HDR: When Even Magic Has Its Limits

Used properly, High-Dyanmic Range (HDR) imaging can almost do magic. Scenes with huge contrast and uneven lighting can be turned into pristine almost studio quality images. Like many tools it can also be a great crutch. While I certainly don't take professional pride in using techniques that way sometimes it is the only option available. That's the situation I was in when visiting Niagra Falls recently. We arrived to a gray sky, mid-day, and traveling quickly. I didn't expect to get anything great, but I did want to capture some "snaps" of the falls, so here's what I did and how it worked out...First I realized that I'd have to use some type of HDR. The American Falls (the ones which were visible from the Park on the Canadian side where we were located) were not only backlit but the sun was in my frame and making a hash out of the clouds by turning the whole sky muddy. The range was dramatic enough that I cranked the bracketing on my D700 up to use 5 frames--giving me -2, -1, 0, +1, and +2 to work with.

Unfortunately I didn't have a tripod so I knew I'd need to use a fast shutter speed, fire a burst and hope for the best. Since I'd be using HDRSoft's PhotomatixPro later on I could rely on its intelligent image combination to do a fairly good job of lining up the images. Fortunately there was plenty of light so even at an ISO of 400 I could get a shutter speed of 1/1000s @ f/8. I wished I'd had a vertical grip on the camera or was using my faster Nikon D300s, as the Nikon D700's lower frame rate would make the later merge more difficult.

Since I wanted to ensure that the image looked as natural as possible (no easy feat once we've tinkered with nature enough to render a truly backlit image onto a low dynamic range computer screen or piece of photo paper!) I used the Tone Compression settings in PhotoMatix Pro. Tone Compression does a great job of trying to map the wide dynamic range of the set of input images into the compressed range available for output without making the image look too "grungy" or having too much of that obvious "HDR" look. Unfortunately it often crushes the highlights in the process. In this case since I really wanted the water to sparkle I used the White Point slider to set the white point to make the spray from the falls a pure white. That put the "snap" back in the image that compressing the range threatened to take away.

Niagra Falls American Side Falls HDR ImageNiagra Falls American Side Falls HDR Image

After that I could simply open the image in Photoshop CS5 and run my standard raw batch action of Noise Ninja & nik SharpenerPro Raw Sharpener and print.

To give you a sense of how the scene started out I've placed a copy of the single image (non-HDR) version below the HDR version.

So what didn't work? Two things. First, the color just isn't as good as it would have been if I could have come back for an early and warm sunlit morning. I could tweak it a little more but there isn't any way to fully recreate natural, warm sunlight.

Second, the images are not perfectly aligned. If you look closely at the observation tower on the left you can see that it isn't sharp in the final image even though it is in each of the single frames. Not enough to ruin it for a snapshot or a family slideshow but certainly the final image isn't really suitable for professional use or publication.

But since the last time I had a chance to visit Niagra Falls was as a child with a $30 Kodak Instamatic the image is certainly a big step up from my previous ones!


Niagra Falls American Side Falls Original Poorly Lit ImageNiagra Falls American Side Falls Original Poorly Lit Image

Joined: 2004-04-01
HDR: When Even Magic Has Its Limits

Great idea David, I'll have to try it out on some of my lackluster shots.


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