#1265. A few thoughts on contrast

By pascaljappy | How-To

Feb 02

Much of what we do in photography to create a visual style comes down to contrast management. Yet we rarely give it the prominence it deserves in our thought process.

Bridge over the river Thames in London photographed in soft lightling in black and white
Soft lighting, sharp detail
 

Contrast needs to be defined between two areas. The contrast between two pixels refers to their difference in luminance or in colour. The term Contrast in a whole photograph is usually used to refer to the depth of the dominant shadow areas and the lightness of the dominant highlight areas.

It is easy to recognise in a histogram. When all the tones are bunched up together (whether in the shadows, or in the midtones, or in the highlights, it doesn’t matter) you have a low contrast image. When most of the tones are in the highlights and in the shadows, with little in between, you have a high contrast photograph.

The photo above would generally be considered to be low-ish contrast, while the one below is high-ish contrast.

A high contrast black and white photograph of a sunlit dock.
Deep shadows, bright highlights.
 

The important distinction between the two ideas (pixels vs whole frame) is the scale on which contrast is being considered. In one case, we can measure the luminance difference between two neighbouring pixels (for instance to measure the MTF curve of a lens). In the other we are judging the tonal range of a whole image.

There are many stages in between, and most of the tools in our editing software are based on those.

In Adobe Lightroom, for instance, you have the Constrast slider, the Tone Curve editor, and the Texture, Clarity and Dehaze sliders. All of these alter contrast at various scales ranging from a few pixels (Texture) to the whole frame (Contrast slider, Tone Curve editor). Oh, and the sharpening tool, at the pixel level!

An aerial view of clouds from an airliner, exposed for the highlights.
High contrast flight
 

Sadly, none of those tools give us complete control over the process. They apply recipes that include local contrast enhancement (of various scale) along with other proprietary tone manipulations (at least, I imagine so).

Other software actually lets you define the amount of contrast you want to add or eliminate from an area of the photograph, as well as the radius of the brush you are applying, and whether to apply to the shadows midtones or highlights. That is nice. You can of course replicate that through the layers of Lightroom. I’m not dissing Adobe, only highlighting different approaches to what constitutes the topic of this post: contrast can be applied more or less locally or globally.

While this might seem like stating the obvious, the feature is not being used nearly enough. And my guess is that the obscure labelling of the various tools that offer the option is partly responsible for that.

Blue-green forest (low colour contrast)
 

Before continuing to how to use that contrast, a quick word about colour.

A colour photograph contains luminance information and colour information. You can therefore apply contrast to either or both and it is easy to mix up the two concepts. Colour contrast refers to the nature of the hues present in the image and where they fall (on the colour wheel, for example) relative to one another.

In the photograph above, you see moderate (global) luminance contrast and low colour contrast, because all the hues are blue or green. In the photograph below, made in the same forest but with different colour balance, you again see moderate luminance contrast but much stronger colour contrast. The colours are far more different from one another below than above, in other words.

View of a lush forest environment
Magenta-green forest (higher colour contrast)
 

Below is a low luminance contrast (all the tones in the photograph are bunched up in the mid-high zone) but high(ish) colour contrast photograph (green and orange & pink pastels).

Low contrast, high(ish) colour contrast
 

And below is a high luminance contrast (lots of highlights, lots of shadows) and high colour contrast image (orange, green and blue dominate) photograph. Particularly in the top-right corner.

Bright sunlight on a brick and glass wall creating reflections in the street.
High luminance contrast. High colour contrast
 

Altering the luminance will also alter the colour, because saturation of colours is highest in the midtones. So lifting the midtones to lighter tones will make the colours more pastel, for example. But we won’t cover this here. Let’s get back to contrast.

Contrast matters because it influences composition.

All humans scan a frame based on a scanpath that is both determined by our physiology and cultural background (Asian people apparently have a more circular scanpath, where Westerners have a more linear one, for example). This scanpath is interrupted by signals of various nature. Bright zones catch the eye more than dark zones. High contrast features catch the eye more than low contrast features. Faces and other emotional or survival-related patters catch the eye as well. The interplay of all those eye-catching things is what creates the composition of a photograph.

