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Author Topic: good histogram = dark images in surf pics...  (Read 5427 times)
Vladimirovich
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« Reply #20 on: March 17, 2014, 11:42:29 AM »
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If the pictures turn out consistently too dark, exposure metering is doing a wrong evaluation of the subject, really nothing more to it. Quite usual, actually, if the subject is lighter or darker than average, for which the exposure is calibrated. Just simply turn the exposure compensation dial to +1 or +1.5, problem is likely to be fixed, that is why cameras have that function. No need to dwell deeply into conversion theories or purchase better/different RAW converters.

I'd say no need to use raw converters at all - just use camjpg
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Vladimirovich
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« Reply #21 on: March 17, 2014, 11:45:48 AM »
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I agree totally up to the point about better/different raw converters. I don't see how we can separate exposure from processing. But yes, your suggestion about expsoure compensation is exactly how I handle ETTR. The first part is of course gauging via brackting how much to compensate and to do that, at least I have to bring the raw's into LR and see how far I can go before I've really blown out highlights I want to retain. From there, it's exposure 101.
and I using LR Rawdigger can tune real time (pre shot) blinkies (E-M1) or zebra (A7) to show me when clipping starts in raw with less than 1/3 EV precision and understand what is the headroom in raw when I do spot metering.. that is I don't need clueless histogram in LR/ACR at all... that is exposure 101 nowadays.
« Last Edit: March 17, 2014, 03:56:13 PM by Vladimirovich » Logged
digitaldog
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« Reply #22 on: March 17, 2014, 11:46:16 AM »
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the problem is - people shall not think in terms of LR/ACR w/o understanding what LR/ACR does with the data and what is data that LR/ACR deals with... why do you want to cripple their knowledge ?
No but I don't see that as very relevant. ACR/LR does as we both agree, do something with that data. Unless we decide not to use that specific converter, it's going to do what it's going to do and that IS part of the entire process. Or to put it another way, if we agree the OP and other's will use LR/ACR, and Rawdigger shows something vastly different from LR/ACR, what's the user to do? They have to take that processing into account. Just as a lab's E6 processing in LA may differ from E6 processing in NY. Yes, in a perfect world, they would be identical. At least when I shot a lot of E6 film, it always went to one lab (A&I Color), I always ran exposure and filter tests from each emulation batch I'd buy. And I did have to alter the process a bit. Again, I'm wondering HOW one can separate exposure and processing without tieing yourself up in knots.
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Andrew Rodney
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« Reply #23 on: March 17, 2014, 11:48:24 AM »
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that is I don't need clueless histogram in LR/ACR at all... that is exposure 101 nowadays.
Agreed. And further, seeing clipping in color or channel OVER the image in LR/ACR is vastly more useful than looking at a Histogram. The problem becomes when the clipping really is clipped data and as you say, that's exposure 101. No histogram needed in either product. By and large, Histograms have been over sold.
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Andrew Rodney
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BartvanderWolf
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« Reply #24 on: March 17, 2014, 11:56:56 AM »
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But if that's the process used to render the raw's, how is that a problem?

Because it doesn't tell what is going on, and how to address the issue at the core (correct exposure). Besides, there are other converters than LR/ACR which do show the real situation without the 'PV2012 black magic'.

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If one wants to understand the effect of the exposure + processing on their raws, and assuming they want to use LR/ACR, I don't see how this is a problem.

Because one doesn't learn to address the real fundamental issue with exposure, just how LR/ACR handles it. If one switches to another (superior) Raw converter one may learn all of a sudden that the Raw files were incorrectly exposed from the start, potentially beyond correction with anything else than LR/ACR, or with sub-optimal exposure.

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What am I missing in such an approach?

An unbiased advice? The truth (not just the one according to Adobe but), the whole truth, and nothing but the truth?
It's just like with politicians, they don't lie, they just do not tell the whole truth.

