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Author Topic: Why do raw files require tone mapping to look perceptually correct?  (Read 10377 times)

faberryman

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #20 on: November 27, 2018, 07:04:48 pm »

If anything is inaccurate, it is probably my memory of the original scene rather than the digital capture itself.
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digitaldog

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #21 on: November 27, 2018, 07:08:23 pm »

Read the rest of the above-linked article, it has more examples of how lifeless the highlights are rendered, UNLESS one uses a -100 correction.

   
Increasing 'Exposure' even more heavily compresses the highlight tonality to avoid clipping or washing out, which can only be corrected by a negative Highlights correction (-100 in the example).

EDIT: Also read the section about "Brightening Highlights". Even the unadjusted histogram of the stepwedge shows tonal compression in the highlights.

Cheers,
Bart
That's just silly Bart. The two examples are utterly subjective and I suspect you can ask 100 people which the prefer and you'll get different answers from the group. Either is acceptable visually to me. But I'm NOT the image creator and I defer to the one rendering the image as they prefer. That's why we have the sliders in the first place; to render the image as we prefer.
You want to state that Zero isn't an ideal setting for your images? Fine. Don't use Zero. It's why we have the ability to produce our own defaults based on how we capture the image and wish to render it.
Meanwhile, unlike my example, we have no idea how the image was captured in terms of the raw data, a raw Histogram or info from RawDigger as to what really does reside somewhere within that range of highlights.
Again, I have no idea what point you're attempting to make other than LR/ACR sliders that affect highlights can affect highlights. To that I say "duh".  ;)
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kpz

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #22 on: November 27, 2018, 07:09:07 pm »

No. It's subjective. What I can recommend with the ACR/LR products is to consider working top down, left to right (for ACR) as the controls have been provided in an 'order' the designers believe should be used first. But you can break the rules. All edits are applied when rendering the raw in the best order, not the user order.

It doesn't seem entirely subjective to me. For example, it seems that most JPEG conversions do in general the same sorts of things, like adding contrast, and people usually find this more pleasing than the unmolested raw file. (That is, unless some special effect is desired. But for the "normal" photo look we are accustomed to, this seems roughly true.) This suggests some underlying technical or perceptual principles are at work.
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digitaldog

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #23 on: November 27, 2018, 07:09:17 pm »

If anything is inaccurate, it is probably my memory of the original scene rather than the digital capture itself.
Indeed! And the possible and massive difference in the dynamic range of what we can see and what we can capture as so well illustrated in this must read:
http://www.lumita.com/site_media/work/whitepapers/files/pscs3_rendering_image.pdf
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digitaldog

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #24 on: November 27, 2018, 07:09:49 pm »

It doesn't seem entirely subjective to me. For example, it seems that most JPEG conversions do in general the same sorts of things, like adding contrast, and people usually find this more pleasing than the unmolested raw file. (That is, unless some special effect is desired. But for the "normal" photo look we are accustomed to, this seems roughly true.) This suggests some underlying technical or perceptual principles are at work.
IF you think the JPEG is an ideal rendering, shoot JPEGs.  ;)
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kpz

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #25 on: November 27, 2018, 07:16:02 pm »

IF you think the JPEG is an ideal rendering, shoot JPEGs.  ;)

I certainly don't think the JPEG is an ideal rendering! It just seems that it is not entirely a matter of chance that raw converter defaults and in-camera renderers all do roughly similar things (again excepting special effects). I wouldn't call it "ideal," but I would say there is (broadly) some common, widely-preferred rendering style people expect when they see a "photo," and that it differs from straight scene referred input. I'd like to understand what that is and why people like it. Maybe it is a hopeless task, however.

That link you just posted a goes a long way toward answering my question, by the way!
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digitaldog

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #26 on: November 27, 2018, 07:20:37 pm »

I certainly don't think the JPEG is an ideal rendering! It just seems that it is not entirely a matter of chance that raw converter defaults and in-camera renderers all do roughly similar things (again excepting special effects). I wouldn't call it "ideal," but I would say there is (broadly) some common, widely-preferred rendering style people expect when they see a "photo," and that it differs from straight scene referred input. I'd like to understand what that is and why people like it. Maybe it is a hopeless task, however.

