Lightroom HDR merge

Lightroom HDR: how the HDR Merge tool works

HDR photography relies on capturing an extra wide brightness range in a scene, which usually means shooting a series of exposures and then merging them in software. You can get dedicated HDR applications and plug-ins for this, but some regular photo editors are adding HDR merge tools too. The Lightroom HDR merge option has been around for a while, so how does it work and how does it compare to a dedicated HDR tool?

Dedicated HDR programs like Aurora HDR 2019 can be extremely powerful and effective, but it means paying for extra software and stepping outside your regular workflow. If you use Lightroom Classic CC or Lightroom CC, however, you may not need to.

• Read more: Lightroom CC vs Lightroom Classic

Both programs have the Lightroom HDR merge option, which can take a series of exposure ‘brackets’ and align them, adjust the exposure and apply ‘deghosting’ just like a dedicated HDR tool. So how does this work, and is the Lightroom HDR merge option any good?

Step 1: Select your bracketed exposures

Lightroom HDR merge

First you need to select the bracketed exposures you want to merge. Lightroom is just as happy with RAW files as JPEGs and will be able to use the extra colour and brightness information in RAW files to give a better result (though it may be noisier than when using in-camera JPEGs). With the images selected, right-click and choose Photo Merge > HDR from the pop-up menu.

Step 2: The Lightroom HDR Merge Preview window

Lightroom HDR merge

Lightroom will display an HDR Merge Preview window showing you how your merged image will look and with a series of options and checkboxes in a panel on the right:

Auto-Align checkbox: Definitely use this if you shot your exposure brackets handheld. Lightroom will do a good job of auto-aligning the images, but it needs to be told to do this.

Auto Settings checkbox: Why not? This gives you a balanced starting point and you’ll be able to adjust the settings later if you need to.

Deghost Amount/Show Deghost overlay: This is useful if there’s been some movement in the scene between exposures – see the next step for a little more information.

Create Stack checkbox: This will stack the merged photo in the Lightroom library with the set of exposure brackets used to create it, which is pretty handy.

Step 3: Deghost settings

Lightroom HDR merge

Sometimes don’t need the Deghost option at all, but if you have pedestrians walking through the scene, leaves blowing in the breeze or, as here, ripples of water moving near the camera, the Deghost option will reduce the appearance of ‘ghosted’ object outlines from different frames. Handily, the Show Deghost overlay option shows the areas of the image that Lightroom will Deghost with a red overlay. You can change the Deghost Amount between None, Low, Medium and High and the overlay will update to show the areas identified for Deghosting.

Step 4: The merged DNG file

Lightroom HDR merge

When you hit the Merge button, Lightroom will then combine the separated images into a single, merged DNG file (this can take a little time). There are two things to notice here. First, Lightroom creates very natural-looking HDR images. You can add more obvious HDR effects later if you need to, but if you want to disguise the fact you’ve resorted to HDR rather than drawing attention to it, the default settings are a very good starting point. Second, you’ll see that Lightroom has already ‘pre-adjusted’ the DNG file to give you a balanced exposure – but also that the Shadow and Highlight adjustments will probably have been pushed a long way towards their maximum values, so you might . not have a lot of adjustment leeway left.

Step 5: Watch out for edge effects

Lightroom HDR merge

So that’s the question – is the Lightroom HDR tool any good? Well, as explained in the previous step, it does produce nice, natural-looking images, but with pre-adjustments that might not leave you much room for manoeuvre. Worse than that, you can get some nasty edge artefacts (seen here along the top edge of the cave) caused either by fault alignment or Lightroom’s sometimes crude edge masking with heavy shadow and highlight adjustments.

Step 6: Further adjustments

Lightroom HDR merge

You may not have much scope left for further shadow and highlight adjustments in your merged DNG file, but you can apply the rest of Lightroom’s global adjustment tools (White Balance, Tone Curve, Profiles etc.) and local adjustment tools (two uses of the Lightroom Radial Filter here) to finish off the effect, or just use the Lightroom HDR merge tool for your initial tone mapping and then an external editor or plug-in, like the DxO Nik Collection or Alien Skin Exposure X4.5 for the finishing touches.

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