Single Photo HDR
HDR (high dynamic range) photography is a topic that can garner immediate disdain. It’s the mango chutney or infused olive oil of photography — a way to cover mistakes during the process and provide cover in the presentation by saying “Look, I’ve got a technique!”
However, just like the overused culinary flavorings above, in the right situations HDR can be used to draw out the subtleties of an image or provide the tools to display far more information than originally available.
There are plenty of tutorials out there on HDR best practices — utilize a tripod, bracket, Aperture mode only, shoot RAW, etc. But sometimes I come across a photo after the fact and I think “Hmmm, this would have been a good HDR shot” and I only have one of the original. In these (relatively few) cases, I’ve got a fairly fool-proof workflow in Photoshop to emulate what proper shooting and preparation could have done originally. It involves taking a single image and creating copies with multiple exposures. I used this workflow recently with one of my digital shots from the Rome trip in October.
Here is original image — columns from the ruins of the Temple of the Vesta.
I opened the original Canon RAW image in Photoshop and made two copies, and saved all the TIFF files. Then for copy A, I went into Levels and changed the mid-point to 3 and saved. For copy B, I went into Levels and changed the mid-point to .25 and saved. This gave three images that were roughly +2 stops over, the original, and ‑2 stops under exposed.
Because HDR is depending on having multiple images to combine to create a larger dynamic range, this effect of faking the exposure differences is close (but of course not perfect) to what could have been captured in three separate shots.
The next step is to open all three of the images and go to the Automate->HDR option in Photoshop. Because there isn’t any differentiating EXIF data for Photoshop to draw on, one must tell the tool the exposure differences. For the newly “overexposed” I entered a 2 in the EV field, for the “underexposed” image I put in ‑2 and for the original image I put in 0.
After churning away and a little color tweaking, this was the result. As an side, one pattern that I do notice regularly with HDR is that clouds and skies will turn very blue in parts, and reducing the blue saturation alleviates that greatly.
My eventual goal with this was a black and white image, so I went into Lightroom and treated this new image as any other I was converting to b/w and now we have the final result.
I did have to take a good bit of time to edit this. Using the Curves tool, I was able to draw out more of the mid-range darks so the sky and foliage wasn’t so high-key. Evening out the intensity took a little time and use of the Graduated Filter tool.
Not as solid a result as if I had done three exposures on the scene, but still quite a bit more range in the presentation than in the original! Hopefully this final image also avoids the pitfalls of HDR photography: an over-processed effect, ghosting and unrealistic imagery. I am satisfied with this image, especially when reflecting on how it started.