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Author Topic: “Expose to the right” vs “JPEG Histogram to the right”  (Read 11134 times)

BJL

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #40 on: March 17, 2018, 09:51:36 PM »

Considering that exposure is Aperture and Shutter alone, what has ISO and ETTR got to do with this? Sorry, I still don't understand what you are suggesting. Amplification in the processing?
Yes: Ray takes ETTR to refer to the raw histogram after amplification, rather than the (hypothetical) sensor exposure histogram, so he is practicing and advocating what I call "amplify to the right". This was definitely of value with old-style Canon CMOS sensors, but see my long post above where I for one thing try to assess if and when there is any value to ATTR in the modern era of column-parallel ADC.
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Ray

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #41 on: March 17, 2018, 10:16:40 PM »

Considering that exposure is Aperture and Shutter alone, what has ISO and ETTR got to do with this? Sorry, I still don't understand what you are suggesting. Amplification in the processing?

Crikey! Andrew. Don't you believe in DXOMark graphs? Of course it's amplification in the processing; the camera processing in relation to the choice of ISO setting.

The attached graph shows the DR performance of the Nikon D810 compared with the Canon 5DSR and 5D Mk III.
If you underexpose by one stop at ISO 100, with the Canon cameras, you'll lose almost a full stop of DR, compared with using the same exposure of the same scene, from the same position, using the same F stop, at ISO 200.

If you underexpose by 2 stops at ISO 100, instead of an ETTR exposure at ISO 400 using the same shutter speed and f/stop, you'll lose almost 2 stops of DR. Isn't that an obvious deduction, from the graph?


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digitaldog

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #42 on: March 17, 2018, 10:44:51 PM »

Crikey! Andrew. Don't you believe in DXOMark graphs? Of course it's amplification in the processing; the camera processing in relation to the choice of ISO setting.
No but thanks for clarifying what you're referring to (that's why I asked).Thanks to BJL for doing so first.  ;)
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Andrew Rodney
Author “Color Management for Photographers"

Ray

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #43 on: March 18, 2018, 12:58:42 AM »

I've just stepped outside onto the deck at the rear of the house, and taken an ETTR shot in relation to ROTM (Right Of The Meter).  ;)

As you can see from the attached image, plus an enlargement of the histogram in Adobe Camera Raw before any adjustments have been made, it's not quite an ETTR exposure.

In this particular instance, I could have given at least 2/3rds of a stop more exposure before clipping any of the channels, so my general procedure of exposing to the far right of the camera's metering scale is a conservative approach to ensure that the brightest parts of the composition which I might have missed due to a lack of time to check every bright patch in the scene, are not blown.

In this particular shot, the brightest part of the scene is easily discernible, so I've really nailed it, as the histogram shows.
Since I'm not anally retentive, and since I use a camera with an extremely high DR rating, I'm not at all concerned about sacrificing a mere 2/3rd's of a stop of DR.  ;)

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digitaldog

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #44 on: March 18, 2018, 10:03:31 AM »

I've just stepped outside onto the deck at the rear of the house, and taken an ETTR shot in relation to ROTM (Right Of The Meter).  ;)

As you can see from the attached image, plus an enlargement of the histogram in Adobe Camera Raw before any adjustments have been made, it's not quite an ETTR exposure.
You don’t seem to recognize that indeed there is an adjustment in ACR.You don’t seem to recognize that the histogram shown in ACR tells you very little if anything about the actual exposure. You don’t seem to recognize this histogram is a rendered histogram of the current editing settings. Move exposure slider or highlight all the way to the right. Or left! How’s that histogram look? How does that Histogram correlate to your exposure of the raw data? It does not! Now try Rawdigge.
« Last Edit: March 18, 2018, 11:01:56 AM by andrewrodney »
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Andrew Rodney
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jrsforums

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #45 on: March 18, 2018, 12:02:19 PM »

You don’t seem to recognize that indeed there is an adjustment in ACR.You don’t seem to recognize that the histogram shown in ACR tells you very little if anything about the actual exposure. You don’t seem to recognize this histogram is a rendered histogram of the current editing settings. Move exposure slider or highlight all the way to the right. Or left! How’s that histogram look? How does that Histogram correlate to your exposure of the raw data? It does not! Now try Rawdigge.

