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Author Topic: Colour of light matters  (Read 24150 times)

Stas Wilf

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Re: Colour of light matters
« Reply #120 on: July 11, 2013, 07:17:39 PM »

The problem, from my point of view, is providing dual-illuminant profile as a simple solution to the problem that has no simple solutions.
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digitaldog

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Re: Colour of light matters
« Reply #121 on: July 11, 2013, 07:21:06 PM »

The problem, from my point of view, is providing dual-illuminant profile as a simple solution to the problem that has no simple solutions.

One doesn't have to use dual illuminant profiles but further, where's the actual problem? Is it a problem that is rare or very common and if the later, where are all the complaints?
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Andrew Rodney
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Stas Wilf

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Re: Colour of light matters
« Reply #122 on: July 11, 2013, 07:35:05 PM »

One doesn't have to use them. But most people use them, and most people do not know it.
And those who do know seem to think that using dual-illuminant profile and setting "correct" white balance is enough to get a decent rendition of colors.
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Iliah

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Re: Colour of light matters
« Reply #123 on: July 11, 2013, 07:38:58 PM »

> You just assume and speculate

No, I see. You may need EXIF.
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digitaldog

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Re: Colour of light matters
« Reply #124 on: July 11, 2013, 07:44:40 PM »

> You just assume and speculate
No, I see. You may need EXIF.

Wrong again! I did see the EXIF data, it doesn't let you off the hook one bit. As usual, you fail to read what I've written: You can't have any idea about the camera original, raw or JPEG without having the camera original.
You don't have the camera original. You have zero idea what was done to the image in terms of processing. You assume as usual. And you continue to keep moving down this path to digress from your original silly idea about this ACR "problem" you can neither illustrate or identify.
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Andrew Rodney
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Iliah

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Re: Colour of light matters
« Reply #125 on: July 11, 2013, 07:47:42 PM »

Yes as defined by lining up the Lab numbers to the CCchart pictured below which is colormetrically accurate by the numbers as well as visually accurate. That's what I mean when I make the connection when a machine's numbers actually match up to what I see which is rare because my eyes keep adapting to every scene I photograph which are not CC charts.

Did that make your day?

sRGB rendition of CC24 can't be colorimetrically accurate as it exceeds sRGB gamut. The image has no value without the actual raw and repeatable steps.
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Iliah

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Re: Colour of light matters
« Reply #126 on: July 11, 2013, 08:02:33 PM »

Wrong again! I did see the EXIF data, it doesn't let you off the hook one bit. As usual, you fail to read what I've written: You can't have any idea about the camera original, raw or JPEG without having the camera original.
You don't have the camera original. You have zero idea what was done to the image in terms of processing. You assume as usual. And you continue to keep moving down this path to digress from your original silly idea about this ACR "problem" you can neither illustrate or identify.

Good that you saw it. Now is it Tim's image? Could it be shoot in raw? Is there any burnt red on the palm? Was this image to demonstrate any accuracy, even an accurate representation of the painting?

Sometimes one can't judge exposures without looking at original, sometimes one can.

Your talk in regards to this image here http://www.luminous-landscape.com/forum/index.php?topic=80130.msg647205#msg647205 saying
"You have Tim's raw? If not, you once again made a big assumption and passed it off as a fact. You could have no way to know anything about the exposure. It could have a stop or more latitude. Hence my question to you (From what image, the one downloaded from the web page?) which you conveniently haven't answered, like most of the questions presented to you. Again, you have the raw? You're making points about exposure and development based on Tim's post to the web? Is this yet another digression (like the one on the Fraser piece) to ignore your lack of any facts presented here in terms of this invisible ACR problem?"
is obviously showing lack of attention. It is as close to original as it can be because original is most likely OOC JPEG.
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digitaldog

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Re: Colour of light matters
« Reply #127 on: July 11, 2013, 08:10:35 PM »

Good that you saw it. Now is it Tim's image?
Why not ask Vladimirovich who wrote first:
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Tim Lookingbill has them because he (Tim) was claiming that it (digital capture) was "color metrically accurate"... shall be so (to accurately capture "pleasing" painting)
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Could it be shoot in raw?
Nope, but that's pointless as I said later as you can't speak to the processing since you do NOT have the camera original.
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Is there any burnt red on the palm?

