This week, I formally made the change from HDR image processing for shooting professional real estate images, to Exposure Fusion. The benefits in this change are significant enough I felt it warranted sharing. And, clients will want to know, Torben Photography never stops looking to improve.
One of the key challenges, in interior photography in particular, is balancing the brightness of windows with a darker interior. Everyone has seen pictures an all-white, blown-out, window in an otherwise nicely exposed interior picture. Viewing the same room in person, our eyes and brains can process a large dynamic range (dark room and bright exterior) of about 17 exposure values, or EV. In comparison, digital cameras can only process about 9 EV. Anything outside either end of the camera’s dynamic range simply gets captured as black, or white. Within those white and black regions all detail is lost.
HDR (High Dynamic Range) and Exposure Fusion are two solutions to this problem that do not require the use of complex lighting (e.g. flash) setups. Both processes use a series of bracketed images as input. A ‘bracket’ is a series of images taken of the same scene, using a tripod, across a range of exposures. At one end, the images are exposed so the view through the windows looks proper; but the room is very dark. At the other end, the images are exposed so the room’s interior is properly exposed; but the windows are too bright.
Given the same set of images, the two processes work very differently. HDR takes the best midtones from each image and merges them into a single, final image. Exposure Fusion looks at each individual pixel in each image, selects the best one, and then builds the final image.
HDR processing has been around for some time and become quite popular. The range of viable solutions is part of why I originally chose this technique for use at Torben Photography. Helping to minimize the use of flash photography, reducing time on-site during shoots, was a key driver.
However I struggled with my overall satisfaction. In my view, the images struggled in three areas: natural appearance, processing time, and overall clarity and sharpness.
Sharpness & Clarity
The following images are made using the same 5 input images:
The resulting differences are immediately notable. The Enfused image is brighter…without any manipulation required…than HDR. It is also crisper.
To help make the comparison easier, I zoomed in on both images (above). The flowers are noticeably brighter, with much sharper focus, as is the chandelier, artwork, and chair fabric near by.
One of the biggest challenges with HDR processing is making sure colors are realistic. HDR, in my experience, generally tends to be warmer, with richer, more saturated colors. HDR images also tend, when pushed toward extremes, to create halos around areas of high contrast. Finally, a general feel of grunginess can be noted, as if a room were suffering from smoke damage.
This next set of images is, again, from the same set of source images. Settings for Detail and Clarity are the same.
The bedspread’s yellow colorcast is emphasized in the HDR process, carried over onto the walls. The enfused image, more closely represents the room as I recall it during the shoot. It avoids colorcasting and also renders the walls more true to color.
The issue of colorcasting is evident in the next comparison. While it is hard to get exposure setting to match exactly due to different processes, the color issues can be noted in the fireplace mantle and lamp shade. With the tools I have for HDR, oranges and yellows seem to be emphasized. In comparison, the enfused image remains more true to life while also providing better detail, also noted in the lampshade, as well as the plants.
Here, I will curtail what could be a long, tedious and arduous segment. Instead, I would like to simply provide my mostly anecdotal observations.
First, the workflow process is much shorter with exposure fusion. Working with LR/Enfuse, the tool is implemented directly within Lightroom, my primary image processing tool. That means I never need to go outside Lightroom, everything is done as though it were Lightroom itself doing it. Convenient and quick…more so…because after initial configuration there are no settings to be tweaked between image sets.
In comparison, my HDR tool, Photomatix, is an external application. I am sure, using the pro version with Lightroom integration would speed things up. However most key is that HDR processing requires significant tweaking of numerous sliders for each image set. And, the processing time itself, once set, is also longer.
From a processing standpoint I find Exposure Fusion has a lot going for it. On the plus side, processing time is shorter; no settings need tweaking between image sets; batch mode lets me do the initial processing for an entire shoot, letting me do other tasks; and overall output is clearly superior in all aspects that currently matter to me most.
The battle between HDR and Exposure Enfusion is warming up. Like many ‘religious’ battles, there’s frequently no absolute right answer. I simply wanted to help educate, share what I’ve found works for me, and let you decide for yourself.
In each of the comparison cases, I did my best to provide reasonably ‘fair’ comparisons. The processes underlying the final results are completely different; I’m not sure its possible to truly create 100% identical examples.
If you have constructive observations to share, I encourage you to do so. There is always something new to be learned.