Just to add to what Andrew says, LR/ACR has significant highlight compression and roll off.  My tests, years ago, on 5D3, showed that almost all highlights with rendered highlights above 96-97% showed at least one blown channel when looked at in RawDigger.
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John

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #46 on: March 18, 2018, 02:52:34 PM »

... I am rather confident that there is a simple and easily-determined approximate relationship between the camera's JPEG histogram (at default settings for contrast etc.) and what the raw histogram would tell you, so the camera's histogram can probably get you within 1/2 stop of perfection once one adds a suitable shift to what that histogram suggests. Not perfect due to issue like one color being blown out ...

BJL, - there were some excellent posts by Bill / bjanes in previous discussions on this subject.
I'm sure you are aware, however, I thought it is worthwhile to remember it here:

http://forum.luminous-landscape.com/index.php?topic=96523.msg788460#msg788460
http://forum.luminous-landscape.com/index.php?topic=96523.msg788730#msg788730
http://forum.luminous-landscape.com/index.php?topic=68334.msg587241#msg587241

Peter
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Ray

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #47 on: March 18, 2018, 08:46:02 PM »

You don’t seem to recognize that indeed there is an adjustment in ACR.You don’t seem to recognize that the histogram shown in ACR tells you very little if anything about the actual exposure. You don’t seem to recognize this histogram is a rendered histogram of the current editing settings. Move exposure slider or highlight all the way to the right. Or left! How’s that histogram look? How does that Histogram correlate to your exposure of the raw data? It does not! Now try Rawdigge.

Of course I realize that there are thousands of adjustments that have been made from the time I press the shutter button to the time the file is demosaiced in Adobe Camera Raw. Those adjustments are in accordance with the camera design and the software design. I have little control over them.

ACR is the software I've been using for many years. If I were dissatisfied with it, I'd switch to other software, just as I switched from Canon to Nikon many years ago. The D700 was my first Nikon camera which replaced my Canon 5D

As I've mentioned before, if nothing appears to be blown in the highlights and nothing appears to be wrong or odd, then it's of no concern to me. If it ain't broke then don't fix it.

Also, how could you possibly assume that anyone would use ACR without making adjustments with the sliders. I move various sliders from left to right every time I process a RAW image. I obviously must know how it changes the histogram. Did you miss the point that the image in my previous post was to show how it looked before I'd made any adjustments.

Sometimes I'll move the exposure slider to the right, even though the image does not look underexposed, and compensate for it by moving the highlights and whites sliders to the left, because that has the desired effect on other parts of the image.

My general procedure is to process the image first in ACR, moving the appropriate sliders, and making other adjustments till the image looks right, then fine tune the image after opening in Photoshop in 16 bit mode using the ProPhoto RGB color space. Okay?

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digitaldog

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #48 on: March 18, 2018, 08:57:37 PM »

Of course I realize that there are thousands of adjustments that have been made from the time I press the shutter button to the time the file is demosaiced in Adobe Camera Raw. Those adjustments are in accordance with the camera design and the software design. I have little control over them.
The discussion was exposure and Histograms, you provided some in ACR. It doesn't tell us the truth about the raw exposure.

Quote
As I've mentioned before, if nothing appears to be blown in the highlights and nothing appears to be wrong or odd, then it's of no concern to me. If it ain't broke then don't fix it.
Despite the possibility of over exposing your data.
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Andrew Rodney
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Ray

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #49 on: March 18, 2018, 10:42:03 PM »

Despite the possibility of over exposing your data.

Absolutely! My method of correctly exposing for the highlights, as I've described in great detail, ensures that there are no visible effects of blown highlights in ACR, which is the program I'm accustomed to.