Not that I see (not that it matters).
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Was this image to demonstrate any accuracy, even an accurate representation of the painting?
I don't know what the point of the image is. I know you can't make any points about how it was captured or processed and I know this is yet another unnecessary digression you've continued to discuss to presumably ignore the bigger issue, your idea that ACR has a problem you continue to fail to address!
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Sometimes one can't judge exposures without looking at original, sometimes one can.
And sometimes pigs can fly, so what?
At what point will you address the actual issue: this invisible problem with the ACR engine?
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Andrew Rodney
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bjanes

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Re: Colour of light matters
« Reply #128 on: July 11, 2013, 09:10:10 PM »

Yes as defined by lining up the Lab numbers to the CCchart pictured below which is colormetrically accurate by the numbers as well as visually accurate. That's what I mean when I make the connection when a machine's numbers actually match up to what I see which is rare because my eyes keep adapting to every scene I photograph which are not CC charts.

Did that make your day?

That's a pretty good calibration, but hardly colorimetrically accurate. The image is in sRGB, and as Iliah has pointed out, patch 18 (cyan) is out of the sRGB gamut. According to Bruce Lindbloom the sRGB values for that patch are -49, 135, 166 and you have 0, 140, 175. Shown below are analyses of your rendering according to Imatest. What you do not seem to understand is that the sensors of our cameras do not meet the Luther-Ives criteria and metameric error occurs. You can optimize the matrix for some colors under a given illuminant (in this case for the color checker), but other colors not shown in the chart (as purple with flowers) will be off. What Iliah showed in his original post is that metameric error with tungsten illumination can be reduced with an 80a filter and this can be documented by DeltaEs. For art reproduction and scientific photography where accurate color is the goal, this could be useful. His useful observation was sidetracked by your and others' rants about accurate and pleasing color. Kodachrome strove for accurate color but many photographers preferred Velvia for landscapes and Astia for portraits. Generally, most photographers like increased saturation but hue shifts are less welcome. For artistic rendition, pleasing color may not even be desirable.

Bill
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xpatUSA

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Re: Colour of light matters
« Reply #129 on: July 11, 2013, 09:23:49 PM »

sRGB rendition of CC24 can't be colorimetrically accurate as it exceeds sRGB gamut.
Interesting. Could you please post the reference for that statement and tell us what "it" is referring to?

Please don't side-step the question . . .

All the patches on my mini-card are in-gamut except for cyan. As are the patches on Norman Koren's sRGB simulation . . .



[edit] I see Bill posted similarly to the above while I was typing . . . [/edit]
« Last Edit: July 11, 2013, 09:25:37 PM by xpatUSA »
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Ted

digitaldog

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Re: Colour of light matters
« Reply #130 on: July 11, 2013, 09:52:38 PM »

All the patches on my mini-card are in-gamut except for cyan. As are the patches on Norman Koren's sRGB simulation . . .

I also see this (only Cyan OOG in sRGB) but before we go farther, we need Tim to let us know if he's referring to sRGB or that's just what he used to post his image to the web. It's possible his testing was done in a larger color space whereby Cyan would fall into gamut and as expected, sRGB was posted for a web page.
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Andrew Rodney
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bjanes

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Re: Colour of light matters
« Reply #131 on: July 11, 2013, 10:07:31 PM »

I also see this (only Cyan OOG in sRGB) but before we go farther, we need Tim to let us know if he's referring to sRGB or that's just what he used to post his image to the web. It's possible his testing was done in a larger color space whereby Cyan would fall into gamut and as expected, sRGB was posted for a web page.

Maybe so, but in any event the orange is in sRGB gamut and has a delta E even larger than the cyan. The image is not a perfectly colorimetric rendering as Tim claimed. He does not seem to appreciate metameric error.

Bill
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Tim Lookingbill

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Re: Colour of light matters
« Reply #132 on: July 11, 2013, 11:34:30 PM »

I also see this (only Cyan OOG in sRGB) but before we go farther, we need Tim to let us know if he's referring to sRGB or that's just what he used to post his image to the web. It's possible his testing was done in a larger color space whereby Cyan would fall into gamut and as expected, sRGB was posted for a web page.

