Some of you may or may not have heard of a technique in photography known as “Exposure Bracketing.” This is when you tell your camera you want to take multiple versions of the same image using different exposures. With this technique, you’ll produce one image with a lower exposure (i.e. a darker image), one image with a middle exposure, and one image with a higher exposure (i.e. a brighter image). Different cameras have different capabilities, but here is an example.
With my Canon 7D, I can access the “Exposure Comp./AEB Setting” (AEB stands for Auto Exposure Bracketing) via the main menu and use my main dial to set a lower exposure and an upper exposure value. By default, there is also a middle exposure value. So, in the end, this setting will produce three different exposure values of the same image (assuming I am set up on a tri-pod – you still have to press the shutter button three times to create each exposure bracketed image). Some cameras allow you to take more than three exposure bracketed images.
All this is important because exposure bracketed images allow you to blend the three exposures together during the image editing process to create an “HDR,” or High Dynamic Range, Image. By blending these three photos with different exposure values together, you get the best lighting from all the photos. For example, you can get the details from a bright sky and a dimly lit foreground at the same time.
Once you have taken your exposure bracketed images with your camera and imported them into your computer, you have to perform something called an “HDR Merge” to begin to take full advantage of this feature. This term refers to simply stacking your exposure bracketed images on top of one another, and then editing the stacked photos together to bring out the best qualities in each. In Darktable, there’s an easy way to accomplish this task.
Start by opening the Darktable app on your computer (I opened Darktable using the search bar in Windows, shown in the image above – though many of you can simply use the Desktop shortcut).
Navigate to the Lighttable tab (red arrow in the image above) if you aren’t taken there by default. This is where you can import and browse through images you’ve taken with your camera.
On the left side of this window, navigate over to the “Import” dropdown section (blue arrow in the image above) and click the arrow to expand it. You’ll see some options for importing your images – choose “Folder” to import an entire folder of images (yellow arrow in the image above), or choose “Image” to only import selected images from a folder (you can select multiple images using the shift or ctrl key when you click on the images you want to import – I go over importing in more detail in my Fundamentals of Photo Editing in Darktable course on Udemy).
In my case, I’ll use the “Folder” option and import all the images inside my Aug 11 2020 folder (red arrow in the image above). I’ll single-click on that folder and click the “Open” button to import those images (blue arrow).
Once my images are imported, I can scroll through them using my mouse wheel until I find the images I’d like to use for my HDR merge. In my case, I have my camera set up to take a RAW version of a photo (which creates a .CR2 file – blue arrow in the image above) and a JPEG version of the photo (yellow arrow) – so each photo taken by my camera is a duplicate. Some of you may ONLY have a RAW image, or ONLY have a JPEG image. Either way, this technique will work for you.
In my case, I’ll hover my mouse over the first image I want to use in the HDR merge and click on it (red arrow in the image above). This will select the image. (I went with the RAW version – or the CR2 file – of my photo rather than the JPEG version).
Then, I’ll hold the ctrl key and click on the lower exposure photo (i.e. the darker photo – red arrow in the image above).
Finally, while still holding the ctrl key, I’ll click on the higher exposure photo (i.e. the brighter photo – blue arrow in the image above). I should now have three photos selected (the other two selected photos are denoted by the red arrow in the image above) – each one being the same photo (I did indeed take this photo on a tripod) but with different exposure values.
Once all my images from the exposure bracketing have been selected, I’ll navigate over to the right side of the Lighttable window to the dropdown labeled “selected images” (yellow arrow) and click to expand this dropdown. Then, I’ll click the button titled “Create HDR” (red arrow in the image above – note: this button will only display if you have multiple images selected. You’ll also notice, when you hover your mouse over it, that the button says it will “Create a high dynamic range image from selected shots.”).
Once you click the Create HDR button, Darktable will get to work merging the images together (in the bottom left corner of Darktable it will say “merging 3 images” – blue arrow in the image above – or however many images you are merging).
Once the merging is complete, you should now see a new image (red arrow in the image above) created at the beginning of the three images you selected for merging. The image may appear dark and desaturated at first, though you can fix this using the Darkroom tab. When you click on the image and hover your mouse over it, you’ll see the image is now a “.DNG” file. DNG stands for “Digital Negative” and is the standard filetype used when creating an HDR merge.
When you double-click on the DNG image, it will open in the Darkroom tab (highlighted in yellow in the image above) where you can edit it. Because the photo is three different photos stacked on top of each other, the editing you perform using the modules in Darktable will create different results than what you may be used to when only editing a single photo.
That’s it for this tutorial! If you want to learn more about Darktable, check out my Fundamentals of Photo Editing in Darktable course on Udemy where I cover the basics of how to use the program, as well as the best modules for editing or processing your RAW images.