Do white coloured objects reflect infrared radiation?

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Offline Chemistry4me

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Offline yor_on

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Do white coloured objects reflect infrared radiation?
« Reply #1 on: 29/01/2009 03:41:02 »
When using illumination it should be visible.
It's just like any other light.

I think??

You know, photons bouncing, having a good time..
Or am I missing something here?
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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #2 on: 29/01/2009 03:45:32 »
I don't know, you're the physicist, you tell me, please [:)]

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Offline yor_on

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Do white coloured objects reflect infrared radiation?
« Reply #3 on: 29/01/2009 04:05:22 »
Night intensifiers work differently though.
"They focuses the light (photons) on a 'photocathode'.
The cathode release electrons which are then are 'energized' by bouncing around in a electric field as well as generating even more electrons by specially coated walls.. This makes for a denser electron cloud representing an intensified version of the original image.

And they are passive.

Just like cooled infrared detectors.
Cooling the detectors to around -160 C gives them a very extreme sensitivity and without that cooling the detectors would be flooded by their own radiation.
It's only like ten percent of the light from the Sun that comes down as infra red radiation.
So there is not much around:)

But if you're thinking of 'thermal night vision' which also are in the infra red spectrum you are making excellent sense, as well as making me curious:)
That as all living tissue emit infrared energy (temperature).
Those can see through both smoke and fog.
And those are also 'passive' 


If you use such then white materials absorb the least 'heat' and therefore will be hardest to 'see'.
Or if you use material created to contain infra red (heat).
What do you need it for?

--------

Ah, Mr Chem.
Nope, I'm not.

But it was a nice idea.
Thanks
« Last Edit: 29/01/2009 04:09:58 by yor_on »
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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #4 on: 29/01/2009 04:07:57 »
I don't need it for anything, I was just being curious. [:)]

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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #5 on: 29/01/2009 04:10:25 »
But if you're thinking of 'thermal night vision' which also are in the infra red spectrum you are making excellent sense, as well as making me curious:)
What is this? You know a lot more about it than me, I'm curious as to what you are thinking too!

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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #6 on: 29/01/2009 04:11:26 »
What? You're not a physicist? [???][???][???]

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Offline yor_on

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Do white coloured objects reflect infrared radiation?
« Reply #7 on: 29/01/2009 04:14:50 »
Looking at what I wrote, I think there is a 'curse' on me.
It's called 'modify' at this site:)

That's why I need to learn how to spell.
Each one his own warlock:)

And no, you know an awful lot of chemistry right:)
Do you work with it?
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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #8 on: 29/01/2009 04:16:46 »
No, I do not work with chemistry, and I don't know an awful lot about it either!!
You're just a fan of physics right Mr. yor_on?

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Offline yor_on

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Do white coloured objects reflect infrared radiation?
« Reply #9 on: 29/01/2009 04:19:32 »
Well we're both 'fans' I think.
You're a fan of primary Chemistry if I understand you right?

I'm more 'physical'.
No big difference there.

Together we will conquer:)
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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #10 on: 29/01/2009 04:21:52 »
Primary chemistry? What do you mean by that?

Together we will conquer:)
Yes, indeed.

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Offline yor_on

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Do white coloured objects reflect infrared radiation?
« Reply #11 on: 29/01/2009 04:25:35 »
Well your name gave me a clue I have to admit.
As well as this:)
http://www.thenakedscientists.com/forum/index.php?topic=11612.msg221718#msg221718
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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #12 on: 29/01/2009 04:27:44 »
Okay, it is the only thing that I know!!

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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #13 on: 29/01/2009 04:29:37 »
Shouldn't you get some rest Mr. yor_on?

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Offline yor_on

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Do white coloured objects reflect infrared radiation?
« Reply #14 on: 29/01/2009 04:40:19 »
Aha, was it a quiz.

Nah, it's cool, thermally speaking:)
I'll sleep tomorrow:)

Tell me, do you have an inkling for the sweet and 'leisury' life of the armed forces?
It's just an impression I got from a former conversation.
I can't help but wonder.

-------
Btw: that flag?
Shouldn't it be Swedish?



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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #15 on: 29/01/2009 04:45:49 »
Sweet and 'leisury' life aye?? No, I am not planning to join the SAS any time soon!! [:)]
Yeah, sorry, I couldn't find a Swedish flag. [:I][:I]

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Offline yor_on

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« Reply #16 on: 29/01/2009 04:50:42 »
Doesn't matter:)

Otherwise i've heard that some of the best soldiers come from 'under there'
(Kiwis and Maoris:)

Australia have their own SAS units, right.
Is it the same in New Zealand?
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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #17 on: 29/01/2009 04:57:14 »
I don't really know much about the army, New Zealand has a small army, because no-body is going to attack us (at least that is what the government thinks), hee hee, mwahaaa   hahaaha 

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Offline yor_on

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Do white coloured objects reflect infrared radiation?
« Reply #18 on: 29/01/2009 04:59:56 »
Well, I've heard about some real dangerous Beavers on the loose.
Warn them...
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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #19 on: 29/01/2009 05:01:35 »
Don't worry, I'll take care of this!

