Magenta/Purple Trees Gray Card Test

[rabanito]

FWIW:

Following an idea by Eric:

My guess (as a color-deficient "Expert") is that the green foliage shifts the color balance in the "as shot" version.
Taking an initial shot with a gray card would give you something to use for setting color balance with the eye-dropper in LightRoom or PS.

I made a series of photographs early evening in the forest including a gray card
The camera was set at WB: Automatic This set was taken w/ ISO 1000. Images taken with other ISO values look similar

The WB was adjusted in LR:
1. As Shot
2. Auto
3.Custom (eye dropper on the gray card)

The RGB and the Lab values were (eyedropper in PS)

1. 183 194 214  ///   +81  -7  -12
2. 185 185 214  ///   +80 +2  -14
3. 194 194 194  ///   +82   0     0


No magenta cast as far as I can judge
Please correct me if there are mistakes in the procedure or interpretation

[degrub]

cyan
magenta
yellow
casts
on my calibrated PA241W and my eyes 

last one might be from my slight cataracts.

[rabanito]

cyan
magenta
yellow
casts
on my calibrated PA241W and my eyes 

last one might be from my slight cataracts.

Hmmmm...
Maybe I'm assuming something wrong?

I measure the cast on the grey card
In the first two (as shot and auto) there is a slight bluish cast with a touch of yellow
In the third there is (as expected) no cast at all (RGB 3x194, Lab 82,0,0)

And these values are independent from the display.
Now  if I increase saturation on any of those three to the maximum, I still see no magenta

The foliage is IMHO irrelevant except for generating a cast or misleading my camera to to make a wrong correction (because of the so much green overshooting the magenta, something that is NOT happening)

Mystery...

[Rob C]

On the iPad, the grey in the first looks a tiny bit blue/grey; on the second shot the card looks grey, whereas the third one looks yellowish grey to me.

Also, the greys don't look to me to be of equal strength.

This thing about cataracts raises an interesting point, because I'm waiting to have both of mine removed in about four months, and I read somewhere that cataracts give a yellowish tinge... can't say I have noticed that, though, but then being a gradual deterioration, would one notice?

Rob

[degrub]

likely will after the surgery since the brain will not have any adaption. brightness will kick up a stop as well.

[Eric Myrvaagnes]

My eyes have been color-deficient both before and after cataract operations. To my eyes, the three gray cards all look slightly different, but I can't name whatever is different about them.

[Martin Kristiansen]

I had double cataract surgery years ago. Simple and painless procedure. Did right eye then a few weeks later the left. Don’t recall how long the gap between was. About two weeks perhaps. When the one eye had been done I could see a shift in colour between the two eyes. If I opened just the right eye then swapped to the left I noticed a shift to yellow. I don’t believe it matters once both are done. Our eyes are constantly auto white balancing. You don’t really see how yellow tungsten lighting is or how blue mid day sunlight can be. It gets normalised by our minds. Surely that is the case for colour shifts with cataracts as well. What does change is clarity, contrast, night vision and the ability to see into oncoming lights at night when driving.

Regarding this image of the tree. We seem to have a tendency to rely on science too much. It’s not how does it look but how do we want to show it. Try remember how it looked to you when you saw it. What attracted you to make the image, then adjust to match that as a starting point. If you think the colour looks weird then change it. All this matching to what is actually there is futile in my opinion. Most of our vision is in our minds, not our eyes.

[Rob C]

I had double cataract surgery years ago. Simple and painless procedure. Did right eye then a few weeks later the left. Don’t recall how long the gap between was. About two weeks perhaps. When the one eye had been done I could see a shift in colour between the two eyes. If I opened just the right eye then swapped to the left I noticed a shift to yellow. I don’t believe it matters once both are done. Our eyes are constantly auto white balancing. You don’t really see how yellow tungsten lighting is or how blue mid day sunlight can be. It gets normalised by our minds. Surely that is the case for colour shifts with cataracts as well. What does change is clarity, contrast, night vision and the ability to see into oncoming lights at night when driving.

Regarding this image of the tree. We seem to have a tendency to rely on science too much. It’s not how does it look but how do we want to show it. Try remember how it looked to you when you saw it. What attracted you to make the image, then adjust to match that as a starting point. If you think the colour looks weird then change it. All this matching to what is actually there is futile in my opinion. Most of our vision is in our minds, not our eyes.

Thanks for the heads up on the cataract prospects. Two things happened when I got my present car, my first and only diesel: it ruined my confidence at overtaking below about 65kph, but the high torque made it easy on long and fast motorway hills where it leaves similar petrol cars behind, and the onset of cataracts began to nibble away at confidence too, because I just wasn't going to risk it when I wasn't sure I had the distance both to build up speed and to see well enough in combination with everything else.

Regarding the colours in photographs: yes, for one's own work, please oneself, but for other people...

Rob

[rabanito]

I had double cataract surgery years ago. Simple and painless procedure. Did right eye then a few weeks later the left. Don’t recall how long the gap between was. About two weeks perhaps. When the one eye had been done I could see a shift in colour between the two eyes. If I opened just the right eye then swapped to the left I noticed a shift to yellow. I don’t believe it matters once both are done. Our eyes are constantly auto white balancing. You don’t really see how yellow tungsten lighting is or how blue mid day sunlight can be. It gets normalised by our minds. Surely that is the case for colour shifts with cataracts as well. What does change is clarity, contrast, night vision and the ability to see into oncoming lights at night when driving.

Regarding this image of the tree. We seem to have a tendency to rely on science too much. It’s not how does it look but how do we want to show it. Try remember how it looked to you when you saw it. What attracted you to make the image, then adjust to match that as a starting point. If you think the colour looks weird then change it. All this matching to what is actually there is futile in my opinion. Most of our vision is in our minds, not our eyes.

As for catraracts, we're not alone

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4408507/
On Monet

I agree with you on what we want to show. I manipulate my images always. I don't expect a reproduction of how it "really" was but my own interpretation

OTOH, I was curious about why this particular phenomenon was happening. Something w my camera, w my calibration, black magic...

Example:
With panchromatic film, if you put a strong red filter on the lens, all greens will be darkened.
Well not all. I am told the leaves, full of chlorophyll, reflect infrared and on panchromatic film (sensitive to IR too) green foliage will appear lighter instead of darker

Something similar in this case.
As a newbie in digital and color photography I am surprised by things that happen "against the law" and ask myself what could be the matter
1.Out of curiosity
2.To make the right corrections and not doing something that "works just for that picture". That's where "science"  and adequate tests can help

[rabanito]

BTW thanks to everybody for your opinions! 

[Slobodan Blagojevic]

One thing to take into account: cedar trees are magenta/purple-ish in nature:

[rabanito]

One thing to take into account: cedar trees are magenta/purple-ish in nature:

Occam's razor.

https://c8.alamy.com/comp/BGBPWJ/moss-covered-base-of-a-large-western-redcedar-tree-western-red-cedar-BGBPWJ.jpg

Indeed!