Single Photo HDR

November 9, 2012 at 4:14 pm

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.