Your eyes suck at blue (neat image compression trick)(nfg.2y.net)
nfg.2y.net
Your eyes suck at blue (neat image compression trick)
http://nfg.2y.net/games/ntsc/visual.shtm
27 comments
In more detail: http://en.wikipedia.org/wiki/Chroma_subsampling
The inherent assumption on which chroma sub-sampling is founded is that luminance information is far more important than chromanance information. This is backed up by empirical evidence. From there, the effect follows directly from the equation for luminance:
Y = 0.2126 R + 0.7152 G + 0.0722 B
From here you can see that green is by far the most important color, followed by red, and then finally, way down there, blue.
Y = 0.2126 R + 0.7152 G + 0.0722 B
From here you can see that green is by far the most important color, followed by red, and then finally, way down there, blue.
Umm... I feel like there's a huge flaw in this. He's looking at the different _channels_ in this image, but couldn't that mean there's just less blue data in that particular image?
I believe that humans may be worse at seeing blue, but this test seems bogus. By looking at the channels, he's actually cutting out different subsections of data, so it's apples to oranges, right? What if there's just much less blue in this particular photo?
Or am I mistaken?
I believe that humans may be worse at seeing blue, but this test seems bogus. By looking at the channels, he's actually cutting out different subsections of data, so it's apples to oranges, right? What if there's just much less blue in this particular photo?
Or am I mistaken?
No, You're spot on.
The author states that this is "an unmodified picture, straight off the digicam". Unfortunately for his test, this means the light passed through a Bayer filter, which uses a pattern of "50% green, 25% red and 25% blue": http://en.wikipedia.org/wiki/Bayer_filter
The author states that this is "an unmodified picture, straight off the digicam". Unfortunately for his test, this means the light passed through a Bayer filter, which uses a pattern of "50% green, 25% red and 25% blue": http://en.wikipedia.org/wiki/Bayer_filter
It could, but you can verify that our eyes cannot detect loss of blue information even in the parts of the image that are rather blue (her wristwatch, the car in the background, the edge of the windshield, the stripe on the towel).
In each of those cases fidelity is more damaged by loss of quality in the other
In each of those cases fidelity is more damaged by loss of quality in the other
Interesting. Until reading this, I never stopped to wonder why OpenGL, for example, has GL_UNSIGNED_SHORT_5_6_5 (5 bits for red and blue; six for green) as opposed to some other allocation of 16 bits.
Wow - green, the middle of the visual spectrum matters most. If only they had discovered this years ago there could have been some really good systems for sending color information by just doing intensity-red and intensity-blue.
Or Y-U + Y-V = YUV if you prefer.
I would have started by reducing the bit depth of blue, rather than pixel width.
Ah, but the blue receptors in your eye are as accurate as the green ones, just less tightly packed. Spatial filtering therefore preserves more-visible color accuracy at the expense of less-visible blue location.
Not that that stops all those standards that use reduced bit depth for red and blue.
Not that that stops all those standards that use reduced bit depth for red and blue.
That makes a lot of sense. When we lived in the wild discerning different shades of green would have been crucial. It is also known that women can see more shades of red, probably in order to be able to more effectively gather edible berries. Now blue, who needs it? ;-)
No, sorry that's just nonsense.
We're less sensitive to blue light because there is less blue light.
The black body spectrum of the sun peaks at green (which is why plants are green) and tails of into red. Blue light is not only a proportionately small section of the energy output but blue photons have more energy per particle and so there are even fewer photons necessary to make up that section.
That said while I've heard the women have better red resolution that doesn't necessarily mean they're more sensitive to the color number one. and number two explanations like "so they could gather berries" tend to come from a desire to see women barefoot and pregnant rather than solid science.
We're less sensitive to blue light because there is less blue light.
The black body spectrum of the sun peaks at green (which is why plants are green) and tails of into red. Blue light is not only a proportionately small section of the energy output but blue photons have more energy per particle and so there are even fewer photons necessary to make up that section.
That said while I've heard the women have better red resolution that doesn't necessarily mean they're more sensitive to the color number one. and number two explanations like "so they could gather berries" tend to come from a desire to see women barefoot and pregnant rather than solid science.
> The black body spectrum of the sun peaks at green (which is why plants are green)
Plants are green because they reflect green light, i.e. they do not absorb it and use it to facilitate photosynthesis. Chlorophylls tend to have absorption peaks in the red and blue, which are (in the grand scheme of the electromagnetic spectrum) near the sun's blackbody peak but do not coincide with it.