Cheers,
Bart
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bjanes
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« Reply #25 on: March 17, 2014, 12:05:59 PM »
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LR/ACR, at least with PV2012 and the default tone curve, is not good for evaluating overexposure since automatic highlight recovery is employed and an exposure offset is used. With Nikon cameras it +0.5 EV for the D3 and + 0.35 for the D800e.

But if that's the process used to render the raw's, how is that a problem?
If one wants to understand the effect of the exposure + processing on their raws, and assuming they want to use LR/ACR, I don't see how this is a problem. The rendering, the clipping (or lack of clipping both exposure and saturation) are the reality of what is currently being seen in the raw converter. Why not simply deal with the processing as we've done in the past with film? That being, your exposure and processing are tied at the hip. Bracket under controlled lighting. Bring raws into LR/ACR. Use PV2012 or not, depending on your preference. What you see is what you get here: exposure plus processing. What am I missing in such an approach?

Andrew,

I do use LR PV2012 to render most of my raw files with good results, but it helps to know how the converter is handling the raw file. If one is exposing to the right and using the LR/ACR histogram to judge exposure and you don't take the offset into account, you may not  be exposing optimally.

Bill
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bjanes
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« Reply #26 on: March 17, 2014, 12:12:14 PM »
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Because one doesn't learn to address the real fundamental issue with exposure, just how LR/ACR handles it. If one switches to another (superior) Raw converter one may learn all of a sudden that the Raw files were incorrectly exposed from the start, potentially beyond correction with anything else than LR/ACR, or with sub-optimal exposure.

Bart,

I do know that you are no fan of Adobe products, but the LR workflow does work well for many of us and the file handling and printing features are worth a minimal loss of image quality. For exhibition prints or special images, one still has the raw file and might wish to use better tools. A much requested feature of ACR is to have a switch to show the raw histogram such as is available in Raw Therapee. Eric Chan, are you listening?

Bill
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digitaldog
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« Reply #27 on: March 17, 2014, 12:13:04 PM »
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Because it doesn't tell what is going on, and how to address the issue at the core (correct exposure). Besides, there are other converters than LR/ACR which do show the real situation without the 'PV2012 black magic'.
Exactly, the processing is part of the total equation. What's going on in LR is what's going on in LR, the product we are supposedly using. Switch products and yes, I expect a different result to some degree. The processing is different. Are you saying that Rawdigger IS the ultimate info, and that it's raw converter processing agnostic? Even if true, you still can't separate the processing which is converter specific. So perhaps if this product is free and you can run it, seeing the bracket test would tell you something about actual raw clipping separate from processing. Unless you decide it's your raw converter of choice, you simply have to move past it and see the results of the bracket in the converter you intend to use. Rawdigger isn't necessary, it's an interesting (for some) data point.

One could say, use Rawdigger to find true raw clipping but you to then move the data into the converter of choice and work from there no?

Let's use the E6 analogy. Lab in NY that I don't use conforms to the E6 standards exactly, A&I lab in LA that I use is off. But I'm targeted to A&I, the processing. Knowing what the E6 standard aim point is and who hits it (Rawdigger) is interesting. But it doesn't help me at all as I'm using A&I in LA (LR/ACR). IF I move to NY, I'll consider my next move. That move has to involve the processing.
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Andrew Rodney
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« Reply #28 on: March 17, 2014, 12:19:17 PM »
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Here is an image taken by the D3 with overexposed yellows as shown by Rawdigger:
I don't use this product so forgive me if this is a stupid question. You say overexposed yellow. I assume on channel is blown out. Based on what color space?
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Andrew Rodney
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BartvanderWolf
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« Reply #29 on: March 17, 2014, 12:53:12 PM »
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I do know that you are no fan of Adobe products, but the LR workflow does work well for many of us and the file handling and printing features are worth a minimal loss of image quality.

Hi Bill,

I use Photoshop every day, and I occasionally use Lightroom. So it's not that I don't like Adobe products, but I do have some reservations about the Raw conversion quality. When I do use LR/ACR for Raw conversion, it's mainly for convenience but not for quality.

