>> And yet, when I look outside, the world is /not/ tinged blue. So... WTH?
>
> Because there's usually a light_source{ <0,0,0> color Yellow*6500 } in
> the scene.

So I just need to turn up the Sun a bit higher and make it more yellow?

> Look at shadows on snow or on a beach, they'll be blue.
>
>
http://www.free-desktop-backgrounds.net/free-desktop-wallpapers-backgrounds/free-hd-desktop-wallpapers-backgrounds/122079702.jpg
>
> http://www.amandapair.com/wp-content/uploads/2009/09/shadows-in-sand.jpg

Those are some neat images. They both look like the Sun is quite low in 
the sky though; and we all know that when that happens, you can get 
strange colours happening.

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On 15/06/2012 04:28 PM, Warp wrote:
> Invisible<voi### [at] devnull>  wrote:
>> And yet, when I look outside, the world is /not/ tinged blue. So... WTH?
>
>    Actually it is. Consider this rendering, for example:
>
> http://www.ignorancia.org/uploads/images/rocky-desert/rocky-desert-09-sbtf.jpg
>
>    Everything's tinted blue. Does it look unrealistic? No.

Uh... doesn't actually look all that blue to me.

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Le 15/06/2012 17:14, Warp nous fit lire :
>   The sun is not yellow. It's white.

Well, Superman said it's a yellow star it get its powers from. Who are
we to challenge him ?

Astronomically, the sun is in the yellow star category (strictly, it's a
yellow dwarf, G2V). A white dwarf is far more 'hot' (but they cool down
with time).

But I will concede that the sun is rather a white one in that yellow
category, and the yellow we see is due to Rayleigh scattering (which is
also the cause of daylight blue sky and other colours at dawn...)

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Orchid Win7 v1 <voi### [at] devnull> wrote:
> On 15/06/2012 04:28 PM, Warp wrote:
> > Invisible<voi### [at] devnull>  wrote:
> >> And yet, when I look outside, the world is /not/ tinged blue. So... WTH?
> >
> >    Actually it is. Consider this rendering, for example:
> >
> > http://www.ignorancia.org/uploads/images/rocky-desert/rocky-desert-09-sbtf.jpg
> >
> >    Everything's tinted blue. Does it look unrealistic? No.

> Uh... doesn't actually look all that blue to me.

  Significantly bluer than if the sky weren't.

-- 
                                                          - Warp

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Am 15.06.2012 17:14, schrieb Warp:
> Le_Forgeron<jgr### [at] freefr>  wrote:
>> If the sky is "blue", why do you see a yellow sun ?
>
>    The sun is not yellow. It's white.

That depends on the color space.

In sRGB (whitepoint = D65 = ~6500K), the sun is a pale yellow.

In Wide Gamut RGB (Whitepoint = D50 = ~5000K), the sun is actually a 
pale blue.

If you use a color space with the equal-energy point (E) as whitepoint, 
the sun is even a pale green.


That's both for the sun's /actual/ color (without atmospheric effects, 
i.e. as seen from space) of ~5900K, as well as the sun's apparent color 
on earth at daytime of ~5500K.

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On 6/15/2012 8:14 AM, Warp wrote:
> Le_Forgeron<jgr### [at] freefr>  wrote:
>> If the sky is "blue", why do you see a yellow sun ?
>
>    The sun is not yellow. It's white.
>
Umm. Actually, this page says, if it was a "blackbody", it would be 
closest to, "It looks peach pinkish, not yellow, doesn't it?"

http://casa.colorado.edu/~ajsh/colour/Tspectrum.html

So, still not "yellow", but damn sure not "white".

But, still a damn site more confusing than any exist "chart" I have ever 
seen, with respect to star colors. In general, once it scatters in the 
atmosphere, the light we get ends up closer to what we would call white, 
with a pale bluish tint, hence the bluish tint on some of the newer, 
"closer to real", light bulbs.