Plants are green because they reflect green light, i.e. they do not absorb it and use it to facilitate photosynthesis. Chlorophylls tend to have absorption peaks in the red and blue, which are (in the grand scheme of the electromagnetic spectrum) near the sun's blackbody peak but do not coincide with it.
To prevent overheating and excessive evaporation, of course...
Although the black-body spectrum of the sun does peak at green, that's not why plants are green. Consider this: they appear green to us because they are not absorbing the green light.
So, then, why green? For that matter, why not black? Apparently, there's some speculation that early microbes were purple, which meant that they absorbed the green light. Chlorophyll might have appeared only in later microbes, so it would have needed to absorb what was left; namely, red and blue light.
So, then, why green? For that matter, why not black? Apparently, there's some speculation that early microbes were purple, which meant that they absorbed the green light. Chlorophyll might have appeared only in later microbes, so it would have needed to absorb what was left; namely, red and blue light.
This begs the question: why were the microbes purple?
The evidence does seem to suggest that in hunting-gathering communities, women engaged in more gathering and men engaged in more hunting. Claims that otherwise reasonable hypotheses "come from a desire to see women barefoot and pregnant" tend to come from a desire to justify the unquestioned a priori belief that men and women are mostly identical rather than solid science.
HOWEVER
many if not most cultures supplement their diet with roots, tubers, grains and insects.
most edible plants are not red
most fruits and berries are not red
many poisonous things in nature are red
many herbivorous animals are colorblind implying little advantage to strong color vision as far as eating plants go.
all of which is to say: "It is also known that women can see more shades of red, probably in order to be able to more effectively gather edible berries." needs a hell of a lot of evidence to be more than mere speculation, because all of the non-speculation says absolutely nothing about the use of red-resolution.
And as a side note the number of largely color blind apex predators implies that "When we lived in the wild discerning different shades of green would have been crucial." is unsupported as well.
many if not most cultures supplement their diet with roots, tubers, grains and insects.
most edible plants are not red
most fruits and berries are not red
many poisonous things in nature are red
many herbivorous animals are colorblind implying little advantage to strong color vision as far as eating plants go.
all of which is to say: "It is also known that women can see more shades of red, probably in order to be able to more effectively gather edible berries." needs a hell of a lot of evidence to be more than mere speculation, because all of the non-speculation says absolutely nothing about the use of red-resolution.
And as a side note the number of largely color blind apex predators implies that "When we lived in the wild discerning different shades of green would have been crucial." is unsupported as well.
See? Basing an argument on actual evidence proves your point better than basing your argument on some political agenda. "It's unlikely that women have higher red-resolution because many herbivores and apex predators are colorblind" is an actual argument. "It's unlikely that women have higher red-resolution because that claim is made by misogynists" is just a politically charged ad hominem. It'll get you brownie points in the Women's Studies department, but it's still a crap argument.
Okay see I remember seeing the article that made the berry link. Like actual honest to god degree holding scientists (of some discipline) were willing to be quoted on that hypothesis. A hypothesis that I, completely out of my field, just poked a half a dozen major holes in.
I didn't "It's unlikely that women have higher red-resolution because that claim is made by misogynists," I said the berry explanation may have been made by misogynists. I suspect at the very least it was made by morons.
But despite your seeming distaste for Women's Studies, academia has a well documented history of misogyny that needs to be remembered anytime an argument is made that is so close to "women are physically adapted to housework." Particularly when, like I said above, a lack of evidence for some claim is blatantly obvious.
I didn't "It's unlikely that women have higher red-resolution because that claim is made by misogynists," I said the berry explanation may have been made by misogynists. I suspect at the very least it was made by morons.
But despite your seeming distaste for Women's Studies, academia has a well documented history of misogyny that needs to be remembered anytime an argument is made that is so close to "women are physically adapted to housework." Particularly when, like I said above, a lack of evidence for some claim is blatantly obvious.
More generally, it can be said that academia has a well documented history of basing claims on some sort of social or political assumption or agenda. Increasingly, those have come to include liberal agendas like feminism and racial equality. The solution is not increased political consciousness (all that accomplishes is exchanging one political bias for another) but rather better application of the scientific principles we already have.
Blueberries?
Blueberries are native only to North America, so our hominid ancestors would not have encountered them.
http://en.wikipedia.org/wiki/Blueberry
http://en.wikipedia.org/wiki/Blueberry
But bilberry looks quite the same to me -- didn't know the difference until now -- and grows in a lot more places.
http://en.wikipedia.org/wiki/Bilberry
Not that this has anything to do with the original topic...
http://en.wikipedia.org/wiki/Bilberry
Not that this has anything to do with the original topic...
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Might want to bookmark this and check it out later, after the HN traffic surge has died down.