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Author Topic: Colour of light matters  (Read 8068 times)
Iliah
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« Reply #140 on: July 12, 2013, 03:07:33 AM »
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> 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

We will see.

> 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.

And who was that? Themselves?
The change of the main idea of interpolating between 2 profiles - I do not see it coming before 2018.

> Apparently, you've been unsuccessful in proving that to Thomas

> BTW, as to your OP, the results should have been self-evident

For me - yes. For many photographers attempting to profile using HomeDepot halogens - apparently no.

> All the rest has been mental masturbation...something you are good at.

You realize of course how thick is my skin, yet you waste time trying to get under it Smiley
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Schewe
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« Reply #141 on: July 12, 2013, 03:23:02 AM »
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You realize of course how thick is my skin, yet you waste time trying to get under it Smiley

No, I'm not trying to get under your skin...I just want other readers to be able to grok what you are doing. Some people don't know you and your tactics...I do. Next?

BTW, Sorry I didn't respond to your assalt on Bruce's article...my wife and daughter decided today would be a good day to see The Lone Ranger...pretty good movie.

As to what Bruce was a bit foggy on was the fact that he presumed that linear exposure had some sort of relationship with levels in a 12-bit linear capture vs actual photons captured. But remember, Bruce wrote this in 2004...very early on in the whole digital capture business and was trying to explain linear vs gamma encoded color spaces. I'm pretty sure Bruce would have something different to say today. Sadly, he's not here to explain himself...personally, I'm inclined to let what Bruce wrote stand on it's own terms. Where possible, I've tried to extend and expand on what I think Bruce thought. But I'm not Bruce...nor are you–not even close.
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Iliah
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« Reply #142 on: July 12, 2013, 03:39:23 AM »
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> I just want other readers to be able to grok what you are doing

They need your help? LOL

> Sorry I didn't respond to your assalt on Bruce's article

It was not an assault by any means and any standards. Knowing me as you claim you should have known better. Maybe you just don't know me Smiley

Since the article is on-line, and normal user knows to set PS colour settings to ask when opening on missing profiles, a comment not to make the article look wrong would help. Certainly a technical inconsistency with the number of separating lines on gradients for linear and gamma-corrected distributions should be taken care of too.
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Schewe
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« Reply #143 on: July 12, 2013, 03:48:27 AM »
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It was not an assault by any means and any standards.

Yes it was...your pointing to Bruce's writing came out of left field and had nothing to do with you OP...so, you agree that doing a CT correction in a digital capture is useful for better color accuracy? Regardless of the raw processing engine being used? I just want LuLa members to get something positive from all this verbal diarrhea...you know, giving the members something to do to improve their output?
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Iliah
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« Reply #144 on: July 12, 2013, 04:01:52 AM »
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> Yes it was...your pointing to Bruce's writing came out of left field

It is just a simple demonstration that you guys are defending your mistakes and avoid making corrections even when the mistakes are plain obvious, even for the sake of the good memory of your late dear friend.

> you agree that doing a CT correction in a digital capture is useful for better color accuracy?

Funny you should say that. Since year 2000 I practice that, and posted many times on that topic. While "useless filters" comments are still flooding in 2013.
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Schewe
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« Reply #145 on: July 12, 2013, 04:07:14 AM »
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While "useless filters" comments are still flooding in 2013.

Care to point to any posts where I said doing proper color correction of the taking light source was "useless"? I seriously doubt you'll find any since I advocate optimal raw capture parameters where possible. Since sensors are generally optimized for daylight (do you disagree) and capture at less than the optimized light source will produce suboptimal results. Agreed?
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Schewe
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« Reply #146 on: July 12, 2013, 04:12:20 AM »
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It is just a simple demonstration that you guys are defending your mistakes and avoid making corrections even when the mistakes are plain obvious, even for the sake of the good memory of your late dear friend.

Careful bud...I don't take potshots at Bruce lightly. You want to rewrite what Bruce wrote in 2004 for 2013, go right ahead. But you better be real careful...what Bruce was trying to explain was the difference between film and digital captures...you got anything useful to add to that? Do so...Otherwise, shut up...get it? It would be useful if you had anything useful to add vs crap you want to use to distract.
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Iliah
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« Reply #147 on: July 12, 2013, 04:13:40 AM »
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> Care to point to any posts where I said doing proper color correction of the taking light source was "useless"?

I hope you did not; but maybe you can point to any your posts saying those are necessary? It would be certainly a useful reference for those who want to avoid problems.

> Since sensors are generally optimized for daylight (do you disagree)

Generally yes, but not all of them, for example D4 is optimized for a little different spectrum, starting from 5800 and up to about 3800, including HMI and other types of lights commonly found on arenas. Some Canon models also tailored for arenas better then others.

It is important also to realize that spikes in the spectrum are not very well corrected with filters, and camera sensors are generally optimized for continuous spectrums.
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Iliah
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« Reply #148 on: July 12, 2013, 04:16:44 AM »
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> You want to rewrite what Bruce wrote in 2004 for 2013

No. I think some comments and explanations are due. The article itself is very good and also has historical value. It should not be edited, maybe apart from that technical issue with separators. But even that I would think has its place in comments.

Now, the problem of raw vs. film is usually that people are not comparing apples to apples. From certain perspective raw is a latent positive image, and should be compared to latent film image which is also mostly linear.
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Schewe
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« Reply #149 on: July 12, 2013, 04:19:16 AM »
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It is important also to realize that spikes in the spectrum are not very well corrected with filters, and camera sensors are generally optimized for continuous spectrums.

