.html
DrStalker 16y ago
Does the article mention that images taken with a digital camera (with a few exceptions) only sample 1/2 the green pixels and 1/4 each of the red and blue ones? http://en.wikipedia.org/wiki/Bayer_filter http://en.wikipedia.org/wiki/Bayer_filter There will be more information in the green channel because that is how the camera is built. I'm sure somewhere there is proper research that was was used in developing the Bayer filter that indicates the human eye is more sensitive to green, but this looks like a case of bad methodology ending up with the right conclusion through luck.
- jkic47 16y ago
  To add to your point, a typical imager pixel can only sense one color - red, green or blue (caveat: there are now some imagers that can simultaneously sense multiple colours). The green value of a non-green pixel is interpolated from the surrounding pixels capable of sensing green. Thus, only 1/3 of your RGB image is "real" - the remaining 2/3 is interpolated.
ajg1977 16y ago
Trivia: DXT compression (the texture compression used in virtually all modern games) uses a 5:6:5 format for end channels giving the green channel the extra bit of precision, for exactly this reason.
iwr 16y ago
Low blue sensitivity may be due to the eye's lens being opaque to UV (very bright blue). This is for good reasons because then daylight illumination would be painful and cause retinal damage over time. The blue color receptor can actually capture a wider range blues and low UV shades. People who had cataract surgery (which replaces the defective lens with an artificial one) may see into these deeper shades of blue if they received an older style of implant. http://www.guardian.co.uk/science/2002/may/30/medicalscience.research http://www.guardian.co.uk/science/2002/may/30/medicalscience...

68 points by siim 16y ago

I wouldn't have thought so given that blue is the favorite color of most people[1]. [1] http://www.joehallock.com/edu/COM498/preferences.html http://www.joehallock.com/edu/COM498/preferences.html

icegreentea 16y ago
Not really. Favourite colours have to do more with social and cultural features than your ability to finely distinguish between different shades of said colour. I strongly believe that the proper phrasing for the results should not be "blue is the favorite color of most people" but rather "blue is the favourite colour of most White North Americans/Western Europeans". I bet if this was done in China, it would be more heavily weighted towards red, and if done in ancient Phenoncia, it would probably be purple.
- eru 16y ago
  Maybe also because `blue' (or `red' or `green') is easy to say. More so than more detailed descriptions of colors.
- mynameishere 16y ago
  I think this is why people like blue. http://www.flickr.com/photos/lighthearted/37225804/ http://www.flickr.com/photos/lighthearted/37225804/

rix0r 16y ago

> This is how DVDs work: a high res green image and two low-res images, one for red, one for blue. Not true. MPEG-2 uses the YCbCr colorspace, consisting of a high resolution Luminance signal (brightness) and a low resolution Chrominance signal (color). So in fact, all color information is subsampled, green is not treated specially.

jim_dot 16y ago
Indeed. The author of this article is pretty badly misinformed.
kwantam 16y ago
Green is absolutely treated specially in YCbCr; you just have to understand how YCbCr relates to RGB. ITU-R BT.601 defines YCbCr as follows: Y ~= 0.30 R + 0.59 G + 0.11 B Cb ~= -0.17 R - 0.33 G + 0.5 B Cr ~= 0.5 R - 0.42 G - 0.08 B Y is given the most bandwidth, and green makes up 60% of Y. Cb and Cr are allocated substantially less bandwidth, and green still makes up a sizable chunk of the value. In total, green occupies about 2/3 of the bandwidth in YCbCr. That's pretty much the whole point of doing it---RGB spends an unnecessary amount of bandwidth on R and B. (reference: http://en.wikipedia.org/wiki/YCbCr http://en.wikipedia.org/wiki/YCbCr )

jarin 16y ago

That is pretty neat, although I'm not sure I understand all the outrage. "THE DVD FORUM IS STEALING OUR PIXELS!!" If your eye doesn't notice the difference, are you being "bilked"?

docgnome 16y ago
I think it's the same situation as so called "audiophiles" who spend large amounts of money on gold cables and ultra expensive headphones. They may or may not be able to tell the difference but the knowledge that their 10000USD headphones produce a slightly large range of sound than the 100USD pair makes them believe that the more expensive headphones are worth it. In the same way you could probably sell some sort of... DVD re...bluer? or something and make a mint even if no one could tell the difference.
- jiganti 16y ago
  I'm not sure it would work if no one could tell the difference, and I'll cite your example of the audiophiles. Many people are overpaying for sound equipment that would sound no different to them than stuff half the price, but the fact that there are people that can tell the difference, who talk about that difference constantly, keeps the deluded part of the market in the dark. These people will never do some sort of double-blind test to identify whether or not they can tell the difference, but since there were originally people who could recognize it, others started to follow blindly. There has to be some starting off point before the masses buy into the hype.