That link you just posted a goes a long way toward answering my question, by the way!
What straight scene referred input?
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kpz

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #27 on: November 27, 2018, 07:26:32 pm »

What straight scene referred input?

For instance the picture marked "scene referred image" in the link you posted earlier:
http://www.color.org/ICC_white_paper_20_Digital_photography_color_management_basics.pdf
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Bart_van_der_Wolf

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #28 on: November 27, 2018, 07:29:52 pm »

Meanwhile, unlike my example, we have no idea how the image was captured in terms of the raw data, a raw Histogram or info from RawDigger as to what really does reside somewhere within that range of highlights.

Try shooting a stepwedge if your senses do not see the highlight compression that many have been complaining about. Has nothing to do with Raw, but with the compressed rendering of the highlight tonality. The PV2012 highlight tonality compression has been complained about since it's inception. The Highlight control's ability to restore some sense is not just nice to have, it's a must, for many.

But hey, if you like washed out looking lifeless highlights, good for you.

Cheers,
Bart
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digitaldog

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #29 on: November 27, 2018, 07:30:50 pm »

For instance the picture marked "scene referred image" in the link you posted earlier:
http://www.color.org/ICC_white_paper_20_Digital_photography_color_management_basics.pdf
OK, that image is indeed scene referred because my co-author of the piece, Jack Holms of HP supplied it.
But anything else you see, in LR/ACR or any other raw converter that isn't specifically configured, IF possible for scene referred output is indeed output referred. Including everything we've seen here from Bart. That's important to keep in mind in this discussion. Ditto when someone is sharing a Histogram; it's not unless specifically produced as such, a raw Histogram. It's a Histogram of the currently rendered (and most often output referred) image.
It's a bit like trying to talk about the specific recipe for key lime pie by eating it alone. That's kind of a waste of time.
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digitaldog

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #30 on: November 27, 2018, 07:34:28 pm »

Try shooting a stepwedge if your senses do not see the highlight compression that many have been complaining about. Has nothing to do with Raw, but with the compressed rendering of the highlight tonality. The PV2012 highlight tonality compression has been complained about since it's inception. The Highlight control's ability to restore some sense is not just nice to have, it's a must, for many.

But hey, if you like washed out looking lifelesss highlights, good for you.

Cheers,
Bart
Waste of time Bart. You seem to be suggesting some agenda against how one raw converter allows us to alter a rendering. It's moot. If you cannot produce a rendering from a well captured raw, then you have a soap box to stand on. I could care less about compression when I can use or avoid it in producing an image I desire. Either of the waterfall images you provided (and now clearly didn't capture) is acceptable to me and I suspect others. If the author isn't happy with either, he's got a soapbox to stand on. Otherwise this is a solution in search of a problem that doesn't exist. And is kind of OT as well.
I have zero issues not getting (whatever lifeless highlights mean) in images I optimally expose with the ACR engine. But I think I did show that the original PV was a bit on the buggy side by default.
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digitaldog

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #31 on: November 27, 2018, 07:43:22 pm »

The PV2012 highlight tonality compression has been complained about since it's inception.
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Slobodan Blagojevic

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #32 on: November 27, 2018, 08:39:43 pm »

... The two examples are utterly subjective and I suspect you can ask 100 people which the[y] prefer and you'll get different answers from the group. Either is acceptable visually to me...

Ok, "prefer" is indeed subjective. And "acceptable" isn't really a high praise.

But let's rephrase the question. Let's ask 100 people which of the two they are more likely to use the following words to describe: dull, lifeless, flat. I am the first one to attached them to the first waterfall image. The OP does as well. I bet the majority of the 100 would do so.

And that really is the question the OP is asking since post #1: why are raw files generally perceived as more dull and flat, compared to adjusted files or even the out-of-camera jpegs.