Correct...obvious if somebody had half a clue about sensor response to various light sources...which you could have advocated in your OP.
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Iliah
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« Reply #150 on: July 12, 2013, 04:28:15 AM »
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Correct...obvious if somebody had half a clue about sensor response to various light sources...which you could have advocated in your OP.

Quite a lot of shots under office FL lights are taken using shutter speeds of 1/200, 1/100 (in USA with 60Hz mains freq.). Next folks wonder why they have very different WB and very different resulting colour rendition even after correcting WB. I guess a lot of explanations is needed. People tend to trust that "cameras know what they are doing"
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digitaldog
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« Reply #151 on: July 12, 2013, 08:26:16 AM »
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> At what point will you address the actual issue: this invisible problem with the ACR engine?
All in good time.

I do not see it coming before 2018.
Why not invite some of your friends here to help you out?

Tim, don't close the door behind you, I'm coming!
« Last Edit: July 12, 2013, 08:52:52 AM by digitaldog » Logged

Andrew Rodney
Author “Color Management for Photographers”
http://digitaldog.net/
xpatUSA
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« Reply #152 on: July 12, 2013, 11:16:00 AM »
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Some general responses to your general statements:

Quite a lot of shots under office FL lights are taken using shutter speeds of 1/200, 1/100 (in USA with 60Hz mains freq.).

I see that "office" FL lighting is expected to have range of 2:1 lux in USA? Your reference, please?

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Next folks wonder why they have very different WB and very different resulting colour rendition even after correcting WB.

Could you try to clarify the above rather confusing statement? Under what circumstance is "very different" WB obtained?

For example, my SD9 and SD10 Sigmas are usually set to sunlight. Whatever that is in deg K and tint, it is fixed and not "very different". In fact not different at all. Works for all the shots I take around here - no incandescent lighting anywhere. Any glaring color inaccuracies are fixed to my satisfaction in post - or the shot is sent to the trash.

Could you please quantify "very different resulting colour rendition" in concrete terms, e.g. delta-E's? After all, one man's meat is anothers poison; horses for courses; etc; etc.

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I guess a lot of explanations is needed

They're all out there on the Web. Go Google or Bing or Yahoo or Alta-Vista (remember that one?).

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<People> tend to trust that "cameras know what they are doing"

With tongue firmly in cheek, I'd say that readers of this forum are not instances of members of your set <People>.

Perhaps: Pedants tend to distrust anything that the camera does. I am one such  Wink
« Last Edit: July 12, 2013, 11:24:00 AM by xpatUSA » Logged

best regards,

Ted
Iliah
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« Reply #153 on: July 12, 2013, 11:21:50 AM »
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> I see that "office" FL lighting is expected to have range of 2:1 lux in USA?

Not what I said.

> Could you try to clarify this rather confusing statement?

If shutter speed is set incorrectly and the light is from FL lights powered at 60Hz consecutive shots have different WB and different colour rendition after correcting WB.

> It's all out there on the web

And lots of it is wrong.

> readers of this forum are not instances of members of your set "People"

Rule #6
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Iliah
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« Reply #154 on: July 12, 2013, 11:24:14 AM »
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> I do not see it coming before 2018.

Hehe
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xpatUSA
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« Reply #155 on: July 12, 2013, 11:40:17 AM »
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>I see that "office" FL lighting is expected to have range of 2:1 lux in USA?

Not what I said.

My apologies. You said 'shutter speeds of 1/200, 1/100'. Did that imply a ratio of possible office illuminance or something else? Obviously I did not understand the generalization. Please clarify.

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> Could you try to clarify this rather confusing statement?

If shutter speed is set incorrectly and the light is from FL lights powered at 60Hz consecutive shots have different WB and different colour rendition after correcting WB.

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> It's all out there on the web

And lots of it is wrong.

I could be glib and say "And lots of it is right" but does it not go without saying that cognoscenti such as ourselves will make the right judgement?

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> readers of this forum are not instances of members of your set "People"

Rule #6

Too terse for me, I have no idea what that means.

You might make more headway in persuading this forum that (effectively) what comes out of the camera is not what went in if you would use full sentences, give credible references, post illustrative images and refrain from using phrases like "mental masturbation" (even if provoked).
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best regards,

Ted
Iliah
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« Reply #156 on: July 12, 2013, 11:49:08 AM »
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> mental masturbation
Jeff used it. I never even think of using such words.

> You might make more headway in persuading this forum that (effectively) what comes out of the camera is not what went in if you would use full sentences, give credible references, post illustrative images

I made a post providing data and description of what was done. Most of the discussion that followed is offtopic and in a lot of cases it is out of the line.
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xpatUSA
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« Reply #157 on: July 12, 2013, 12:09:55 PM »
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> mental masturbation
Jeff used it. I never even think of using such words.

Oops. Shame on Jeff, then  Wink

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> You might make more headway in persuading this forum that (effectively) what comes out of the camera is not what went in if you would use full sentences, give credible references, post illustrative images

I made a post providing data and description of what was done. Most of the discussion that followed is offtopic and in a lot of cases it is out of the line.

That you did, but I was talking about all of your posts and your literary style. If you see nothing wrong with those, then "as ye sow, so shalt thou reap"  Roll Eyes
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best regards,

Ted
Iliah
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« Reply #158 on: July 12, 2013, 12:13:43 PM »
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> "as ye sow, so shalt thou reap"

When in Rome
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xpatUSA
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« Reply #159 on: July 12, 2013, 01:56:47 PM »
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> "as ye sow, so shalt thou reap"

When in Rome ..

. . do [your imaging] as the Romans do  Grin

Happy sowing and reaping, I'm bowing out for now to give the heavy-weights a chance.

'Bye
« Last Edit: July 12, 2013, 02:04:19 PM by xpatUSA » Logged

best regards,

Ted
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