HDR. A word likely to bring strong emotions into any debate about digital post processing. It seems to be one of those crazes that regularly do the rounds on the internet. Like tilt/shift lenses employed to make the subject appear to be a miniature model landscape, or bad colour casts deliberately added to make pictures look like they were taken with a 40 year old Soviet-era camera on outdated film and then subsequently developed in a mixture of coffee grounds and orange juice (past its sell-by date).
HDR is one of those techniques that can be extremely useful. It can help to circumvent the age-old problem of our photographic medium not being able to properly cope with the contrasts between very bright highlights and very dark shadows in a scene. As any technique, it can also be abused and over used, leading to garrish, super saturated, cartoon-ish pictures.
I should mention already now, that I am firmly in the “protect our eyeballs against HDR over-use” camp. I am quick to point out that it’s a technique that should be used sparringly, and I have also been known to use a few expletives to emphasize that point of view.
The basic idea is quite simple: When facing a scene with wider contrast than the camera can handle, take several differently exposed pictures, and let a computer pick the details in the shadows from an over-exposed images and the details in the highlights from an under-exposed image. Combine these with details in the midtones from a normally exposed picture, and the result is a “high dynamic range” image, or HDR. Sounds very useful, right? It is. The problem, or “artistic challenge”, if you want, is to avoid glowing edges and shadow areas that turn out to be brighter than the highlights.
I have been fascinated with the towers of Canary Wharf for years, and I regularly add a different view of them to my photo collection. Last night my friend Steve and I went to the Thames Barrier to see if we could get a good view with the tall towers of Canary Wharf with the alien-looking machine houses of the Barrier in the foreground. We could. And as an added bonus, we could even include the O2 in the same shots. Postcard photographer, eat your heart out!
When we had captured enough variations on the theme of “Canary Wharf seen through the openings in the Thames Barrier”, we went to the O2 which is just down the road. The building (super sized tent, really) started its life as Tony Blair’s miserably failed attempt at building a suitable memorial for himself called The Millenium Dome. After the tax payers had lost a small fortune, the government almost gave it away, and now it’s a successful music venue. But that aside, it is placed almost on top of the Blackwall Tunnel, just a stone throw from Canary Wharf. We managed to find a slip leading down to the Thames where we could park the car (shhhh!) and then set out to capture a few extra shots.
When taking night time shots, I prefer to take them in the blue hour right after sunset. There is a brief moment, where the electric lights in floodlights, apartment windows, street lights, etc, balance with the ambient light in the sky beautifully. Sadly, this great light lasts only 5 to 10 minutes, and I find it quite difficult to see whether it has passed. By the time we got to the O2, it had definitely passed. So yesteday I bracketed my shots. My camera (as indeed most DSLRs) makes it very easy to take a series of pictures with 1/3 or 2/3 stop difference in the exposure between them. This makes it a lot easier to get an image with good exposure when faced with a difficult situation, such as lit skyscrapers against a dark sky.
Today, as I was sorting through the takings from last night, I decided to give HDR a go. I had the raw material in my bracketed series as well as a couple of hours with nothing else to do.
My previous attempts at HDR (yes, I admit it, I have dabbled with the black art before) has been in Photoshop CS4 which has a so-so HDR function, as well as in Photomatix, a specialised HDR application that gets a lot of good feedback on the web. I never got my head around Photomatix, and I think it’s fair to say that CS4’s implementation was a bit of a stop-gap. So I quite looked forward to see if the new functionality in Photoshop CS5 was as good as the reviews I’ve read has claimed. By “good” I mean that if a luddidte, like me, can get a decent result out of it, then it must be good.
There’s really not much to say about this, my first, serious HDR attempt. Photoshop did what the reviewers had claimed it would do. Although I wouldn’t be able to explain what the different knobs, dials and sliders in the user interface actually do, a bit of trial and error quite quickly resulted in what I considered decent night-time images. After that, it was just a matter of adjusting the pictures like I usually would do for night-time shots, by boosting the colours and clarity.
I hope I have avoided the worst cartoon-ish side effects of the technique. And while the pictures here are definitely pushing the boundary of colour saturation, that’s a deliberate choice made in Photoshop propper the same way I would have done if I had started with a single, normal picture.
So how does it feel to have completed my first HDR pictures? Well, I suspect it’s a bit like the rare Catholic priest that goes to visit a brothel for the first time. I still think that over-use of HDR is a sin, and I still think there’s a lot of sinners around. But at the same time, I also have to admit that it’s kinda fun, and I may even sneak back in for a second helping!
A gallery with bigger versions of these pictures can be seen here.