Tone mapping

Transform tricky shots with tone mapping

Sometimes you get scenes where the brightness range is so great you just can’t bring out all the different tones in the picture. This is lighting problem, not a dynamic range problem. Even if your camera has the dynamic range to capture all the tones in the scene, there’s no way of showing them all. You can make the brighter parts of the picture look wonderful but the shadows are left looking murky, or you can open up the shadows and leave the bright areas looking wishy washy.

There are regular image-editing tools that can fix this up to a point, such as the Shadow/Highlight command in Photoshop, but these typically leave nasty ‘glow’ effects. The Highlights and Shadows sliders in Lightroom and Adobe Camera Raw can do an OK job, but you can be left with flat-looking contrast and ugly edge effects around object outlines.

But there is another way. This may not be an HDR problem, but HDR software may have the answer – in particular, its ability to ‘tone map’ a very wide brightness range into a regular, viewable image.

Tone mapping is just the first part of the HDR process, but it may be all you need. And of all the programs I’ve tried so far, the Tone Mapping Persona in Serif Affinity Photo is the one that’s impressed me most. That’s what I’m using here, but it’s worth trying any other HDR tool you can get your hands on. You don’t need to start from a bracketed exposure series, either. Affinity Photo can ‘tone map’ a single RAW file just as happily as a merged exposure series, and other HDR software is the same. The trick is to find a preset effect, or a set of manual adjustments that looks natural.

So here’s the start shot. It’s a spectacular interior shot with a super-wideangle lens, but although the upper levels of this building are well exposed, the lower levels are in shadow. I’ve already tried fixing this up in Lightroom and I can only get halfway to the result I want.

Tone mapping

But here’s the same image, opened as a single RAW file in the Affinity Photo Tone Mapping Persona, with a series of annotations to show what’s going on.

Tone mapping

01: This status bar at the top shows that Affinity Photo has opened the RAW file in its ‘unbounded’ 32-bit colour space. HDR applications typically work in 32 bits – this is a far wider brightness range than the screen can display, but the software can call on this extra data to create its tone mapped images.

02: These are Affinity Photo’s HDR presets. Other programs, like MacPhun Aurora HDR and Nik HDR Efex Pro have their own. When you select a preset, the software ‘tone maps’ the 32-bit data into a visible image. I’ve chosen Affinity Photo’s ‘Dramatic’ preset, and it certainly is dramatic. What impresses me most about this program is the way it compresses this super-wide tonal range into an image that still has clarity, contrast and ‘bite’, and not a hint of those typical HDR ‘glow’ effects.

03: These are the manual HDR adjustment tools. Pretty much all HDR software works in the same way – you choose a preset, then you jiggle the controls to your taste. I’m not going to mess with these (a) because the Dramatic preset has got the look I want straight off and (b) because they’re pretty complex to mess with. You can spend a lot of time trying to improve HDR presets in programs like these and end up back where you started.

So here’s the finished image. I’m really pleased with this because it’s captured the rich beautiful lighting of this interior with the usual HDR ‘look’. So the next time you’re struggling with a scene with an extreme tonal range you want to balance up, try tone mapping it with HDR software.

Tone mapping

One thought on “Transform tricky shots with tone mapping

  1. This is the clearest, most helpful explanation of tone mapping that I’ve ever seen, particularly the sentence saying that it is the first step in doing HDR. The part about AF’s color space also helped me understand what’s going on.

    Thank you!

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