Dark negative space
 

Ever seen Sylvain Tesson’s photograph of a snow leopard hiding in plain sight? It’s hard to spot because of its “low contrast” (a.k.a. camouflage) compared to the rest of the scenery. But once you’ve seen it, that’s all you see, the face is mesmerizing. You can no longer unsee it and revert to the initial state of discovery.

That’s just one example of how composition works. And the photograph above is almost the opposite. There is nothing noteworthy there, no leopard, not even a bunny wabbit, but the use of contrast has increased the visual prominence of the natural features of that dried grass and created a sort of rhythm, with “holes” (dark negative space) in it.

Now, equally hidden in plain sight is composition’s little secret: a photograph, however elaborate, must be easy to read. That’s why so many of us just plonk a subject in the middle (or rule-of-thirdly) of the frame with a background that’s blurred out of existence by a fast lens. That’s an easy photograph to read, often a beautiful portrait for example.

 

The trick for readability is to know how many layers of different contrasts to apply to a photograph.

In other words, you need to know where you wish to direct the attention. You must make the decision. What do you want to show, and what do you want to hide. Add luminosity and contrast to the former, remove from the latter.

And this can be done with any of the local contrast tools mentioned above, with different visual results.

In the image above, a lot is hidden in the shadow.

In the image below, I have reduced the highlights and clarity of the light areas and done the opposite in the shadows.

A lot more information is present in the second, but is that what you want? What is your eye drawn to in both? Which do you prefer? There is no right or wrong answer, only good and bad combinations of intention and execution.

Here, you do not scan the perimeter as much
 

In this example, I kinda like both. But if I added much more clarity everywhere in the frame, it would become grating. Hey, what is a grate, if not a rectangular frame with scores of small high-contrast (for cheese or skin) areas? πŸ˜‰

You need to be deliberate with where you apply contrast and where you don’t.

The reason why landscape photographers love to shoot when the sun is below the horizon is not really because of the blue, pink or golden light. You can dial in a lot of that in post. But landscape photography is a high-detail style. And those times of day provide uniform, low contrast, light. What you get is a low global contrast image, with local contrast that guides the eye to the various features of the landscape and provides info on things like texture. The eye can spend a lot of time roaming the image, lapping up the detail. And if composition is good, it does so in the order inspired by the author. Add bright sunlight to this and, even if your camera can deal with the dynamic range, the pockets of huge contrast will dominate the scene so much that they will completely mess up the order of more subtle contrast arrangements.

Do you prefer this …
 

So how do you decide?

Well, there’s no formal method that I know of, except that it’s best to start by fixing global contrast for the general look, then alter specific areas of the frame (dodging and burning). And I would also start with large radius contrast and move on to smaller radius edit later. Properly trained visual arts students might have more to add to my purely empirical explanations. If that’s your case, please chime in πŸ™‚

The best solution to decide what your style calls for, in the absence of solid fact, is to look at photographs you like and others you don’t like, to see how contrast is applied to them. Are they high contrast, or low contrast? Do they appear ultra-sharp or softer? Grungy (typically high low-radius contrast), as above? Is the contrast the same everywhere or do some areas seem to have more than others? And so on …

… or this?
 

I personally like high-contrast scenes with large depth of field. So it’s my job to make sure this doesn’t get visually too busy, that detail in the shadow isn’t lost to a huge puddle of black, that highlights do not clip abruptly, that colours don’t turn all garish …

You may prefer very soft images in which hues can express themselves unincumbered by violent luminance trauma, but very sharp locally, for instance. Or low contrast, low sharpness, monochrome images reminiscent of the old film days.

 

Of course, and as a conclusion, gear plays a major role here.

Low dynamic-range sensors and filmstocks appear to have more global contrast. And vice versa. Remember when Leica got a spanking for creating a Monochrom with dull images? It just used a high dynamic-range sensor and preserved all possible detail for post-processing. Brilliant, but shocking to most people.

As for lenses, what they do is essentially transfer contrast from the scene to the image surface. MTF curves display the contrast transfer levels of the lens for details of increasingly small size. Lens drawing is partly defined by the relative levels of those contrast curves. Yes, there are geometric factors (distortion, swirly bokeh, compression, depth of field) and chromatic factors (mainly the scale and appearance of aberrations) at play, but some lenses are designed to resolve fine detail yet look soft, while others are nowhere near as resolved but appear very sharp when the image isn’t enlarged. And shallow depth of field translates to blurred backgrounds, which are nothing more than locally reduced contrast levels. 3D pop is just more contrast here and less there.