Invisible effects of blown highlights, which might only be apparent in Rawdigger, are of little concern. Why should they not be? I'm not in the job of designing software for RAW files. If Adobe has succeeded in repairing, correcting or even obscuring any slight effects of blown highlights, then 'good on them' I say. Well done! ;D
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digitaldog

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #50 on: March 19, 2018, 09:13:08 AM »

Absolutely! My method of correctly exposing for the highlights, as I've described in great detail, ensures that there are no visible effects of blown highlights in ACR, which is the program I'm accustomed
If you over exposed, (you admit the possibility) You didn’t expose correctly as you view another lie of a Histogram: Going back to my first recommendation: use the right tool for the right job if you must have to view a Histogram to property expose (photography 101). That isn’t ACR! It’s Rawgigger; no lie, just the facts Man 😋
« Last Edit: March 19, 2018, 11:10:38 AM by andrewrodney »
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Andrew Rodney
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Ray

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #51 on: March 19, 2018, 09:48:20 AM »

If you over exposed, (you admit the possibility) You didn’t expose correctly as you views another lie of a Histogram: Going back to my first recommendation: use the right tool for the right job if you just have to few a Histogram to property expose (photography 101). That isn’t ACR! It’s Rawgigger; no lie, just the facts Man 😋

Andrew,
I'm aware of the effects of overexposure, just as I'm aware of noise and banding in deep shadows, with some models of camera. Both the Canon 5D and the Nikon D7100 upset me because I could see banding in the shadows, although the banding in the D7100 shots was only visible in much deeper shadows than in the 5D shots.

I'm getting the impression, if I were to use Rawdigger instead of ACR, I would tend to use a faster shutter speed to avoid blowing highlights which were not visibly blown in ACR. Is that correct?

If I were to use a faster shutter speed, all else being the same, the noise in the shadows would increase. Is that correct?
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Dave Rosser

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #52 on: March 19, 2018, 09:54:34 AM »

You do make things difficult  ::)
Getting the right exposure has not changed in 60 years.  I just shot the view up my road using British Standard Exposure Tables B.S.935/1957 (incorporated in the handy calculator shown in picture below) to estimate the exposure. The first picture shows result in fast RAW viewer. It could perhaps have stood a 1/3rd stop more exposure for absolute perfection but...
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digitaldog

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #53 on: March 19, 2018, 10:13:23 AM »

Andrew,
I'm aware of the effects of overexposure, just as I'm aware of noise and banding in deep shadows, with some models of camera. Both the Canon 5D and the Nikon D7100 upset me because I could see banding in the shadows, although the banding in the D7100 shots was only visible in much deeper shadows than in the 5D shots.

I'm getting the impression, if I were to use Rawdigger instead of ACR, I would tend to use a faster shutter speed to avoid blowing highlights which were not visibly blown in ACR. Is that correct?

If I were to use a faster shutter speed, all else being the same, the noise in the shadows would increase. Is that correct?
Don’t you have RawDigger and can’t you like others posting here who do, run your own tests on your own sensors?????
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Andrew Rodney
Author “Color Management for Photographers"

BJL

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #54 on: March 19, 2018, 10:36:15 AM »

BJL, - there were some excellent posts by Bill / bjanes in previous discussions on this subject.
I'm sure you are aware, however, I thought it is worthwhile to remember it here:

http://forum.luminous-landscape.com/index.php?topic=96523.msg788460#msg788460
http://forum.luminous-landscape.com/index.php?topic=96523.msg788730#msg788730
http://forum.luminous-landscape.com/index.php?topic=68334.msg587241#msg587241

Peter
--
Thanks! I do somewhat recall some of those conversations, with input from experts like Bill Janes, but I am sure that I can benefit from reading more.

