HDR Efex Pro merge tools

How to use the HDR Efex Pro merge tools

Like other HDR tools, HDR Efex Pro 2 is designed to work with a sequence of bracketed exposures which cover a wider dynamic range than a single image could record. This means you need to pay special attention to the HDR Efex Pro merge tools. You’ll see these whenever you open a series of images, either with the standalone HDR Efex Pro 2 app or by invoking it from within a program like Aperture.

So here’s a guide to these tools, what they do and how they work. Not everything is quite as it seems, but it is relatively straightforward once you see what’s going on, and you may find that once you arrive at settings that suit the way you shoot, you don’t need to change them in future.

01 Preview brightness

HDR Efex Pro merge tools

Here’s the first thing you need to know! The image preview has a brightness slider underneath that appears to show the tonal width of the image you’re looking at in wider tonal scale that you might imagine represents its full dynamic range.

This is not the case. This slider is simply there to adjust the brightness of the preview and to help you make other adjustments more easily. It has no effect at all on the merged image, so you do not use this to try to influence the overall exposure.

02 The loupe tool

HDR Efex Pro merge tools

Now to make the most of the HDR Efex Pro merge tools, you’ll need to be able to zoom in on the image detail, and for this you need the loupe panel. To show this, click the magnifying glass icon (circled in red) in the bottom right corner of the preview image. You can see the loupe panel just to the left.

If you used a tripod for your HDR sequence, you probably won’t have any trouble with the image alignment. I didn’t use a tripod for these shots – I used the camera in auto-exposure bracketing mode for speed and convenience, so although the shots were taken in quick succession, I’m expecting to see some slight alignment variations between them, and this does show up in the loupe panel.

You’ll need to choose the area you examine quite carefully. Choose a static object that won’t have moved between exposures. Don’t use things like leaves or pedestrians… that’s a ‘ghosting’ issue which is coming up next.

03 Alignment

HDR Efex Pro merge tools

To fix any shift in the camera position, I can click the Alignment button, circled here on the right. HDR Efex Pro has alignment algorithms which can automatically line up the frames, and for small variations like this it works perfectly. The loupe panel shows that the detail now looks more natural.

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