By Douglas Wade
HDR Merge was introduced in Adobe Photoshop Lightroom CC/Lightroom 6.
High Dynamic Range (HDR) has been around for some time, and at one point people were processing lots of images that took on a “grunge” look – a look that seems over-processed in my opinion. It seemed to be more gimmick-like and less realistic. However, HDR does serve a purpose.
Why use HDR? Today’s cameras are improving their dynamic range every year as sensors improve. However, no current sensors can capture the full dynamic range. That is why taking 3, 5 or 7 images a stop apart (by changing shutter speed, not aperture) of exposure and using HDR Merge can improve the overall range. For example, when shooting a sunset on a mountain range, the camera will capture a lot of sun and fewer details on the range. If you want to see those details, HDR can help.
How does it work? HDR Merge will use different parts of each image. Details in the shadows will be used from the overexposed image, and details in the highlights are used from the underexposed image. The software is making decisions on the values, and you still have some control. The software is trying to balance the shadows and highlights of a photo so that neither are being favored or ignored.
For my example, I will use three images of a sunset at Death Valley. I want the foreground and the valley and furthest range to have detail and the sky to have depth and color.
In Lightroom I will use Stacking to group similar images together (by capture time) so I get the correct images. Photo > Stacking > Auto-Stack by Capture Time…
I have six images that I can use:
Since some images look similar, like the 1st and 2nd, 3rd and 4th and 5th and 6th , I will exclude some of them from the merge. I will select three images: Image 1 (⅛ second exposure), Image 3 (½ second exposure), and Image 5 (1-second exposure).
I selected the three images and let Lightroom merge those multiple exposure-bracketed images into a single HDR image.
- Cmd/Ctrl-click the images in Lightroom to select them.
- Select Photo > Photo Merge > HDR or press Ctrl+H.
- In the HDR Merge Preview dialog, deselect the Auto Align and Auto Tone options if necessary.
- Auto Tone: Provides a good starting point for an evenly-toned merged image
- Auto Align: Is useful if the images being merged have slight movement from shot to shot. Enable this option if the images were shot using a handheld camera. Enabling this option may not be necessary if the images were shot using a tripod. I did use a tripod.
- You can preview the effects of these settings right within the dialog box.
The HDR Merge Preview dialog:
- Sometimes, after the exposure-bracketed images are merged, some areas in the HDR image may appear unnaturally semi-transparent. Select one of the following de-ghosting option in the HDR Merge Preview dialog box to correct these anomalies: None, Low, Medium, or High. Try Low deghosting first to obtain a cleanly merged image. Try higher settings if necessary.
- Low: Cures little or minor movement between frames
- Medium: Cures considerable movement between frames
- High: Cures high movement between frames
- You can preview the effect of these settings within the dialog box. If necessary, choose to view the deghost overlay.
- Click Merge to create the HDR image (.dng). Lightroom creates the image and displays it in your catalog.
Selecting High can produce more dynamic effects. The None, Low, Medium, and High are for Deghosting but it does change the overall look. Compare it to the image above. I selected None and allowed Lightroom to process the file.
After Lightroom has merged the images, it is available in the same folder as the source files. The entire Develop Module toolkit is available to edit the resulting image to your style. For the image below, it took less than one minute of editing in the Develop Module to make an image go from lacking detail to something much stronger and interesting.