Brightness vs shadow recovery

[digitaldog]

Good luck with that! As long as the cur keeps barking and attacking, civilized discussions are nearly impossible.

Then stop and get back on the topic. Maybe you'll learn something.

"Listen to understand instead of listening to respond." - Barack Obama

[Ed_Ingold]

Technically speaking, "exposure" is the net amount of light (intensity x time) falling on the sensor. Yet every software program I've seen has a slider marked "exposure." LOL, perhaps we need to rename it in German fashion by stringing descriptive phrases together without spaces, for example, "slidertoraisetheoverallloutputlevel."

 

In keeping with this, I made a label for my CF95 lamp, "bildsehenbeleuchtung."

[conrad_hoffman]

Terminology drives me nuts. It's hard enough to keep things straight myself without companies deciding to repurpose it to their own desires. I see it in lots of places, in software, in specifications and when companies want to create a narrative around products that's different from others. It's been true at most places I've worked. The danger is that people with no background will erroneously associate terms with the wrong thing, and it's almost impossible to unlearn it.

[digitaldog]

Technically speaking, "exposure" is the net amount of light (intensity x time) falling on the sensor.

Yes, "we've" covered that fact.

Yet every software program I've seen has a slider marked "exposure."

You may wish to look at more examples but anyway:

"If fifty million people say a foolish thing, it is still a foolish thing."

-Bertrand Russell

Lastly, in terms of what controls are called in software versus using correct terminology: as the Chinese proverb says: "The first step towards genius is calling things by their proper name."

[samstevens]

Language disguises the thought; so that from the external form of the clothes one cannot infer the form of the thought they clothe, because the external form of the clothes is constructed with quite another object than to let the form of the body be recognized.

―Ludwig Wittgenstein

In terms of the "exposure" control in Photoshop, for example, I never took "exposure" in that context to be representative of a scientific fact so much as a user-friendly idea. In other words, I took it metaphorically. Those who take it as fact are likely no worse for it. Those who know it not to be fact will likely be the only ones concerned about it but they won't be fooled by it, so no harm done.

 

At which point ...

A man will be imprisoned in a room with a door that's unlocked and opens inwards; as long as it does not occur to him to pull rather than push.

―Ludwig Wittgenstein

[digitaldog]

Let’s examine the EXACT question: “Sometimes I take photos that are way underexposed due lack of light. what is the correct way to bump up the exposure?”

Now the OP knows what’s exposure is, he may ask “What’s the best way to bump up brightness?” or maybe he really does want (and should strive) for ideal exposure at capture. He can rephrase the question or not.

The OP is speaking of photography, he’s speaking of exposing sensor data and he is having issues under exposing and wants to bump up exposure. This has NOTHING to do with software because exposure takes place at capture based on two and only two attributes (no, not ISO). Those that wish to speak of a slider or control in software named “Exposure” are not helping, going OT and adding to the confusion of others as they may be confused about photographic exposure. THAT is the question and topic. I provided a number of URLs about producing optimal exposure from a number of peer reviewed outside references.

“Exposure” control in software, Photoshop or otherwise has nothing to do with photographic exposure. It doesn’t matter how many software products use that name, it has nothing to do with exposing image data!

Other text provided without an ounce of proof about what the sliders do (in undefined software products with undefined data) is equally non-useful to the OP and only serves to confuse others who know less about the subject than those posting the misinformation.

[samstevens]

The OP, in essence, asked two questions, one about exposure and one about adjusting for an under exposure at the software stage by using brightness and shadows. That was answered in the first response, with the distinction clearly made. Only the man who seems to have a need to be at the top of the totem pole made it more difficult and complicated than it needed to be.

 

I’d reckon the OP tuned out when this became a science class.

[digitaldog]

The OP, in essence, asked two questions, one about exposure and one about adjusting for an under exposure at the software stage by using brightness and shadows.

He didn't ask that, he asked about exposure and now he can ask about adjusting brightness and altering tone if he decides he wishes to. At least one other person here found the correct definition of exposure useful so, part of my work is done.

"Mistakes are a great educator when one is honest enough to admit them and willing to learn from them". -Source Unknown

I’d reckon the OP tuned out when this became a science class.

