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Your eyes suck at blue (neat image compression trick)

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Re: Your eyes suck at blue (neat image compression trick)

#11

Post by tesseract »

Avshalom wrote: post #10
rfurmani wrote: post #4

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…

> 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.

Re: Your eyes suck at blue (neat image compression trick)

#12

Post by teuobk »

Avshalom wrote: post #10
rfurmani wrote: post #4

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…

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.

Re: Your eyes suck at blue (neat image compression trick)

#13

Post by lbrandy »

indiv wrote: post #5

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.

Re: Your eyes suck at blue (neat image compression trick)

#14

Post by asmosoinio »

a-priori wrote: post #9
zain wrote: post #6

Earlier quoted context omitted.

Blueberries?

Blueberries are native only to North America, so our hominid ancestors would not have encountered them. 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...

Re: Your eyes suck at blue (neat image compression trick)

#15

Post by philwelch »

Avshalom wrote: post #10
rfurmani wrote: post #4

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…

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.

Re: Your eyes suck at blue (neat image compression trick)

#16

Post by jballanc »

tesseract wrote: post #11
Avshalom wrote: post #10

Earlier quoted context omitted.

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…

> 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.

To prevent overheating and excessive evaporation, of course...

Re: Your eyes suck at blue (neat image compression trick)

#17

Post by Avshalom »

philwelch wrote: post #15
Avshalom wrote: post #10

Earlier quoted context omitted.

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…

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.

Re: Your eyes suck at blue (neat image compression trick)

#20

Post by jobenjo »

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?

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