I am fascinated by a processing technique called HDR (High Dynamic Range) and have been eager to give it a shot (pun intended) for some time now. Read about HDR on Wikipedia – basically you take at least three shots of the same scene at different exposures. You then use HDR software to combine the images and the result is a photograph with a lot more depth and a higher range of colours. This is a new technique so there aren’t any rules about good HDR processing; this is the most significant pro and con of the technique. To view an HDR image on a regular screen you need to add tone-mapping effects and convert the image back to an LDR image. This process is often grossly exaggerated and can result in very surreal looking images. If my explanation didn’t make any sense, you’ll find plenty of literature online, just search for HDR.

I recently decided to love London (despite her acting like she hates me), so I figured spending some time taking photos of her would be a good place to start. I set off to Tower Bridge with my very handy GorillaPod and my camera set to auto-bracketing.

It was a lovely sunny day when I left home but the clouds rolled in as I approached my destination. The grey weather made my photos a bit dull, but HDR processing really gave them a whole new life.

I wasn’t overly ambitious with the original images. I started shooting on P (before realising that the depth of field was changing), then I switched to Av. I only shot in JPEG, but will use RAW for future attempts. I will also be more daring with my settings on forthcoming HDR experiments.

There are a number of ways to process HDR images, Photomatix and Photoshop are the most popular and most expensive programs. I opted for free software called Qtpsgui. It has so many options and really can be quite confusing.

I fiddled around with different plugins trying to understand what all the sliders mean. I liked the results from Fattal, but for some reason it is completely dependent on the output file size (so all my small tests looked great, but the final large image was terrible). Mantiuk gave me the best results on default settings and tweaking the parameters made a significant difference.

I eventually settled on three Mantiuk settings for results I liked best for this set of images.
I kept Pregamma set to 0.394 and Saturation factor at 1.6

Then simply changing the contrast settings gave three different results.

Contrast Mapping = 0.1 (a fairly realistic image)
Contrast Equalization = 0.1 (a very surreal, often too fake looking image)
Contrast Equalization = 1.0 (surreal, but pushing up the contrast made it less extreme)

So here are all my HDR images. I’ve posted the original photo (the ‘correctly exposed’ one) as well as a few adjustments. I’m still learning so I’d apprecaite any feedback on these.