For one thing, I realize that my previous description was naive about the shape of the tone curve underlying a camera's default JPEG conversions and its displayed histogram. (Is it a safe assumption that when one is shooting for the raw files, the camera's JPEG settings can be at defaults?) Even if midtones are placed close to the standards-specified JPEG level 112, about 2.5 stops below maximum, the defaults tone curves roll off a bit above that, so that the maximum JPEG level corresponds to scene brightness more than 2.5 stops above the midtones.
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digitaldog

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #55 on: March 19, 2018, 11:08:19 AM »

For one thing, I realize that my previous description was naive about the shape of the tone curve underlying a camera's default JPEG conversions and its displayed histogram. (Is it a safe assumption that when one is shooting for the raw files, the camera's JPEG settings can be at defaults?) Even if midtones are placed close to the standards-specified JPEG level 112, about 2.5 stops below maximum, the defaults tone curves roll off a bit above that, so that the maximum JPEG level corresponds to scene brightness more than 2.5 stops above the midtones.
Considering we can pick between sRGB which doesn't have a gamma curve but a TRC and Adobe RGB (1998) which has a gamma curve, one could assume (and I hate to do so), there would be small differences. Another reason why the JPEG Histogram, a lie, isn't all that useful:

Everything you thought you wanted to know about Histograms
Another exhaustive 40 minute video examining:

What are histograms. In Photoshop, ACR, Lightroom.
Histograms: clipping color and tones, color spaces and color gamut.
Histogram and Photoshop’s Level’s command.
Histograms don’t tell us our images are good (examples).
Misconceptions about histograms. How they lie.
Histograms and Expose To The Right (ETTR).
Are histograms useful and if so, how?


Low rez (YouTube): http://www.youtube.com/watch?v=EjPsP4HhHhE
High rez: http://digitaldog.net/files/Histogram_Video.mov
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Andrew Rodney
Author “Color Management for Photographers"

kirkt

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #56 on: March 19, 2018, 12:48:37 PM »

You do make things difficult  ::)
Getting the right exposure has not changed in 60 years.  I just shot the view up my road using British Standard Exposure Tables B.S.935/1957 (incorporated in the handy calculator shown in picture below) to estimate the exposure. The first picture shows result in fast RAW viewer. It could perhaps have stood a 1/3rd stop more exposure for absolute perfection but...

For what is being discussed here (ETTR or optimal raw exposure) that shot is at least 1 to 1-1/3 stops underexposed (eyeballing the histogram), according to the raw histogram.  That is, the green channel's brightest highlight (probably in the non-specular snow) falls to zero frequency well below sensor clipping such that the exposure could be increased by over 1 stop and still not produce sensor clipping in areas of meaningful detail.  If the deep shadows were of concern in this image, you could probably push the highlights in the snow even more and rely upon highlight compression and reconstruction to bring the neutral highlights back from clipping from the unclipped red and blue channels, giving the shadows even more signal to work with.  How much more would depend upon the raw converter and the various highlight reconstruction strategies they employ.  Exposing for a particular raw converter's capability is a bit of a gamble - it may give you extra exposure to work with now, but if you ever change converters you may have to deal with the consequences of pushing your luck a little too far if that other converter does not employ the same highlight reconstruction strategy.  This is why the raw histogram is so useful.

During raw conversion the exposure would need to be pulled back to reestablish the tonal representation of the scene, but that is part of using the ETTR technique.

kirk
« Last Edit: March 19, 2018, 01:14:20 PM by kirkt »
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Dave Rosser

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #57 on: March 19, 2018, 01:48:02 PM »

For what is being discussed here (ETTR or optimal raw exposure) that shot is at least 1 to 1-1/3 stops underexposed (eyeballing the histogram), according to the raw histogram.  That is, the green channel's brightest highlight (probably in the non-specular snow) falls to zero frequency well below sensor clipping such that the exposure could be increased by over 1 stop and still not produce sensor clipping in areas of meaningful detail.  If the deep shadows were of concern in this image, you could probably push the highlights in the snow even more and rely upon highlight compression and reconstruction to bring the neutral highlights back from clipping from the unclipped red and blue channels, giving the shadows even more signal to work with.  How much more would depend upon the raw converter and the various highlight reconstruction strategies they employ.  Exposing for a particular raw converter's capability is a bit of a gamble - it may give you extra exposure to work with now, but if you ever change converters you may have to deal with the consequences of pushing your luck a little too far if that other converter does not employ the same highlight reconstruction strategy.  This is why the raw histogram is so useful.