Since I usually do not have to process large volumes, I tend to aim for quality, which steers me to e.g. Capture One Pro (also allows LCC correction with automatic dust removal), or RawTherapee (with Amaze or other dedicated (e.g. for High ISO noise) conversion algorithms and CIECAM color corrections), for Raw conversion, and then to Photoshop for layer based postprocessing.

However, it all starts with optimized exposure, and learning from experience how to achieve that in camera is important. When a Raw converter becomes an obstacle to learning that optimal exposure and delivers sub-optimal raw conversions to boot, I'll warn others about that because I think they should know the full story. When people are fully informed, they can choose whatever compromise they want. I don't really care what others use, but I do care when people are being spoon-fed only half truths.

The OP is experiencing an issue, maybe caused by exposure technique, that can presumably be solved with proper technique. He is probably better helped by solid advice than by ways to mask/hide his fundamental issues by using a tool 'XYZ'.

Cheers,
Bart
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bjanes
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« Reply #30 on: March 17, 2014, 02:03:23 PM »
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I don't use this product so forgive me if this is a stupid question. You say overexposed yellow. I assume on channel is blown out. Based on what color space?

This would be the red channel is focally blown out to the extent of 3.6% of the red pixels as shown by Rawdigger. The color space would be that of the raw file (if you accept a raw file as having a color space--I would prefer not to re-argue that topic  Smiley). When the file is rendered into ProphotoRGB with ACR, there is strong clipping of the red channel due white balance (Rawdigger reports the red multiplier as 1.70 for the as shot white white balance). If one were rendering with DCraw, one could use the -H 1 option to use multipliers less than or equal to unity (see Guillermo Luijk). With ACR one can use negative exposure to obtain the same effect (AFAIK).

Bill
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digitaldog
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« Reply #31 on: March 17, 2014, 02:05:39 PM »
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The color space would be that of the raw file (if you accept a raw file as having a color space--I would prefer not to re-argue that topic  Smiley).
I don't want to go there either. But some assumption is made, that would affect the results right? Or there is a margin after which, no assumed color space could account for this being anything but clipping?
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Andrew Rodney
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Vladimirovich
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« Reply #32 on: March 17, 2014, 03:39:32 PM »
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He is probably better helped by solid advice than by ways to mask/hide his fundamental issues by using a tool 'XYZ'.

Ceterum censeo Carthaginem esse delendam (c)
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Vladimirovich
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« Reply #33 on: March 17, 2014, 03:42:18 PM »
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A much requested feature of ACR is to have a switch to show the raw histogram such as is available in Raw Therapee. Eric Chan, are you listening?
it is not going to happen because the whole point of Adobe's approach is to move away from raw data as soon as possible and perform as little operations there as possible...
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Vladimirovich
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« Reply #34 on: March 17, 2014, 03:53:25 PM »
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Are you saying that Rawdigger IS the ultimate info

as of today it is a the best usable tool to study your camera in terms how exposure and gain affects the raw data... now - that does not mean that raw converter is irrelevant - as many people many times stated here and elsewhere (including people developing rawdigger) you need to pay attention to what is your raw converter - because different raw converters might have different issues when exposure correction is performed (for example twisted DCP profiles) or for example some raw converters are not that good in handling the colors where raw is clipped in (1, 2, + channels), etc...

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msongs
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« Reply #35 on: March 20, 2014, 02:57:02 AM »
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hey thanks to all the interesting information you have posted. will be doing some more surf pics next week using info from the web, youtube, and here. hope to get better results on exposure and all. its a drag using a fast shutter speed and then the camera wont take a pic because it cant set an f/stop lol.  I guess that's where exposure compensation comes in. thanks again tho.
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Msongs
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hjulenissen
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« Reply #36 on: March 20, 2014, 04:31:58 AM »
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If the pictures turn out consistently too dark, exposure metering is doing a wrong evaluation of the subject, really nothing more to it. Quite usual, actually, if the subject is lighter or darker than average, for which the exposure is calibrated. Just simply turn the exposure compensation dial to +1 or +1.5, problem is likely to be fixed, that is why cameras have that function. No need to dwell deeply into conversion theories or purchase better/different RAW converters.
I don't think that image brightness should be solved by in-camera exposure. When operating the camera, I want to maximize the quality of recorded info (within subjective and practical constraints).