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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #20 on: 29/01/2009 05:02:49 »
Look away Mr. yor_on! This is getting violent!

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Offline yor_on

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Do white coloured objects reflect infrared radiation?
« Reply #21 on: 29/01/2009 05:04:08 »
Mr chem, are you sure you're not 'connected'?
This is starting to look dangerous.
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Offline Chemistry4me

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« Reply #22 on: 29/01/2009 05:06:14 »
WAIT A MINUTE! There are no beavers in New Zealand!!!
I think you might have meant possums Mr.yor_on.
« Last Edit: 29/01/2009 05:09:37 by Chemistry4me »

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Offline yor_on

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Do white coloured objects reflect infrared radiation?
« Reply #23 on: 29/01/2009 05:11:50 »
Nope, gotta warn you, there are beavers loose everywhere!!!
And they are masters of deception.

One even succeeded to get into my laptop.
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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #24 on: 29/01/2009 05:14:45 »
Oh no! I must boost the security on my computer!

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Offline Chemistry4me

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« Reply #25 on: 29/01/2009 05:18:32 »
Damn it! It isn't working, the beaver got in!!!

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Offline yor_on

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« Reply #26 on: 29/01/2009 05:19:45 »
Don't worry, he turned out to be a friendly chap.
It's not like a virus or anything.

They are mostly brown and can weight up to several pounds I've heard.
But you better take down all trees and carry them into your chamber.

Otherwise they soon will be gone.
But you're used to that in New Zealand, right?
Didn't you have 'Ents' under there recently?

--------

http://en.wikipedia.org/wiki/Ent

« Last Edit: 29/01/2009 05:27:04 by yor_on »
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Offline yor_on

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« Reply #27 on: 29/01/2009 05:24:26 »
You know.

"New Zealand, Home of the Middle-earthers."
Well sort of?

http://www.newzealand.com/travel/about-nz/culture/lotr/lotr-02.cfm

We too have a slogan.
"Sweden the home of the middling nutters"
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Offline Chemistry4me

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« Reply #28 on: 29/01/2009 05:25:14 »
Oh please Mr. yor_on, you've been reading way too much Tolkien!

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Offline yor_on

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« Reply #29 on: 29/01/2009 05:38:50 »
No way, to little I would say.
Mr Chem, its been a pleasure exchanging information with you.
And as we, each one, seems to have a beaver:)

Well, not really.
You know...

Figuratively speaking?
Mine is screaming btw.

To 'shut the *** up' and stop laughing.
We better finish this chapter as fast as humanly possible.

There are nothing so worrisome as to be worried by the presence of an avenging angel.
As this one is angling for my life, it seems.

So Mr Chem I will leave you with this old Chinese saying.
Apropos beavers.

'One bird in the hand is worth two in the bush'

"BOMB DISPOSAL EXPERT. If you see me running, try to keep up."

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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #30 on: 29/01/2009 05:40:17 »
Are you going to sleep?

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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #31 on: 29/01/2009 05:45:19 »
Okay, enough said, you must have fallen asleep.

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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #32 on: 29/01/2009 06:43:48 »
What are you still doing here? Go to sleep!

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Offline Bored chemist

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Do white coloured objects reflect infrared radiation?
« Reply #33 on: 29/01/2009 06:53:38 »
Morning all.
The answer to the question is  "generally yes".
Please disregard all previous signatures.

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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #34 on: 29/01/2009 06:55:58 »
Why didn't you just say so earlier?   [:D][:D] I was stuck with Mr. yor_on for two hours!! [;D] [;D] [;D]

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Offline Glyph

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Do white coloured objects reflect infrared radiation?
« Reply #35 on: 29/01/2009 07:27:30 »
The reflectance of a surface is not necessarily the same for all wavelengths of electromagnetic radiation, e.g. vegetation strongly reflects IR so appears much whiter in an IR monochrome image than in a regular monochrome (black & white) photo ...

[attachment=6597]


                       regular monochrome                                                      Infrared monochrome

http://en.wikipedia.org/wiki/File:Rudin-house.jpg

http://en.wikipedia.org/wiki/Infrared_photography
« Last Edit: 29/01/2009 07:39:28 by Glyph »

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Offline Chemistry4me

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« Reply #36 on: 29/01/2009 07:43:04 »
Hey, that is really neat Glyph, thank you! [:)]

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Offline Bored chemist

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Do white coloured objects reflect infrared radiation?
« Reply #37 on: 29/01/2009 20:29:49 »
Why didn't you just say so earlier?   [:D][:D] I was stuck with Mr. yor_on for two hours!! [;D] [;D] [;D]
Because it was some stupidly early hour of the morning.
BTW, Glyph, thanks for the image but I think that saying "The reflectance of a surface is not necessarily the same for all wavelengths of electromagnetic radiation" is only informative to someone with no colour vision.
Incidentally, at some wavelength the white stuff will absorb IR but, for near IR, white things are likely to reflect IR just as they reflect visible light. There's nothing magical about the cutoff between one form of radiation and the other- it just happens to be the way our eyes work.
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Offline lightarrow

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Do white coloured objects reflect infrared radiation?
« Reply #38 on: 29/01/2009 20:59:31 »
BTW, Glyph, thanks for the image but I think that saying "The reflectance of a surface is not necessarily the same for all wavelengths of electromagnetic radiation" is only informative to someone with no colour vision.
He was not very precise, he should have written "The reflectance of a given surface is not necessarily the same for all wavelengths of electromagnetic radiation, even if, for that surface, it's the same for all the wavelenghts in the visible range".