“Most of our assumptions have outlived their uselessness“.-Marshall McLuhan

That the OP may have left due to those assumptions is moot, as I wrote, at least one other found the facts about exposure useful. Isn't that what such forums are for?

No need to answer that rhetorical question, but the questions about "Digital density" still await proof of concept. ;)

[samstevens]

Please reread the OP. He asked about exposure and then he asked a software question. Again, grade school level reading comprehension needed.

 

I notice you repeatedly get in one last zinger before you declare that we should get back on topic or that there’s no need to respond. That’s color expert narcissism, I reckon.

[digitaldog]

Please reread the OP. He asked about exposure and then he asked a software question.

 

The OP, nor anyone has specified what data or software they are speaking of. It's absolutely necessary! The bit about:

• Exposure raises the level of every pixel in the image
  
• Highlight adjusts the level of the top third (approximately) of the pixels
  
• Shadow adjusts the level of the lower third of the pixels
  
• Midrange adjusts the middle third of the curve
  
• Black adjusts the threshhold at the bottom of the curve below which every pixel is considered black.
  

... Is absolutely incorrect depending upon the software used or the kinds of data being edited. ACR/LR treat data quite differently than Photoshop with gamma corrected rendered data. Photoshop itself cannot even process raw linear data. That's a fact. We can go there, based on specific text from the Adobe engineers if anyone wants to (no matter what any sliders are called.)

 

Meanwhile, what exposure is and isn't should be clear to some here with a grade school level reading comprehension.

 

IF the OP comes back and asks about adjusting brightness (which can be done with many differing products and kinds of data), and tells us if he's shooting raw or not, and what software he's using, then his answers can (hopefully by some) be correctly answered. OR if anyone else who's actually interested in how this stuff actually works with specified software and data. Regurgitating misinformation and generalizations isn't helpful nor necessary, and experts, color or otherwise should refuse to do so.

[samstevens]

[KoolM1]

Content deleted

Spammer, using embedded links.

Edited January 28, 2021 by William Michael

[william_frucht]

KoolM1, your original question seems to be what to do if your images are underexposed. And I'm guessing from the lack of detail you've provided that you're something of a beginner at this. Let me answer you from the viewpoint of someone who's closer to a beginner level than Andrew Rodney's level.

 

First, correct exposure happens in the camera. You need to know how your camera's basic controls work: aperture, shutter speed, ISO. You may want to take your camera off automatic mode and shoot manually until you have a sense of how these functions interact, and how they relate to movement and depth of field. You may want to invest in a good tripod--make sure it's both light enough to carry around and sturdy enough to support whatever camera you're using. Back when everyone who wanted to learn photography seriously passed through a stage of shooting Kodak Tri-X 400 with a fully manual camera (because that's all there was) and developing it themselves, we were told "expose for the shadows, develop for the highlights." This is still good advice if you're shooting b/w film, but with many digital cameras it can lead to blown-out highlights--less so than it used to, though, as cameras' dynamic range improves. There are ways to bracket exposures and merge them; I won't get into that here. In brief, you can do a lot with a properly exposed image. With a poorly exposed image, you can do much less, and you may never get it to look good.

 

Your post-processing software offers you a lot of different controls, many of which can help if used gently. Raising the "exposure" (whatever that actually does) can help some. Bumping up the brightness of the shadows may help some. There's a noise control function that you'll want to use, because any brightening of an image can increase the noise level. Again, "gently" is key: a little bit of adjustment goes a long way, and unless you know what you're doing, if you find yourself making large adjustments you may be making things worse rather than better. The poster who suggested you use curves was offering good advice: at a certain point, you may find yourself doing almost all your tonal adjustments in curves, because it's the most precise way to control tonality. In Photoshop, which I use along with Camera Raw, you can make all of these adjustments on selected parts of the image, so that different areas have not only different brightness but different contrast levels that you can set just for that part of the image. But note that Ansel Adams's advice from a half-century ago still applies: "Get the information onto the negative." If there's no information in your shadows, no amount of brightening will put it there. All you'll get is more noise. So, to update Adams, get the information onto your sensor. If it's there, you can work with it in any number of ways. If it's not there, you may need to throw away the image and work on a different one.

