What Does Dehaze Do in Lightroom (And How to Use It)
What Does Dehaze Do in Lightroom & How to Use It
As recently as 2014, Adobe‘s Lightroom lacked a dedicated tool for dealing with atmospheric haze in photos. Photographers had to rely on a combination of Contrast, Clarity, and local adjustments to try to cut through the fog. Many of these techniques were fiddly, inconsistent, and resulted in unwanted artifacts.
Enter the Dehaze tool, introduced in Lightroom CC 2015. With one slider, Dehaze promised to cut through the gloom and reveal the hidden details in our photos. But how exactly does it work, and how can you get the most out of this tool? In this article, we‘ll dive deep into the science behind Dehaze, dissect how it compares to other tools, and showcase a variety of examples to illustrate its power.
What Is Atmospheric Haze?
Before we explore the Dehaze tool, we need to understand the common culprit it‘s designed to combat: atmospheric haze.
Atmospheric haze occurs when light is scattered by tiny particles in the air such as dust, smoke, or moisture droplets. The smaller the particles, the more bluish the haze appears. This is because shorter (blue) wavelengths of light are scattered more strongly than longer (red) ones – a phenomenon called Rayleigh scattering.
Haze is a common issue in landscape and outdoor photography. According to a study by the World Meteorological Organization, haze and fog occur in nearly 10% of all daylight hours globally (1). The most haze-prone regions are humid areas like forests and coastlines, as well as urbanized and polluted areas.
The further you shoot through a layer of haze, the more pronounced its effects will be. It acts like a milky filter over the scene, reducing contrast, desaturating colors (especially blues), and obscuring distant details. In severe cases, it can completely wash out backgrounds and make photos look flat and lifeless.
How Does Dehaze Work?
At its core, Dehaze is a contrast-enhancing algorithm that targets the midtones of the image. Adobe has not disclosed the exact math behind Dehaze, but independent research (2) and Lightroom experts have largely deduced how it works.
Dehaze starts by estimating the amount and color of the haze in the image. It looks for regions with low contrast and color saturation, especially in the upper half of the frame where atmospheric haze tends to accumulate. It then generates a "haze map" – a grayscale representation of where the haze is strongest.
Next, Dehaze applies a custom contrast curve to the midtones of the image based on this haze map. The curve boosts contrast substantially in the lighter midtones (which are most afflicted by haze) while leaving the shadows and highlights largely untouched. Simultaneously, it bumps up color saturation in the affected regions to counteract the desaturating effect of haze.
The end result is that haze is selectively removed where it‘s most prevalent, while preserving contrast and color in the rest of the scene. Here‘s a quick before/after to illustrate:
[Before/After Dehaze example showing reduction in haze]Notice how the distant mountains and sky are much clearer after applying Dehaze, while the foreground rocks are minimally affected. This is Dehaze‘s key advantage – it can intelligently target just the hazy regions.
Dehaze vs. Clarity and Contrast
To appreciate what makes Dehaze unique, we need to compare it to two other contrast tools in Lightroom: Clarity and Contrast.
The Contrast slider is a blunt instrument. It indiscriminately boosts contrast across the entire tonal range by brightening the highlights and darkening the shadows equally. While this does cut through haze to some degree, it can also result in clipped highlights, crushed shadows, and an artificial-looking result. Here‘s an example of Contrast vs. Dehaze:
[Comparison of Contrast vs. Dehaze, showing clipping from Contrast]The Clarity tool is more sophisticated. It boosts midtone contrast while largely preserving the shadows and highlights. Clarity also has a large radius, meaning it affects larger-scale contrast across the image. This can help with haze to some extent.
However, Clarity is not as targeted as Dehaze. It boosts all midtones equally and doesn‘t take into account the location or color of the haze. It also tends to introduce a "crunchy" look with oversharpening halos around edges. Here‘s a comparison of Clarity vs. Dehaze:
[Comparison of Clarity vs. Dehaze showing oversharpening from Clarity]In contrast (pun intended), Dehaze is like a "smart Clarity". It focuses its contrast boost on the lighter midtones and regions most impacted by haze. This allows it to eliminate haze while preserving natural contrast elsewhere in the scene. Dehaze also avoids the oversharpening artifacts that Clarity often produces.
To put some numbers to it: Adobe has stated that Dehaze can boost midtone contrast by up to 35% in the haziest regions (3). In my experience, Dehaze also increases color saturation by 10-20% where it‘s applied. These localized enhancements add up to a much more targeted haze reduction than Contrast or Clarity can achieve.
When and How to Use Dehaze
Now that we know how Dehaze works, let‘s explore some situations where it excels and discuss best practices for using it effectively.
Landscape and Outdoor Photography:
Dehaze is most impactful for landscape photos shot in hazy or foggy conditions, especially those with distant backgrounds like mountains or cityscapes. It‘s also useful for scenes with subtle haze that you may not have noticed while shooting.
A little goes a long way with Dehaze. I recommend starting with a value of +10 to +20 and gradually increasing it until the haze clears. Values above +50 often look unnatural. Here are some examples with specific Dehaze settings:
[Example 1: subtle haze, Dehaze +15] [Example 2: moderate haze, Dehaze +30] [Example 3: strong haze, Dehaze +45]Keep an eye on your histogram as you increase Dehaze. You want to see the mountain of the histogram shift slightly to the right, indicating a global contrast boost. But if it starts flattening out or clipping at either end, you‘ve gone too far.
