HDR Photography
Category: Photography...
Posted Tuesday, August 29, 2006 at 03:15 PM [GMT-6]

I've been educating myself on high dynamic range imaging (HDRI), which is a fancy name for averaging under- and overexposed images to come up with one that provides a full range of detail, from dark shadows to the brightest highlights. The Wikipedia entry for HDRI explains the theory behind the process, albeit not in an especially edifying way.

I've downloaded a program designed specifically to create HDR images from digitized photos, and it provides fairly impressive results. The application is Photomatix Pro, by MultimediaPhoto. While it provides a good deal of flexibility in manual processing, it also has an auto mode that essentially allows you to combine the dynamic ranges of two images into a third image with one click of the mouse. Below is a real life example of my first attempt at using the software.

The first three photos were taken using Auto Exposure Bracketing, which instructs the camera to take three photos: one using the "normal" exposure, and two more using exposure settings which are under and over the normal setting. The first photo is the "normal"; the next two show the underexposed and overexposed duplicates.

Photo - Normal Exposure
Photo - Under Exposure
Photo - Over Exposure

The next image is the "averaged" or HDR image, using the under- and overexposed images. Note how the tree outside the window is visible as is the detail of the indoor bookshelves.

Photo - HDR

OK, granted these are not the best examples of HDRI, because the original photos are low quality (I did no tweaking in Photoshop). However, this type of image is a good example of a problem setting for most photographers: a relatively dark setting with a big bright spot right in the middle. In any event, perhaps you get the general idea. If you want to see some really impressive examples of HDR processing, visit the HDR pool at Flickr. Some amazing images have been created using HDRI techniques. You'll see that HDRI can be used for effects other than simply recovering detail lost in shadows or blown-out hightlights.

Note that if you have Photoshop CS2, it provides a tool for HDRI creation. I don't have CS2 so I can't compare it to Photomatix. But, in the short time I've used the latter program, I can tell it's going to be a useful tool for specific situations.

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Comments

I don't know much about these things so this was new and interesting. I actually like the underdeveloped photo (lol) and the one you used HDRI on - the trees give it a back focus (that's my own made up technical sounding term).

Posted by: Catez at August 29, 2006 07:29 PM

I actually like the underdeveloped photo

I completely agree that "artistic" photos can contain elements that would be considered flaws in other contexts. However, clients often want ultra-realism (my own technical sounding term ;-), not artsy effects. That's where HDR comes in handy.

But, it's all new to me, too...I'm just now learning about it.

Posted by: Eric at August 29, 2006 08:28 PM

That's some good stuff, Eric. It's not often that I want to keep detail in the dark areas, since I'm usually using it to frame what's in the light area, like this or this. But there have been times when I've wished for the ability to strike the compromise you've illustrated here.

The program you downloaded... shareware?

Posted by: Foo at August 30, 2006 07:38 AM

Foo, it's commercial software -- $99 -- but you can download a fully functional demo (it watermarks the HDR image).

Nice pics, by the way!

Posted by: Eric at August 30, 2006 07:49 AM

Hey, that's really informative. I think I may read up a bit and see if it is possible to do it manually on Photoshop 7.0.1. Thanks. :)

Posted by: mis_nomer at August 30, 2006 11:38 AM
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