mfukar 16y ago

I'm wondering how much of this isn't an artifact of that specific picture; how do we know the RGB distribution in the original pic isn't skewed away from blue? That might explain why there's little information in the blue channel, right? edit: no -> little

bradleyland 16y ago

Ugh. We don't have an entirely clear picture of how our eyes physically detect color, much less how we perceive it, but there are serious problems with the argument the author makes here. You cannot simply take a color photograph of a scene, split it in to three channels, then point out that the blue channel is "dark and contains less detail" as evidence of our inability to perceive the color blue. The fact is that the blue channel really is darker because of the actual lack of blue light in the photo. The trick here is that the areas that have a lot of detail (her face, for example) contain less blue. If you use a color meter to inspect the areas around the girls face, you'll find that there is less blue light present. That makes sense, considering that our skin doesn't contain a lot of blue pigment. This fact is exacerbated by the fact that the author overlaps the channel samples in a way that places emphasis on the areas impacted the most. Basically, the author fails to understand the additive color model. We don't notice the pixelation of the blue channel in this photo because the result of the alteration is to introduce a low-contrast color in to the photo where the aberration overlaps: yellow. If you look closely, you'll see that the areas where you see cyan and magenta in the red and green channels are replaced by yellow in the corresponding blue channel alteration. The effects are diminished by two factors: there isn't much blue luminance present to influence the other colors, and yellow contrasts poorly with most of the colors in the photo where we notice it (the hood is white). If you were to take a color-neutral photograph and split out the RGB channels, you'd perceive the same level of detail in all channels. EDIT: I'd kind of like to take back that last statement about perceiving the same level of detail in all channels. I don't know that you would, but that's not the primary thing that bugs me about the author's argument. My main point is that his argument is flawed, not his assertion. I don't know enough about human color perception to make that argument.

bradleyland 16y ago
Anyone curious about how I know there is less blue in the photo should open the photograph in an image editor and inspect the histogram for each channel. If you don't understand color histograms, read my dandy article on the topic: http://upload.bradlanders.com/mycanikon/essays/histograms/html/ http://upload.bradlanders.com/mycanikon/essays/histograms/ht... The article focuses on average luminance, but histograms are interpreted the same for all color channels when looked at individually.

deleted 16y ago

[deleted]

clay 16y ago

This plays into something that Robin Hanson was doing with colors. Blue = Far Mode = grainy, picture unclear and far away. http://www.overcomingbias.com/2010/05/color-meanings.html http://www.overcomingbias.com/2010/05/color-meanings.html

DrStalker 16y ago

Does the article mention that images taken with a digital camera (with a few exceptions) only sample 1/2 the green pixels and 1/4 each of the red and blue ones? http://en.wikipedia.org/wiki/Bayer_filter http://en.wikipedia.org/wiki/Bayer_filter There will be more information in the green channel because that is how the camera is built. I'm sure somewhere there is proper research that was was used in developing the Bayer filter that indicates the human eye is more sensitive to green, but this looks like a case of bad methodology ending up with the right conclusion through luck.

jkic47 16y ago
To add to your point, a typical imager pixel can only sense one color - red, green or blue (caveat: there are now some imagers that can simultaneously sense multiple colours). The green value of a non-green pixel is interpolated from the surrounding pixels capable of sensing green. Thus, only 1/3 of your RGB image is "real" - the remaining 2/3 is interpolated.

ajg1977 16y ago

Trivia: DXT compression (the texture compression used in virtually all modern games) uses a 5:6:5 format for end channels giving the green channel the extra bit of precision, for exactly this reason.

iwr 16y ago

Low blue sensitivity may be due to the eye's lens being opaque to UV (very bright blue). This is for good reasons because then daylight illumination would be painful and cause retinal damage over time. The blue color receptor can actually capture a wider range blues and low UV shades. People who had cataract surgery (which replaces the defective lens with an artificial one) may see into these deeper shades of blue if they received an older style of implant. http://www.guardian.co.uk/science/2002/may/30/medicalscience.research http://www.guardian.co.uk/science/2002/may/30/medicalscience...