I know there are hundreds of more actionable how-to videos online that describe an A to Z procedure to obtain this or that look. Some I have seen involve plugins that handle dozens of layers that let you fine tune to your taste.

My approach is the exact opposite to this spray-and-pray, everything-is-possible smorgasbord of complexity. First because those tools hide the deeper understanding that sets you free, and secondly because the look that works for the guy probably won’t work for me.

I prefer to try to understand and communicate a very limited set of funamentals and encourage a far simpler, yet more empowering, experimental method. Let me know if this one works for you πŸ™‚

 

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  • jean pierre guaron says:

    Ha ha! I saw the title – I started to assemble my thoughts – I opened your post – and found you had blown me out of the water, from the very start!

    I’m so used to seeing deep shadows and heavy contrast – particularly in B&W shots – and because I print practically all my photos (well the ones I’m not chucking in the bin, anyway) I’ve found myself pulling steadily back from that approach. It seems to work online – because there, we’re dealing with screen images – projected images. Not paper ones – reflected images. Once you go to print, instead of being able to have contrast that exceeds 100%, you’re limited to a max around 90-95%. So you pull your head in, and fit the image you’re producing within the parameters of the medium you’re using.

    I still can’t stop laughing. You’ve not only done it all the way through the article, you’ve also done comparative versions and explained to your audience exactly why you’ve done it.

    Well you’ve beaten me to it twice over – because you’re younger than me, and it’s been mostly over the past two years, churning out prints during COVID, that it’s finally dawned on me. What’s the mantra ? – “wisdom comes to us too late in our lives”. Or something. Because you’ve revealed another aspect of these issues which hadn’t yet occurred to me. Many thanks for completing my education!

    Oh well, at least I’d travelled part of the journey before your article arrived. And a kick in the pants has pushed me further along the path, now!

    • pascaljappy says:

      Thanks Jean Pierre. I’m glad this was useful. And you’re right, those aspects need particular consideration when printing, which is a whole other universe of dynamic range … Thanks for reminding me πŸ™‚

    • Michael Ulm says:

      Couldn’t agree more with your comments and conundrum. Once I started printing more I felt like I was re-training my entire thought process on contrast, as well as the depth of dark/black. My toughest decisions are now related to ‘will this image be used online or in printed form?’.

      • pascaljappy says:

        Yes, I duplicate images and process them differently depending on what the final medium is going to be. Soft proof helps a bit but I wish I had a more systematic conversion from one to the other πŸ˜‰

  • It is interesting that your article deals with contrast today, Pascal. We have had nothing but cold (27F or -3C), wet, heavily overcast flat lighting for the past four days. I spent two of those days photographing birds with a D850 and an 80-400 Nikon lens and processing them at night. This combination really made for some interesting contrast. The background tones were mostly various shades of winter foliage brown and gray and black with tree roots and limbs for perches. My goal was to capture the natural beauty of the bird in this winter habitat and make my audience go WOW. And I had to do it without allowing the appearance of any post processing. If it is obvious it is wrong. I think I used every option available on Adobe PS with some assist from Topaz Noise AI, and some flying by the seat of my pants, and mostly I was pleased. One bird took ten layers. I shot at 1/500, f/5.6 and mostly 3200 ISO for two days with ice covering almost everything. My ultimate goal is to make prints, but I posted each image on FB first. I had three prints made and framed for a juried photo exhibit at the DAC gallery. When I registered them I set them on the floor leaning against the wall to be hung later. One of them sold while it was still on the floor. If you want to take a sneak peak I think you have my FB address. The point being, your article was spot on for me after a trying time with contrast over the last few days. I’m still tired, but not nearly finished.