Nighttime and Astro Photos:
Dehaze is surprisingly effective for night photos plagued by light pollution. The orange glow from artificial lights can wash out the sky and make stars and the Milky Way harder to see.
Applying Dehaze (+30 to +50) darkens the sky and makes the stars pop. Pay attention to color shifts though – Dehaze can sometimes introduce a purple or magenta cast into night skies. If this happens, use the White Balance selector in the sky to neutralize it.
Portraits and People:
While Dehaze is primarily a landscape tool, it can be helpful for environmental portraits shot in hazy or backlit conditions. The key is to apply it selectively using a local adjustment brush.
Paint over the background with an Adjustment Brush, then bump up Dehaze to taste (usually +15 to +30). This will clear haze from the environment while leaving your subject unaffected. Here‘s an example:
[Example of subject with dehazed background using brush]Black and White Photos:
Dehaze is a secret weapon for black and white conversions. It adds midtone contrast and grit without blowing out highlights or crushing shadows like the Contrast slider often does.
For most B&W photos, I suggest a Dehaze value between +30 to +50. This adds a pleasing amount of contrast and tonal separation. You can go as high as +70 for a grittier, documentary-style look.
[B&W example with Dehaze]Workflow Tips:
- Apply Dehaze early in your editing process, just after adjusting White Balance and Exposure. This allows subsequent edits build off the dehazed version.
- If the effect looks too strong, try backing off Dehaze and bumping up Contrast or Clarity instead. The combination often looks more natural.
- Dehaze can sometimes make edges look oversharpened. Follow it with a light amount of Noise Reduction (10-20 Luminance) to smooth things out.
- For ultimate control, use the Graduated/Radial filters and Adjustment Brush to apply Dehaze selectively. This is great for optimizing different regions independently.
- If Dehaze washes out color in part of the image, use the HSL sliders to bring back saturation for specific hues. The Saturation slider in the Presence (Basic) panel is also helpful.
- Zoom into a region affected by haze as you adjust the slider. This makes it easier to see the effect and find the right amount.
When NOT to Use Dehaze
As great as Dehaze is, it‘s not a cure-all. There are some situations where it can actually do more harm than good:
- Scenes with little to no haze. If your photo is already clear and contrasty, Dehaze will make it look artificial.
- Intentional haze or fog. Sometimes that misty look is exactly what you want – don‘t destroy the mood by overusing Dehaze!
- Photos with lots of Noise. Dehaze can exaggerate noise, especially in underexposed regions. Denoise thoroughly before applying Dehaze.
- Silky waterfalls or moving subjects. Since Dehaze enhances edge contrast, it can introduce ugly artifacts around soft, moving subjects.
- Photos with large clipped highlights. Dehaze will only exacerbate the clipping, leading to an HDR look. Recover the highlights as much as possible before applying Dehaze.
Creative Uses for Dehaze
Despite its name, Dehaze isn‘t just for removing haze. With some creative experimentation, you can use this versatile tool to stylize your photos in other ways:
Vintage Haze Effect:
Try setting Dehaze to a negative value (-20 to -50) to introduce a dreamy, vintage-inspired haze to your photos. This can be especially effective for fashion and portrait photography.
Gritty, Contrasty Look:
For an edgy, documentary-style look, push Dehaze to the max (+70 to +100). This will create a harsh, gritty contrast that suits certain portraits and street photos. Pair it with a slight vignette for extra drama.
Cinematic Depth:
You can use Dehaze to enhance the sense of depth and layering in your images. Try using a Graduated Filter to apply strong Dehaze (+50 or higher) to the background while leaving the foreground untouched. This mimics the look of cinematic "deep focus" shots.
Color Grading:
Believe it or not, Dehaze can even be used for creative color effects. Try setting Dehaze to a high positive value, then use the HSL/Color sliders to drastically shift the hues. The result is an edgy, surreal look that works great for abstracts and certain landscapes.
Closing Thoughts
Hopefully this deep dive has given you a newfound appreciation for the power and versatility of the Dehaze tool. While it was primarily designed for removing atmospheric haze, we‘ve seen that its contrast-enhancing magic can be applied to a variety of photographic situations.
From subtle haze reduction to gritty black and whites to dreamy vintage effects, Dehaze is a swiss army knife that every Lightroom user should have in their toolbox. Like all editing tools, it requires a delicate touch and a discerning eye. But with practice and experimentation, you‘ll be able to wield Dehaze with confidence and take your photos to new heights.
The next time you‘re confronted with a dull, flat, or hazy image, don‘t give up hope. Dehaze to the rescue!
References:
(1) World Meteorological Organization: https://public.wmo.int/en/bulletin/long-neglected-haze-clearing
(2) Letizia, F. et al. (2015) "A haze removal tool derived using the dark channel prior technique", Proceedings of SPIE, Vol. 9443
(3) Adobe Product Support: https://helpx.adobe.com/lightroom-classic/how-to/lightroom-dehaze.html