Capturing a moving HDR image

Capturing a moving HDR image

We’ve all seen HDR images doing the rounds in Instagram, Flickr etc. and heck, even your mobile phone probably has a setting on it now to capture a HDR image itself from the touch of a button. It can produce vibrant, interesting images full of impact. Usually the best results come from using your SLR camera attached to a tripod, but what if you want to capture something moving? I’ve got a little trick that I find works pretty well.

But what is HDR?

In case you don’t know, HDR stands for High Dynamic Range. It means that the end product of your shot has a higher range of highlights and shadows giving greater depth to an image, and more akin to what the human eye sees, as opposed to a camera sensor. For example, focus your camera on the sky, or a bright light such as a car headlight, and it will adjust to cope with that exposure setting, leading to the surrounding landscape, or car bodywork becoming much darker and losing detail. Likewise, focus away from that and the sky or headlight will be “blown out” and too bright to retain much detail. HDR is a solution to this by using your camera to take at least 3 different exposures and combining them. The more traditional method is to use what’s called a Graduated filter on your lens, particular for landscape shots featuring the sky – this allows you to have 2 ranges of exposure, effectively darkening the sky so both will expose and produce the desired effect. However HDR on a PC can produce much more vibrant possibilities – as long as you don’t get over excited with the various sliders and options.

The Normal HDR Process

Normally I’d set the camera up on a tripod, and set the exposure bracketing of the camera to take at least 3 shots. What happens here is the camera snaps the first one at your “normal” exposure, that being when it’s in the ideal point with regards to aperture and shutter speed. It then takes 2 more shots at the limit you imposed in the camera settings, at for example +/- 2 stops. This means that the exposure in both directions is over/under exposed. What this gives you is access to the darker areas of the image, and likewise bright areas which would otherwise be overexposed. You end up with something like this:

On the left a standard shot with normal exposure settings – on the right the HDR equivalent from 3 exposures

Note how on the image the people moving around are blurred – this is because during the three shots they obviously moved. So unless you shout at everyone to freeze or jump in front of your favourite racing driver to get them to stop on track, surely HDR has no place in taking a photo of something moving? Not unless we cheat a little bit!

Keep it RAW

First off, I hope you’re capturing your shots in RAW, if not read up on them as they’re required for this next step. Setup your shot, get your exposure and shutter speed just right and capture it. Now when you get back to your PC, open up the RAW file in your preferred processing software. I use Canon’s standard Digital Photo Professional tool, simply because I am so used to it. Lightroom probably has a better workflow, whatever works for you.

Next, refine the image as normal, perhaps try to avoid adjusting the exposure right now. Then export that as your “normal” image. Now we’re going to mimic what the camera would do for exposure bracketing, and adjust the exposure either +1 or 2 in either direction, and export an image each time. We now have our 3 exposures. It’s worth quickly noting you can of course do many more exposures, you could end up with a smoother range. I’ve done 5 or 6 in the past for a particular shot, but most of the time 3 will suffice. What we’ve done here is “faked” exposure bracketing. If you want to really spend a lot of time, you could do many half stop exposures in both directions – but you may drive yourself mad!

Drop these into your preferred HDR processing software, Photoshop perhaps, but I use Dynamic Photo HDR. Again whatever you prefer. Follow the steps outlined in the help files of the software and process the shot as normal – you’ll find that with this method, it’s not quite as effective as the correct exposure bracketing. Sometimes I find the exposure rating is removed from the exported files, leading the software to get confused (you can add it back in using an EXIF data tool if need be). Also don’t overdo the effects on the image. I find with HDR, less is most definitely more. When HDR first came on the scene, the images looked outlandish, over saturated and “plastic” like in their appearance. All we’re aiming for here is to gently bring those shadows and highlights into play, grabbing more detail in the process.

Again, standard exposure of the moving image on the left, and on the right the same photo exposed 3 times

So there you have it, a moving HDR shot! Note how I’ve pulled out more detail from the darkened areas of the wheels, and the smoke above the stack has a more levels of colour in it. We also get more shine on the boiler. Why not mix it up a bit and try a black and white HDR shot too? You’ll be pleasantly surprised as it gives a very accurate traditional effect to black and white. Be warned, this won’t work for every shot – if you find it’s simply not working for you, it may be that your original shot is just right. The same could probably be accomplished using a single image and a lot of patient levels/curves adjustment and layer masking but you’d be working with a flat image, so your options would be limited.

Don’t think of this as a be all and end all solution, but just another option in the toolbox.

Black and white HDR images can have quite an impact

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.