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How to take HDR pictures

Last updated at 14:48, Sunday, 03 August 2008

Alan Cleaver explains the facts and the myths behind High Dynamic Range photography

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I am a big fan of HDR - high dynamic range photography - but I'm also aware there's a lot of confusion over what it is, when it should be used and how to do it. Confusion shared, not least, by me. But I thought I'd have a stab at an idiot's guide which people can feel free to correct.

The picture of me in my office illustrates one of the problems of 'normal' photography. Light shining in through the window at the camera would normally throw the subject into shadow. To get round this you would use fill-in flash or a reflector. But in this instance I used HDR - it takes the dark shadows and the bright window and blends them into something more akin to what the human eye sees.

How is it done? I took three exposures (normal, -2 and +2) and software from Photomatix merges the three into the result above. It is also possible to create an HDR image from a single RAW file but I find the results better from multiple jpegs.

Another example is the one shown of St Pancras station. Not surprisingly in the original shot all that light flooding through the roof threw everything into a mucky grey colour instead of the bright blue the human eye saw. HDR has returned the proper exposure for the statue and the blue ironwork while keeping the tourist in the centre of the picture also correctly exposed. This shot was created from a single RAW file and the result is not too bad.

But I know what you are thinking. These all look like 'normal' pictures whereas the HDR shots you see posted up on Flickr normally look like something created by Roger Dean. Well that's because people couldn't resist taking software designed to overcome the problem of heavy contrasts and use it for artistic effect. Push the buttons on the HDR software to the limit and you end up with something like the picture of the Ratty (above).

Now, you and I know that the Ratty steam train doesn't look anything like this - and yet the heavily HDR-d effect is not displeasing. HDR can be used to push colours and tones to their limits to create some very arty photographs but it's worth remembering that it's original purpose was simply to create more 'real' pictures.

How do I find out more? I'd suggest visiting Photomatix and downloading the free version of their software. The website includes manuals and you'll also find tutorials elsewhere on the web. But in short, take three different exposures (typically -2, 0 and +2) of a subject that doesn't move (and use a tripod) then use Photomatix to merge all three images and create the finished HDR image.

Here's a gallery of good HDR images, and in particular I'd look at Jakub Kubica's work.