High Dynamic Range Imaging

I’m starting to play around with HDR or High Dynamic Range images. Ordinary camera images, computer displays, and prints have a limited ratio between the brightest and darkest parts of an image.  This can result in having no detail in either highlights, shadows, or both.  While there are a few devises around that can capture a much wider dynamic range, HDR techniques usually stitch together a series of exposures to expand the levels of brightness in an image.  These HDR images are then mapped to standard range image in ways that allow us to see the greater detail at both ends of that range.  They do this by controlling contrast in local areas of an image, rather than across the whole image in the same way.  It takes advantage of the fact that we often look at images (be they photographs or the real world around us) one small piece at a time.  And we are masters of using local contrast, which is why we can see into shadows or bright areas in ways that cameras, including film cameras, are not capable of recording.

Here is an example of an regular image as captured by my digital camera:

Normal digital camera image

Stitching together three exposures, the one above, plus an overexposed and an underexposed image, and processing it through a HDR image program, one can get something like this:

An HDR image from 3 exposures processed with Photomatix.

HDR images can have a very photorealistic effect but with better views of dark and light areas of an image.  Sometimes the images can result in some deeply saturated colors as well.  But one can also get some strange and wonderful effects (or not so wonderful, in some cases) by playing with the settings when working with the image.  Here is an example of an image with a less smoothed application of the local contrast effects.

Another HDR image

I’m looking forward to seeing what I can do with these techniques to produce interesting or different images than normally available through standard digital photography techniques.