My uneducated guess would be that raw files do not know which way users would like to go in post, so they offer a middle-of-the-road starting point, neither here nor there. If I may use an analogy, it is like a supermodel's picture in the morning, right out of bed, compared with the one after hours of makeup and hair styling. Now, of course, various people might prefer the natural look, but if asked which look would be more likely described as Plain Jane and which of a supermodel, the answers would be more unified.

digitaldog

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #33 on: November 27, 2018, 08:48:26 pm »

And that really is the question the OP is asking since post #1: why are raw files generally perceived as more dull and flat, compared to adjusted files or even the out-of-camera jpegs.
Because that's the default settings for one product, to produce an adjusted file that may match the out of camera JPEG. It's a starting point for the OP's product of use (Lightroom).
This isn't at all anything anyone has to accept. Anyone can easily change the default settings, as they can change the camera profile which alone will play huge role here.
Quote
My uneducated guess would be that raw files do not know which way users would like to go in post, so they offer a middle-of-the-road starting point, neither here nor there.
Raw files know nothing, they are 1's and zero's (like the JPEG). This is what raw looks like:



The raw needs to be rendered of course. How that's done is the name of the game here.
Someone may want to take Bart's bait and ask "well if ACR/LR can't render the step which (whatever why he thinks it should), what should I use instead. But the OP is using Lightroom, the ACR engine. And there's absolutely nothing that stops him, like perhaps 10's of thousands if not more knowledge uses, to render highlights and other areas of the tone curve as they desire. Case in point:


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Bart_van_der_Wolf

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #34 on: November 27, 2018, 09:17:04 pm »

Someone may want to take Bart's bait and ask "well if ACR/LR can't render the step which (whatever why he thinks it should), what should I use instead.

Huh?

All I'm saying is that the OP is correct, and that many people have a different preference than the, in this example, LR's default rendering.

I'm not arguing that it CAN be adjusted, but that it indeed SHOULD be adjusted in many cases, and that the reason is that LR's PV2012 (as it was called) attempts to compress highlight tonality separation as it attempts to avoid or reduce clipping. The latter (reducing/recovering) it does very well, the former (avoiding) leads to generally unwanted (by many) dullness in highlights, thus leading to an almost mandatory reduction in the Highlight control. Thus attempting to answer the OP's question.

Cheers,
Bart
« Last Edit: November 27, 2018, 09:21:41 pm by BartvanderWolf »
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digitaldog

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #35 on: November 27, 2018, 09:22:01 pm »

All I'm saying is that the OP is correct, and that many people have a different preference than the, in this example, LR's default rendering.
What default rendering from what camera, with what camera profile? And yet, we're told from your keyboard, to our eyes: The PV2012 highlight tonality compression has been complained about since it's inception. And But hey, if you like washed out looking lifeless highlights, good for you.
IF you have a different preference than the out of the box default settings with (what camera and profile, they DO differ), alter the default settings. Or yank on a slider. That's why they exist Bart.
But that was discussed in Post #3 before the OT, PV2012 tonality compression rabbit hole.
« Last Edit: November 27, 2018, 09:25:15 pm by digitaldog »
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kpz

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #36 on: November 27, 2018, 11:05:38 pm »

All I'm saying is that the OP is correct, and that many people have a different preference than the, in this example, LR's default rendering.

Thanks Bart.

While it may be entirely a personal artistic preference, as the Digital Dog notes, have you or others here noticed any other important "quirks" of the LR default rendering? And I suppose (based on some other posts of yours I have read) the ultimate "solution" is to try out Capture One? I'm just trying to understand the strengths and weaknesses of my tools, and what other options may be available to me.
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digitaldog

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #37 on: November 27, 2018, 11:17:53 pm »

There is a saying that a tool is only as good as the person using it.
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kpz

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #38 on: November 27, 2018, 11:23:35 pm »

There is a saying that a tool is only as good as the person using it.

Indeed, and I'll be the first to admit I have a ways to go in this direction. I'm just trying to understand how the thing works, so that I may use it better.
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digitaldog

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Re: Why do raw files require tone mapping to look perceptually correct?
« Reply #39 on: November 28, 2018, 09:36:02 am »

Indeed, and I'll be the first to admit I have a ways to go in this direction. I'm just trying to understand how the thing works, so that I may use it better.
Then I recommend you learn how to make import presets (and other presets) to produce an initial rendering you prefer as a starting point than looking at/asking about Capture 1 or any other product you presumably don't own nor know how to use.  ;)
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