  • jean pierre guaron says:

    While on the subject of “thoughts” – here’s one from Henry Kissinger, that might resonate here:

    “If you do not know where you are going, every road will get you nowhere”

  • Sean says:

    Hi Pascal,
    Terrific article. You have used simple language to help a reader get their head around a frustration that I’m sure bedevils some of them. I sense it would be fair to relate what you have so well explained by what Ansel Adams practiced so well. That is Adams pre-visualised what the photograph would look like before he pressed the shutter. He consciously visualised what his final image should loom like, and that I’m sure took ‘contrast/s’ into account – both before (subject and subject matter) and after crafting an image (final output). Admittedly Adams was knee-deep in the analogue world, but I’m sure he’d relish the idea of having a serious crack at digital photography. Your article and accompanying images do just that; being that ‘contrast/s’ are an essential glue in holding all the bits that go into making a compelling, meaningful and memorable image. Regards Sean

    • pascaljappy says:

      Thank you, Sean. I too believe Adams would have had a serious (and influential) crack at digital. His Zone System was the father of ETTR, and would have explained so much about dynamic range, noise, clipping, and more, topics that are today described in isolation, without an overarching theory.

      All the best, Pascal

      • Sean says:

        Well put, Pascal. I know I have a black and white eye, but sometimes colour needs to be a prime driver for crafting an image. I have this 1993 hardcover book ‘Ansel Adams in Color Hardcover’. It’s wow viewing and a good reference point, without plagiarising.

        • pascaljappy says:

          Thanks. I remember seeing that book. Big book with an orange-red bolder on the front? I never bought it, not knowing what to think about Adams in colour. Not because of any lack of quality, but because I wasn’t interested in colour, at the time. Maybe time to give it a second thought? πŸ˜‰ Cheers

          • Sean says:

            Yes, Pascal.
            Ansel Adams in Colour [With “Selected Writings on Color Photography by Ansel Adams”]. With John P.Schaefer and Andrea G.Stillman. Introduction by James L.Enyeart. Adams, Ansel.
            ISBN 10: 0821215965 / ISBN 13: 9780821215968
            Published by Boston / New York / Toronto / London, Little, Brown and Company., 1993

            I suppose what I am trying to say in regards to my previous comment is to have it as “… a good reference point, without plagiarising…” That is, the most respectful thing to do is not to copy and be a photographer you are not, but, use it as a reference to figure out what you are as a photographer when you craft your colour images.

  • Jon Maxim says:

    Hi Pascal,

    This is one of the best of your articles that I have read. Come to think of it – the best article I have read on contrast since I learned about the Zone System in the early 70s. I have not worked in B&W since I turned to digital and I think it has been detrimental to my colour work because I have forgotten the lessons I learned about contrast. The camera club to which I belong has been asking me to do a workshop on some topic and this has given me inspiration to do it on contrast. I’m sure that preparing for it will also make me improve my work as well!

    On a related topic – I notice that you often comment on how disappointed you are with how some sensors/cameras deal with the contrast and roll-off of highlights such as clouds in the sky. I am not sure that I understand what you mean and I wonder if you have written a post that illustrates your thoughts. If you have, can you point us to it? …and maybe write one if you haven’t? πŸ™‚

    Sincerely, Jon

    • pascaljappy says:

      Hi Jon, I am so happy to read this πŸ™‚ Thank you!

      Regarding highlight rollof, what I mean is that the transition from bright to pure white is often very brutal with digital cameras. You can see an example on the review of the M11, an exceptional camera: https://www.dpreview.com/sample-galleries/5740841570/leica-m11-pre-production-sample-gallery-dpreview-tv/8931900619 (photo 7). Compare this to a similar film photo (https://jacandheath.com/film-shot-into-sun/ for example) and you will notice the transition to pure white is much smoother and much more beautiful.

      I hope this is clear πŸ˜‰ Do let me know if not!

      Cheers, and thank you again for letting me know the post had been useful.
      Pascal

      • Jon Maxim says:

        Thank you Pascal. Those examples make it very clear. I almost wish I had not asked you the question because now I cannot stop noticing other examples (and suffering as much as you do :)). I wonder if some if it is due to the advice we have been given, ever since the dawn of digital, to expose to the right. ETTR may result in crushing the gradient in the highlights. ETTL maybe? πŸ™‚

        Thanks,
        Jon

        • pascaljappy says:

          Hi Jon, ETTR is indeed a dangerous ally, but since histograms tend to be conservative, you are usually OK using them for ETTR. With cameras, there is a tradeoff between avoiding noise in the shadows and avoiding clipping in the highlights. I tend to not mind a bit of noise, and to dislike clipping. So I underexpose a lot. But it’s a matter of taste and others think the opposite πŸ™‚

          All the best,
          Pascal

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