I might like to _render_ the image as e.g. high-key, but that can be better and more predictably solved in my raw editor, rather than risking clipping one or more camera channels.

As cameras get more DR, it makes sense that the exposure system "spends" this DR for both highlight headroom and noise footroom. Thus, "middle gray" might be positioned further away from highlights in 2015 cameras than it was in 2005 cameras.

-h
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jjj
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« Reply #37 on: March 20, 2014, 05:49:31 AM »
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If the pictures turn out consistently too dark, exposure metering is doing a wrong evaluation of the subject, really nothing more to it. Quite usual, actually, if the subject is lighter or darker than average, for which the exposure is calibrated. Just simply turn the exposure compensation dial to +1 or +1.5, problem is likely to be fixed, that is why cameras have that function. No need to dwell deeply into conversion theories or purchase better/different RAW converters.
I was just about to say the same. Learn to use the camera metering properly or maybe even try a light meter.
Also unless the sun is darting out from behind clouds at random intervals, you can set the camera manually and leave the exposure alone. Even easier than faffing exposure compensation.
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« Reply #38 on: March 20, 2014, 05:55:19 AM »
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I don't think that image brightness should be solved by in-camera exposure. When operating the camera, I want to maximize the quality of recorded info (within subjective and practical constraints).
Which is set by in-camera exposure.  Roll Eyes

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I might like to _render_ the image as e.g. high-key, but that can be better and more predictably solved in my raw editor, rather than risking clipping one or more camera channels.

As cameras get more DR, it makes sense that the exposure system "spends" this DR for both highlight headroom and noise footroom. Thus, "middle gray" might be positioned further away from highlights in 2015 cameras than it was in 2005 cameras.
And you do that by getting the 'correct' exposure in camera. 'Correct' exposure depends entirely on how you want image to look.
Don't like ETTR myself for example. Yes it may collect more information, but I'm a photographer not a forensic analyst, so I don't get upset by my shadows being black as that's maybe how I want them to look.  Smiley
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hjulenissen
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« Reply #39 on: March 20, 2014, 06:17:22 AM »
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Which is set by in-camera exposure.  Roll Eyes

 And you do that by getting the 'correct' exposure in camera. 'Correct' exposure depends entirely on how you want image to look.
Don't like ETTR myself for example. Yes it may collect more information, but I'm a photographer not a forensic analyst, so I don't get upset by my shadows being black as that's maybe how I want them to look.  Smiley
I think that when you think about the difference between "exposure" and "brightness", you will realize that camera manufacturers lump these two related concepts together for no apparent good reasons (at least for raw shooters, but then raw shooters seems to not be the main focus of manufacturers anyways).
http://www.cambridgeincolour.com/tutorials/camera-metering.htm
http://en.wikipedia.org/wiki/Middle_gray

If you want large parts of your scene rendered very bright (on paper, display), I can see little reason to clip (one or more channels of) the camera sensor to achieve this. A better method would be to expose just like an audio engineer would adjust mixing console input levels (capture the performance, sans clipping), then do whatever editing after the fact.

There are situations where clipping in camera is a sensible compromise, but again, I find that the camera exposure system is more like a relic from the 80s, than the tool one might hope for in 2014.

People have made all kinds of work-arounds for this. ala: "On Nikon cameras, I apply +1.5 stop of EC when doing green landscape". "On Sony cameras, I do -0.5 stop of EC when shooting the night sky". "I always shoot each scene a number of times, inspecting the in-camera preview for blinkies before readjusting exposure". While these no doubt work for people making great photographies, it is hardly an intuitive or user-friendly method of working.

-h
« Last Edit: March 20, 2014, 06:39:01 AM by hjulenissen » Logged
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