My posting the CCchart got totally taken out of context of my original point and now is being scrutinized as some kind of empirical scientific evidence of a representation of split hair accuracy errors in relation to the numbers and how they appear in sRGB space.

According to Eric Chan, the actual CCchart Lab numbers can be off by as much as 5 points in either channel before you can see a substantial color difference or for it to have a noticeable effect on a wide range of images applying the DNG profile that created the slightly off CCchart numbers. I meant it as a loose guide to define what I consider colorimetric accuracyfrom a visual perspective more so than by the numbers in defining ACR defaults for my camera. And if you want to argue that go talk to Eric.

And of course the "painting held in hand in front of the actual scene shot with what I'm guessing is a P&S camera" I linked to was also taken out of context of the point I was trying to make which was to illustrate optical tricks implemented in painting techniques to imbue a 3D effect to a 2D image that the ACR color engine employs only not so pronounced. But I see nobody picked up on that and I doubt any of you ever will so I'm done here cuz' I'm not going to repeat myself here anymore. You either get it or you don't.

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Vladimirovich

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Re: Colour of light matters
« Reply #133 on: July 11, 2013, 11:50:23 PM »

to imbue a 3D effect to a 2D image that the ACR color engine employs only not so pronounced. But I see nobody picked up on that
no takers for snake oil... "ACR color engine" is as capable to produce (in certain hands) dull images as quite opposite ones and so do other raw converters.
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Tim Lookingbill

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Re: Colour of light matters
« Reply #134 on: July 12, 2013, 12:08:06 AM »

no takers for snake oil... "ACR color engine" is as capable to produce (in certain hands) dull images as quite opposite ones and so do other raw converters.

Show us an example.
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Iliah

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Re: Colour of light matters
« Reply #135 on: July 12, 2013, 12:27:33 AM »

> My posting the CCchart got totally taken out of context

Where is the raw?
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Iliah

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Re: Colour of light matters
« Reply #136 on: July 12, 2013, 12:39:21 AM »

Bill, I would start my analysis with checking light uniformity and geometrical flatness of the card.
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Iliah

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Re: Colour of light matters
« Reply #137 on: July 12, 2013, 01:11:34 AM »

> He does not seem to appreciate metameric error.

It is not just metameric error what I encounted because using LUT profiles one is getting much smaller deltaE.
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Iliah

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Re: Colour of light matters
« Reply #138 on: July 12, 2013, 02:26:05 AM »

Your assumption that for this image raw is needed to judge the exposure is wrong, isn't it?

> And sometimes pigs can fly, so what?
Really? In raw?

> Not that I see
Well, you just said it.

> At what point will you address the actual issue: this invisible problem with the ACR engine?
All in good time. But it will not help as the way ACR treats images won't change.
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Schewe

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Re: Colour of light matters
« Reply #139 on: July 12, 2013, 03:58:08 AM »

But it will not help as the way ACR treats images won't change.

Bullshit bud...while it's true that Thomas won't change things based on crackpot, half-baked ideas, Thomas is certainly willing to make major and substantial changes if somebody can prove to him he should...PV 2003 was the original pre DNG profile process version...which didn't change till PV 2010 which incorporated a lot of changes.

Then in PV 2012, a complete wholesale change to the processing was added. I would count this as proof positive that the ACR/LR engineers WILL make changes, sometimes massive, if somebody can prove what they are doing can be improved. Apparently, you've been unsuccessful in proving that to Thomas. I wonder why? Could it be your approach? Or could it be that Thomas doesn't think too much about your rants? In my experience, Thomas is almost always right, except when you can prove him wrong and then he's willing to turn on a dime because Thomas really does want to do the right thing...

Thomas has a track record...he co-authored Photoshop, he was the founding engineer on ACR and worked closely with Mark Hamburg in developing Lightroom...these guys have a proven track record and in effect, created this whole friggin' industry...you gotta have some stones to want to go up against the likes of those guys. So far, I don't think you match up. I'll back Thomas over you.

BTW, as to your OP, the results should have been self-evident...of course a capture under tungsten with LB filters would produce a better result than trying to WB a tungsten shot. DOH...so, yes, you original question has been proven. All the rest has been mental masturbation...something you are good at.
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