Edited January 28, 2021 by William Michael

[conrad_hoffman]

I use what Paint Shop Pro calls the histogram adjustment for most everything related to contrast and brightness.

[Ed_Ingold]

Ansel Adams's advice from a half-century ago still applies: "Get the information onto the negative." If there's no information in your shadows, no amount of brightening will put it there.

That's certainly true for film, which has an S-shaped characteristic curve. However digital sensors are intrinsically linear, with an S curve imposed during processing because it makes more photographic sense. That means there's a lot of detail in shadow areas that can be recovered by increasing the ISO (gain), by zone (shadows) or globally (i.e., "exposure").

 

Overexposure is far less forgiving. Once the sensor is saturated, further exposure has no effect. It is an hard cutoff. For a "properly" exposed image, the cutoff is roughly 4 stops above the mid-level part of the image. Used more frequently for video, Log gamma profiles take advantage of the basic linearity of the sensor by imposing a broad flattening on the upper end of curve, and lowering the overall exposure by 2-4 stops, making overexposure unlikely, even under extreme circumstances (e.g., in streaming sunlight or stage lighting). RAW video codecs employ a similar strategy.

 

Digital photography is much like using reversal film. The rule is "Mind the highlights and let the shadows fall where they may." The good news is, digital images really have shadow detail.

[william_frucht]

Ed, I agree, and as I noted, exposing for the shadows with a digital camera can give you blown-out highlights. It's also true that good cameras today, which claim 14 stops of dynamic range, capture a lot of shadow detail that older cameras may not. I still think Adams's advice is worth heeding: get the information onto the sensor--even if, as you point out, we now have to worry more about the other end of the histogram. Point taken, and truth be told, I'm still working mostly with film.

[digitaldog]

To quote Adams (New York Graphic Society edition, fifth printing, pages 15/16): “The photographer who wishes to work toward a predetermined result must visualize the tonalities in which he wants certain important parts of the subject to be represented, and plan his exposure and subsequent treatment accordingly.”

 

“You don’t take a photograph, you make it.” – Ansel Adams

[digitaldog]

Yes. Rational assumptions are made all the time.

William posted an answer that seems likely to be in the OP’s wheelhouse. His was a reasonable approach.

Rational and a bit wrong depending on the assumptions. Ed corrected him and I'll go farther since this is a peer reviewed forum on a subject that's technical.

First, correct exposure happens in the camera. You need to know how your camera's basic controls work: aperture, shutter speed, ISO.

 

ISO isn't an attribute of exposure, we've been over what is. ISO is part of metering which a photographer should understand and not assume. An ISO setting may provide an exposure recommendation the photographer who doesn't assume, may wish to ignore. Case in point, these two captures have identical exposure: aperture and shutter, the identical amount of light hit the sensor. One is ISO 100, the other ISO 800 and one has far, far more noise than the other. The higher ISO has LESS noise, because the photographer didn't assume and understands how to expose raw data optimally. Before going further, one should not treat exposure for a JPEG and a raw the same; different data as I tried to explain, different ways and objectives to expose hence those of you shooting raw+JPEG, one of those two captures is suffering increased noise from suboptimal exposure. Anyway, two exposures that are identical, differing ISO, differing degree of noise:

 

http://digitaldog.net/files/CU_ISO100-800.jpg

 

http://digitaldog.net/files/100vs800iso.jpg

 

HENCE, when the OP tells us if he's shooting raw or JPEG (or dog forbid, both at the same time), then some of us can stop assuming and provide him advise based on how this stuff actually works. ;)

 

Ed, I agree, and as I noted, exposing for the shadows with a digital camera can give you blown-out highlights.

No, over exposing highlights blows out highlights. You view a raw Histogram to see if this is the case or not, as outlined pages ago in a number of URLs. There is nothing wrong per se with blowing out highlights IF that's your goal (shoot someone that needs to be stripped on a white bkgnd, you may want to do so, or just for a subjective look). One needs to understand how to expose and control what gets clipped and what doesn't. Photographers have been doing this for well over 120 years !

 

Ed is spot on, with digital, the raw data is linear and half of all that data is contained in the first stop of highlights so one treats it like a transparency; expose for the highlights, develop for the highlights too. Development differs on the raw converter. Assumptions as to the converter the OP is using exist, we don't even know if he is capturing and processing raw data or camera processed JPEGs.