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On 6/15/2012 10:48 AM, clipka wrote:
> Am 15.06.2012 17:14, schrieb Warp:
>> Le_Forgeron<jgr### [at] freefr> wrote:
>>> If the sky is "blue", why do you see a yellow sun ?
>>
>> The sun is not yellow. It's white.
>
> That depends on the color space.
>
> In sRGB (whitepoint = D65 = ~6500K), the sun is a pale yellow.
>
> In Wide Gamut RGB (Whitepoint = D50 = ~5000K), the sun is actually a
> pale blue.
>
> If you use a color space with the equal-energy point (E) as whitepoint,
> the sun is even a pale green.
>
>
> That's both for the sun's /actual/ color (without atmospheric effects,
> i.e. as seen from space) of ~5900K, as well as the sun's apparent color
> on earth at daytime of ~5500K.
Umm. So which color space is this one: 
http://www.vendian.org/mncharity/dir3/starcolor/ lol

Though, it appears to be the D65, but with the color actually being 
"slightly off" that value, enough that it gets more.. peach colored.

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On 6/15/2012 8:28 AM, Warp wrote:
> Invisible<voi### [at] devnull>  wrote:
>> And yet, when I look outside, the world is /not/ tinged blue. So... WTH?
>
>    Actually it is. Consider this rendering, for example:
>
> http://www.ignorancia.org/uploads/images/rocky-desert/rocky-desert-09-sbtf.jpg
>
>    Everything's tinted blue. Does it look unrealistic? No.
>
Uh.. Think you need to adjust your display. That looks completely normal 
to me.

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Am 15.06.2012 19:48, schrieb clipka:
> Am 15.06.2012 17:14, schrieb Warp:
>> Le_Forgeron<jgr### [at] freefr> wrote:
>>> If the sky is "blue", why do you see a yellow sun ?
>>
>> The sun is not yellow. It's white.
>
> That depends on the color space.
>
> In sRGB (whitepoint = D65 = ~6500K), the sun is a pale yellow.
>
> In Wide Gamut RGB (Whitepoint = D50 = ~5000K), the sun is actually a
> pale blue.
>
> If you use a color space with the equal-energy point (E) as whitepoint,
> the sun is even a pale green.
>

This makes actually not much sense as all RGB-color-spaces are device 
dependent. So when you use e.g. WideGamut RGB or Adobe RGB as a 
*viewing* color space with a sRGB device you are obviously doing 
something very wrong.


> That's both for the sun's /actual/ color (without atmospheric effects,
> i.e. as seen from space) of ~5900K, as well as the sun's apparent color
> on earth at daytime of ~5500K.

Close ;)

See attachment, the output from test_sun.pov (a POV-Ray scene file I've 
written for lightsys IV - at www.ignorancia.org) that compares the 
actual spectral data with the blackbody radiation. I think there is also 
an espd*.inc file for the sun filtered by earth atmosphere, for people 
who want to play around with it.

I've just noticed (quite surprised) that the file is from April 2003, 
doesn't time fly by...

-Ive

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Attachments:
Download 'test_sun.png' (176 KB)

Preview of image 'test_sun.png'

Am 16.06.2012 11:24, schrieb Ive:
> Am 15.06.2012 19:48, schrieb clipka:
>> Am 15.06.2012 17:14, schrieb Warp:
>>> Le_Forgeron<jgr### [at] freefr> wrote:
>>>> If the sky is "blue", why do you see a yellow sun ?
>>>
>>> The sun is not yellow. It's white.
>>
>> That depends on the color space.
>>
>> In sRGB (whitepoint = D65 = ~6500K), the sun is a pale yellow.
>>
>> In Wide Gamut RGB (Whitepoint = D50 = ~5000K), the sun is actually a
>> pale blue.
>>
>> If you use a color space with the equal-energy point (E) as whitepoint,
>> the sun is even a pale green.
>
> This makes actually not much sense as all RGB-color-spaces are device
> dependent. So when you use e.g. WideGamut RGB or Adobe RGB as a
> *viewing* color space with a sRGB device you are obviously doing
> something very wrong.

You should know better (or I'm misunderstanding you).

sRGB is not a device-dependent color space.
WideGamut RGB is not a device-dependent color space.
Adobe RGB is not a device-dependent color space.

My EIZO S2402W's color space is device-dependent, yes.

The panel of an individual EIZO CG245W has its own device-dependent 
color space, but the EIZO CG245W as a finished product can be calibrated 
to various different standard or non-standard color profiles (with some 
limitations imposed by the panel's gamut of course).

There are device-dependent color spaces, and there are 
device-independent color spaces. The standard color spaces are, 
obviously, device-independent.

But I'm sure I'm not telling you anything new.

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