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Offline yor_on

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« Reply #39 on: 30/01/2009 11:23:22 »
Didn't think of that:)
But it's true that IR and 'near IR' is just near, not the same.
But what color would then be the most reflective?
off white:)

----

I've also learnt that dark blue is one, or the one, of the most 'difficult' colours for us to see when dusk is 'falling in'.
Any views on that?
« Last Edit: 30/01/2009 11:28:35 by yor_on »
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Offline Chemistry4me

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Do white coloured objects reflect infrared radiation?
« Reply #40 on: 30/01/2009 11:24:49 »

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Offline Chemistry4me

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« Reply #41 on: 30/01/2009 11:29:27 »
I've also learnt that dark blue is one, or the one, of the most 'difficult' colours for us to see when dusk is 'falling in'.
Any views on that?
Nope!

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Offline lightarrow

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Do white coloured objects reflect infrared radiation?
« Reply #42 on: 30/01/2009 18:56:19 »
Didn't think of that:)
But it's true that IR and 'near IR' is just near, not the same.
But what color would then be the most reflective?
off white:)
[???]
Quote
I've also learnt that dark blue is one, or the one, of the most 'difficult' colours for us to see when dusk is 'falling in'.
Any views on that?
The sensitivity of retina for colours at the tails of the sensitivity curve is lower; the peak is on the green-yellow, so others colours are perceived worse, so when the light is dimmer, you can't perceive reds, oranges and blues anylonger, while you still perceive green-yellow. However the effect is complicated because when cones stop functioning, the rods are left functioning and they have another visibility curve; their peak is on the blue-green; see also "Purkinje effect":
http://en.wikipedia.org/wiki/Purkinje_effect

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Offline Glyph

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Do white coloured objects reflect infrared radiation?
« Reply #43 on: 30/01/2009 19:33:00 »
Here is a better example of what I meant ...

[attachment=6618]

http://www.usatoday.com/news/world/2008-08-27-3508714940_x.htm

Un-inked areas of the scrolls which appear almost black in visible light are much brighter in IR.
The reflectance of visible light and the reflectance of IR from a surface do not necessarily correlate.
« Last Edit: 30/01/2009 19:36:07 by Glyph »

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Do white coloured objects reflect infrared radiation?
« Reply #44 on: 31/01/2009 00:16:54 »
I had an unexpected direct experience of this many years ago when I was working on an idea for improving infra red fire detectors which could be subject to gradual degradation due to their windows getting dirty or the visibliity of the flickering heat of a fire being obscured by smoke.  I was using a broad band flash tube to generate a bright infra red flash to test them in a large fire testing chamber which was very black sooty dirty and dark because of all the things that had been built in it and set alight to test various aspects of fire safery  detectors and extinguishants.  The results were not what we expected until we realised that at the infra red frequences we were using the whole room looked like it was painted brilliant white!
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Offline yor_on

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« Reply #45 on: 31/01/2009 05:30:23 »
http://www.echeng.com/photo/infrared/tutorial/

It was this I meant with near Ir as compared to IR Lightarrow:)
What you wrote about dark blue was interesting.
I've always wondered if that was correct, but those teaching it was quite serious.

So it might work at dusk then, but not when getting real dark?
« Last Edit: 31/01/2009 05:32:43 by yor_on »
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Offline Chemistry4me

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« Reply #46 on: 31/01/2009 05:33:13 »
Hmmm... so you do know your waves.

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Offline swansont

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« Reply #47 on: 04/02/2009 11:10:28 »

I've also learnt that dark blue is one, or the one, of the most 'difficult' colours for us to see when dusk is 'falling in'.
Any views on that?

Blue, in general, is difficult to see because your eye isn't as efficient at the extreme wavelengths.  But when your eyes become dark-adjusted, it's easier to see blue (scotopic vs photopic vision)

http://hyperphysics.phy-astr.gsu.edu/Hbase/vision/bright.html

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Offline lightarrow

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« Reply #48 on: 04/02/2009 13:01:58 »
Blue, in general, is difficult to see because your eye isn't as efficient at the extreme wavelengths.  But when your eyes become dark-adjusted, it's easier to see blue (scotopic vs photopic vision)

http://hyperphysics.phy-astr.gsu.edu/Hbase/vision/bright.html

Yes, that is exactly the reason of the Purkinje effect I was talking about in my previous post.