Edited December 26, 2020 by digitaldog

[samstevens]

and I'll go farther

Of that, there is no doubt.

 

I’ll let this statement of yours pass as a perfect exception to Van Gogh’s thought.

[digitaldog]

Of that, there is no doubt.

 

I’ll let this statement of yours pass as a perfect exception to Van Gogh’s thought.

Something you've failed in doing here:

In teaching others we teach ourselves.

"Don't just learn the tricks of the trade. Learn the trade." -James Bennis

Edited December 26, 2020 by digitaldog

[Ed_Ingold]

Adam's strategy was to expose for the shadows and manage highlights by pulling development. That takes advantage of the peculiarities of film. Digital image is a different animal, with different advantages and quirks. Imaging software has similarities and unique features, so ad infinitum. You learn to use them to their best advantage, much like a second language, first the grammar by book, then the idioms by experience. I'm learning to cuss in digital ;)

[samstevens]

It’s good to learn about the technical aspects but I don’t ever want that to become an end in itself. So, I have mostly found a balance that works for me which tends to include more looking at great photos of the past and thinking about aesthetics than scientific formula, more trying to find personal inspiration and outlet through photography always with an eye toward the “quality” that will best express what is moving me in a picture. With digital, I find more forgiveness in shadows (more ability to recover) than in highlights, so I tend (with exceptions) to expose for the highlights. As I said to begin with in this thread, because it’s something the OP actually asked about, to adjust for a less than optimal exposure of a shot I think still has possibilities, I find curves and levels adjustments more helpful than brightness and shadows adjustments. As these are public forums to which all are invited to participate, there will be all degrees of academic achievement reached and all degrees of actual photo-making achieved. It’s up to the OP what info and how that info is presented will be most useful. Any good student knows that double checking information is a sound learning tool in order to avoid unreliable sources. A good student will also learn to develop a sense of what’s necessary to dig deeper into and what’s not, to get to the desired goal.

[digitaldog]

It’s good to learn about the technical aspects but I don’t ever want that to become an end in itself.

Amateur and hobbyists can individually decide to learn whatever they desire in terms of photography.

Not all of us fall into that group. "Professionalism is knowing how to do it, when to do it, and doing it." -Frank Tyger

As I said to begin with in this thread, because it’s something the OP actually asked about, to adjust for a less than optimal exposure of a shot I think still has possibilities, I find curves and levels adjustments more helpful than brightness and shadows adjustments.

The OP's question made clear to some here, he needed to better understand and explain his exposure goals since he lumped exposure into post processing and the two are not even remotely the same.

As these are public forums to which all are invited to participate, there will be all degrees of academic achievement reached and all degrees of actual photo-making achieved. It’s up to the OP what info and how that info is presented will be most useful.

Its up to more than the OP, it's up to anyone reading the forum posts, those posting or simply lurking.

A good student will also learn to develop a sense of what’s necessary to dig deeper into and what’s not, to get to the desired goal.

With a good teacher who provides facts, not misinformation. Good students know what they don't know, not what they think they should know about.

"Learning is not attained by chance. It must be sought for with ardor and attended to with diligence. "-Abigail Adams

[samstevens]

I'll end my participation in this thread, first, by noting that the OP did come back and seemed at least to me to communicate his priorities in asking the original question and, second, for me to say clearly and distinctly that Digital Dog is always right and should not be questioned or disagreed with and, third, that I could give a rat's patoot about someone being a professional and, fourth, that there are plenty of photographers who are artists or otherwise who don't fit the categories of professional, amateur, or hobbyist, whether those categories are invoked judgmentally or more matter-of-factly though in an erroneously limiting capacity.

 

ceci n'est pas un train épave

[digitaldog]

I'll end my participation in this thread...

Fine, it's your right to do so.

... second, for me to say clearly and distinctly that Digital Dog is always right and should not be questioned or disagreed with...

Another assumption.

"Mistakes are a great educator when one is honest enough to admit them and willing to learn from them". -Source Unknown

... third, that I could give a rat's patoot about someone being a professional ...

"A professional is someone who can do his best work when he doesn't feel like it."-Alistair Cooke