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Author Topic: OMG LoL @ Metamerism  (Read 1813 times)

32BT

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OMG LoL @ Metamerism
« on: July 06, 2019, 03:35:59 pm »

I swear that orb looked exactly like the sky. Had the same kind of luminance, same kind of gray. In fact, I thought for a moment the sky was reflected in the orb. Couldn't quite tell whether the lamp was turned on, or whether the sun was merely reflecting inside. Thought it could make a funny picture, almost like a lens inversion in the sky.

Took out the little point & shoot, looked at the lcd, started laughing out loud. Had to take the picture anyway to show you lot.

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32BT

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Re: OMG LoL @ Metamerism
« Reply #1 on: July 06, 2019, 03:48:11 pm »

What I more or less saw visually
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digitaldog

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Re: OMG LoL @ Metamerism
« Reply #2 on: July 06, 2019, 03:52:00 pm »

I'm not understanding the title: Metamerism.
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32BT

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Re: OMG LoL @ Metamerism
« Reply #3 on: July 06, 2019, 05:00:56 pm »

I'm not understanding the title: Metamerism.

Apparently my eye/brain combo decided that the daylight spectrum and whatever horrible spectrum came off the lamp was visually identical.
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digitaldog

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Re: OMG LoL @ Metamerism
« Reply #4 on: July 06, 2019, 05:37:19 pm »

Okay, that kinda makes sense now. 😃
Camera metameric failure?
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Eric Myrvaagnes

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Re: OMG LoL @ Metamerism
« Reply #5 on: July 06, 2019, 10:46:13 pm »

If it were me, I could blame it on my genetic ocular metamerism (a.k.a. color-vision deficiency).

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32BT

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Re: OMG LoL @ Metamerism
« Reply #6 on: July 07, 2019, 03:53:35 am »

Okay, that kinda makes sense now. 😃
Camera metameric failure?

Apparently, but the question is: how? Could it be the IR filter? (i.e. I perceive deeper into the red spectrum than the camera and therefor I perceive more red in the lamp?) Or simply spiky spectrum from the lamp that my eyes equalise? (The lamp seemed to be some kind of older energy-savings type, considering it had a long "warm-up" time.)
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32BT

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Re: OMG LoL @ Metamerism
« Reply #7 on: July 07, 2019, 03:54:48 am »

If it were me, I could blame it on my genetic ocular metamerism (a.k.a. color-vision deficiency).

Ah yes, but you do see red-green distinction, no? So you likely see the difference in the above images?
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MauriceRR

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Re: OMG LoL @ Metamerism
« Reply #8 on: July 07, 2019, 04:05:19 am »

It can also be amplified by the color lut chosen (is it quite thé same effect in Adobe /capture1, rawrherapee ?
Which camera is it ? Smartphone or dslr ?
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Eric Myrvaagnes

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Re: OMG LoL @ Metamerism
« Reply #9 on: July 07, 2019, 09:05:03 am »

Ah yes, but you do see red-green distinction, no? So you likely see the difference in the above images?
Yes, to both.
I have no trouble with traffic lights: "Red" lights look red, and "Green" lights look sort of off-white.
Your "gray" photo looks consistently grayish to me, but the light in the "as I saw it" looks pale yellowish while the background looks gray.
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digitaldog

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Re: OMG LoL @ Metamerism
« Reply #10 on: July 07, 2019, 12:50:21 pm »

If it were me, I could blame it on my genetic ocular metamerism (a.k.a. color-vision deficiency).
If that were actually metamerism, it wouldn’t be a deficiency. Metamerism is a good and useful attribute. Metameric failure isn't.  :'(
When samples with different spectra compared to each other with a given set of viewing conditions actually produce a match, the result is Metamerism and that's not a deficiency in my book.


A "meterameric pair of color patches" (two samples) means that they appear to match under a given illuminant. However, they may not appear to match under another illuminant and thus that isn't metamerism. If it was not for metamerism, none of our three color reproduction systems would work very well. Because of metamerism we are able, using only three colors, to cause the human vision system to perceive a match between this tristimulus reproduction system and full spectral pigment. As for the camera below (or above), and why it may suffer metameric failure, there may be many reasons. Does the camera that meets the Luther-Ives condition? If not, this means that cameras can exhibit significant metameric failure compared to humans.
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Eric Myrvaagnes

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Re: OMG LoL @ Metamerism
« Reply #11 on: July 07, 2019, 04:15:57 pm »

I agree that my condition is not Metamerism, but it is a real deficiency.
As a teenager I had a necktie that I thought was gray (under any illumination) until someone without my color issue told me that it was "blue-green" or "cyan."
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digitaldog

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Re: OMG LoL @ Metamerism
« Reply #12 on: July 07, 2019, 04:18:46 pm »

My dad was red/green colorblind or so he reported. Fortunately he didn't pass this onto any of his kids.
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Eric Myrvaagnes

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Re: OMG LoL @ Metamerism
« Reply #13 on: July 07, 2019, 06:56:34 pm »

My dad was red/green colorblind or so he reported. Fortunately he didn't pass this onto any of his kids.
It is generally passed on through the daughter (she won't be color-blind, only a carrier), and then half of her male offspring will be C-B.
It worked out just like that for my family: My mother's father was R_G color-blind, and my brother was not, but I am.

Of course, it was the color-blind one that got into photography. It was no problem as long as I stuck to black and white only. But then color became so easy (or so I imagined) in the digital era...   ;)
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Mick Sang

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Re: OMG LoL @ Metamerism
« Reply #14 on: July 07, 2019, 10:46:21 pm »

Quote
Apparently, but the question is: how? Could it be the IR filter?

The mind discounts the illuminant (colour constancy) while cameras do not. It seems to me that apparently, either the globe or the bulb inside it, if it was on or warming up, emitted or reflected a spectrum which the camera saw and the eye discounted.
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32BT

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Re: OMG LoL @ Metamerism
« Reply #15 on: July 08, 2019, 07:15:27 am »

The mind discounts the illuminant (colour constancy) while cameras do not. It seems to me that apparently, either the globe or the bulb inside it, if it was on or warming up, emitted or reflected a spectrum which the camera saw and the eye discounted.

The mind doesn't do selective adaptation. In addition, the "extra" perceived information by the camera seems to be in the green region, which is exactly where you'd expect human vision to have an advantage. Imo, there are two possibilities:
1. the camera's green response is triggered by spikes in the green region, spikes that my vision equalises.
2. the camera's ability to detect the full red response is limited by for example the IR filter

Polarisation in both the source, as well as the camera (lenscoatings?) may exacerbate the problem.

From previous experience, nr 2 is the core of a lot of camera issues. As an example: the inability of an autofocus system to work properly under old energy-savings lighting.



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Jack Hogan

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Re: OMG LoL @ Metamerism
« Reply #16 on: July 09, 2019, 04:01:37 pm »

I swear that orb looked exactly like the sky. Had the same kind of luminance, same kind of gray. In fact, I thought for a moment the sky was reflected in the orb. Couldn't quite tell whether the lamp was turned on, or whether the sun was merely reflecting inside. Thought it could make a funny picture, almost like a lens inversion in the sky.

Took out the little point & shoot, looked at the lcd, started laughing out loud. Had to take the picture anyway to show you lot.

Good one.  Did 'Gray World' white balance contribute?  It'd be interesting to have a gray card in there.
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