During raw conversion the exposure would need to be pulled back to reestablish the tonal representation of the scene, but that is part of using the ETTR technique.

kirk
In practice I use ETTR on my X-Pro1.  On the X-Pro 1 you can set the camera up to provide a soft contrast JPEG pre-view image and thus a histogram that reveals the most information about dynamic range for RAW files. The settings I use are
Dynamic Range - DR100%
Film Simulation - Provia
Highlight Tone - (-2) Soft
Shadow Tone - (-2) Soft
These internal RAW developer settings affect the histogram seen in viewfinder even though I am shooting RAW only.
I see this somewhat optimised histogram in the viewfinder and can adjust the exposure compensation dial with my right thumb to move the histogram to the right (or left if the meter is overexposing).

BTW you were right - one stop under exposed.
Here is the picture after correction in Capture One and it could have done with that extra 1 stiop to bring out detail in the shrub across the road. :-[

« Last Edit: March 19, 2018, 02:13:52 PM by Dave Rosser »
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digitaldog

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #58 on: March 19, 2018, 01:52:25 PM »

During raw conversion the exposure would need to be pulled back to reestablish the tonal representation of the scene, but that is part of using the ETTR technique.
kirk
Michael called it "Normalization" and I think it is still a good name. Some folks open a raw exposed optimally for raw, they believe there are 'no settings' applied when there always is and this default setting is utterly wrong for this kind of capture. It's like in the 'old days' when people would state that Linear encoded captures were dark. Yeah, if you viewed them incorrectly with a gamma corrected assumption, they looked awful. Assign the correct ICC profile that defines this capture, it doesn't appear dark at all (unless the photographer didn't expose correctly)!  :o I recall some Kodak DCS cameras that produced this option and have such captures in archive. They needed 'normalization' too. The data was just fine.
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Andrew Rodney
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BJL

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Re: “Expose to the right” vs “JPEG Histogram to the right”
« Reply #59 on: March 19, 2018, 01:53:22 PM »

Crikey! Andrew. Don't you believe in DXOMark graphs? Of course it's amplification in the processing; the camera processing in relation to the choice of ISO setting.

The attached graph shows the DR performance of the Nikon D810 compared with the Canon 5DSR and 5D Mk III.
Those are some rather old cameras, form before Canon adopted column-parallel ADC, so here are some more up-to0-date comparisons. I use the "print" graphs, rescaled to compensate for different pixel counts. (This is even after I momentarily put aside DXO's outright error in the horizontal scale (through its confounding the upper limit of raw files with Exposure Index), and the roughly counteracting adjustment needed to discount measures of highlight headroom and instead assess shadow handling.)

There is still the dubious relevance of the bottom few stops of that "engineering" dynamic range, going down to a photographically useless SNR=1. One way to dig our some information about SNR in the deep shadows is to look at DXO's "SNR 18%" graphs. Directly, they refer to SNR in the "mid-tones" at the stated EI, but also, the values at one high EI roughly reflect SNR at a level "x" stops lower when using an EI x stops lower. For example, SNR 18% at EI=25,600 is from photosites getting the same illumination as photosites 5 stops below mid-tones [about 8 below the top of the DR] in exposure at EI=800, and those 8 stops below mid-tones [about 11 below the top of the DR] at EI=100.

Then all three cameras perform very similarly, hitting the 20dB level (which corresponds to SNR = 10:1, a guideline for minimum tolerable SNR as embodied in the ISO SNR10:1 measure of shadow handling) at EI between 25,600 and 51,200. This suggests to me — but by no means proves! — that the differences in the DXO DR graphs are mostly due to different behavior in the irrelevant lower stops where SNR is too low to be "photographically useful".
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