A High Dynamic Range (HDR) image from a single exposure
The most common way to create a HDR image is with multiple shots of the same scene, all at different exposures. I think most people would argue that this is the only way to create a true HDR image, however it is still possible to get interesting results from a single exposure – in fact sometimes it can be a less problematic way to work.
A common problem with multiple exposures is excessive movement – Photomatix can correct a certain amount of movement, but it can’t work miracles – if you’re taking a shot with trees in on a windy day there is a strong chance that you are going to end up with blurred foliage. Clouds can also cause problems, with them appearing to stutter across the sky in the finished image.
My source image
When taking this shot I used the histogram to make sure I got the brightest possible exposure I could without getting any blown highlights (the things that blink on the display when you look at the shot you have taken). As it was dusk when I took this shot the exposure is reasonable well balanced, if a little bright – it doesn’t have an incredibly wide dynamic range which makes it perfect for processing like this.
Creating the HDR
There were then two ways for me to process this single file in Photomatix
- Using the single raw image
- Creating images at different exposures – Using image processing software (Photoshop, Lightroom, GIMP etc) I created multiple versions of the same image, each with the exposure level adjusted – then processed these in Photomatix as if I’d taken multiple exposures at the time.
1. Using the single raw image
In Photomatix, choose “Open” from the file menu. Photomatix will then open the file and convert it to a pseudo-HDR. Photomatix will tell you that you really ought to use multiple exposures but it will let you process it in the usual manner. After some limited adjustments from the default settings, this was my result…
As you can see, it doesn’t look as flat as the original image, and the sky certainly looks more dramatic.
2. Creating images at different exposures
First I saved my original image as a TIF (IMG_8201.TIF), then darkened the image by 1 stop by changing the exposure to -1 in Lightroom – I then saved this image with a different filename (I added -1 to the name so that I knew which image it was, IMG_8201-1.TIF). I repeated this process until I had 5 images in total, with the last one having an exposure value of -4.
(Of course you could also increase the exposure of some of your images, however doing so may introduce noise into the finished image.)
Then I began to process the images as I would any other HDR – choosing “Generate HDR image” from the Workflow Shortcuts and then providing Photomatix with the location of the files when prompted.
The image below was created using the same settings as were used for the previous image.
As you can see there is quite a difference between the two images, even though the same settings were used – this is because I also provided the darker images, which have helped add texture to the stone and the clouds.
If I had to choose between the two images I’d say I prefer the second one as I’m more of a fan of dramatic HDRs but I have to concede that the results from using just a single image were much better than I expected.
A trial version of this is available at http://www.hdrsoft.com/download.html. Images produced with the trial version have a watermark added but it’s a good way to get to grips with the process before you part with your hard-earned cash. Should you decide to buy a copy of Photomatix, my discount code, “AndyStafford15″ will give you 15% off.
