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.

Long exposures in daylight

May 17, 2012 at 9:49 am

So occa­sion­ally (and hope­fully more often than that), I’ll drop in a lit­tle verbage amidst all the pho­tog­ra­phy here. Here is one of those times.

Ear­lier this week I read an arti­cle (1) that was related to doing long expo­sures in var­i­ous light­ing sce­nar­ios. Day­light, evening, etc. With the acqui­si­tion of a 5D Mark II, I’m look­ing for­ward to also try­ing new tech­niques than I had before. Not that they couldn’t have been done before, but I’m def­i­nitely want­ing to refresh the toolkit and new hard­ware helps with that.

With help from a local sup­ply shop (2) I got a new 3-stop ND fil­ter (3) for my Cokin P-series set, which com­bined with 2 other polar­iz­ers pro­vides 5 stops of extra expo­sure time. In other words, if you have a nor­mal expo­sure of 1/60 sec­ond then all else equal, with the above setup you would have an expo­sure of 1/2 sec­onds (1/60 * 2^5 = 1/2).

So yes­ter­day I grabbed a seri­ously fast sand­wich and went to the foun­tain down­town by Pack Square (4). It was very bright around 1pm so not great for super-long expo­sures. How­ever, the fol­low­ing did come out of the session.

Long Exposure May 16, 2012

13 sec­onds, f/32 at ISO 50. 100mm f/2.8 USM on 5D Mark 2

Granted, shoot­ing at f/32 is not rec­om­mended under nor­mal cir­cum­stances. But in the inter­est of a “long as pos­si­ble” photo I was try­ing to limit the light as much as pos­si­ble. Today is look­ing like another sunny day, but the next time it gets cloudy I look for­ward to see­ing what else can be done. Once I can get into the 2+ minute mark, then things like car move­ments can start to really blur.

Why do this dur­ing the day, when dur­ing the evening it is so much eas­ier? Two rea­sons, one because it’s there (5) and two, because I think that the energy of a space dur­ing the day with plenty of peo­ple and motion will give dif­fer­ent results than wait­ing until evening when the scene is calmer.

(1) http://www.bulbexposures.com/long-exposure-tutorial-old
(2) http://frenchbroadimaging.wordpress.com/
(3) http://www.bhphotovideo.com/c/product/155747-REG/Cokin_CP154_P154_Gray_Neutral_Density.html
(4) http://g.co/maps/bhmfx
(5) http://en.wikipedia.org/wiki/George_Mallory