HDR on the Charles River

School’s out for winter break, but that doesn’t mean I don’t have anything to share with you! I’ll have photos to accompany our adventures in Michigan this week, but that is still to come …

Our last two weeks of class before break focused on Photoshop and integrating it into our studio work. It was really nice to see the professionally applicable uses of Photoshop instead of just messing around with it for fun, which is what it felt like we had been doing with it up until these modules.

I’ll show you some of my studio work later this week, but I wanted first to share a very interesting exercise we completed in Photoshop III: High Dynamic Range, or HDR, photography.

You may have heard about HDR already, and some say it’s had its day and is now passé and overdone, but I think it’s still pretty awesome.

The principle behind HDR is that the camera can only capture a certain dynamic range of light, the differences between the darkest dark shadow and the brightest bright highlights, in one shot. The human eye can distinguish many, many more gradients of light than the camera can. HDR software tries to make a photograph’s range of light come closer to the human eye’s, and because we rarely see that in photographs, it looks CRAZY.

Here is my completed HDR image, taken from the MIT/Cambridge side of the Charles River looking over onto a nondescript section of the Boston side:

The process of creating a HDR image is a bit more complex than simply hitting the shutter, but still quite simple, once you understand what HDR software does and needs to do its thing.

What you do is take the same exact photograph (so get out your tripod!) at several different exposures. You expose optimally for the shadows so that they are not so dark, and optimally for the highlights so that they are not so bright, and do several exposures in between, too. HDR software (and Photoshop, which has HDR capabilities, as well) combines the different exposures and magically knows which parts of each shot to keep so that every element in your final photograph is perfectly rendered in full detail.

Voilà! HDR. A very cool technique, though not one I’m going to be using everyday. It’s been pretty great to get exposed to these processes that were mysteries to me just a few short months ago. Another point for photo school!



Filed under Boston, HDR, Landscape, Photo Assignment, Photoshop, School

6 responses to “HDR on the Charles River

  1. Mom

    The variances in the black/white/grey are stunning.

  2. Nice job!

    Figured I’d chime in since I know a bit about this from my math stuff in the last few years… turns out the “decision” that an HDR program makes to choose where to select high lights and where to select darks is highly algorithmic… and there are different algorithms for different types of scenes (e.g. one algorithm may be better for natural countryside landscapes, some may be better for urban scenes, while others are better for human faces). Adobe photoshop does a decent job guessing, but you might like to look into some of the open source options as they let you manually select the algorithm.

    If you really want to get techy you can do HDR+image stacking to simultaneously remove noise so you can crank the contrast. I’ve yet to successfully do one of these, but I’ve done a few HDRs and a few astrophoto image stacks, so putting the two together is the next project…

    Oh, and one last thing: I think some sort of jquery/javascript zoom on your photos to enlarge them would be nice when we go to click on them to get a closer look.

    • Thanks, Greg – great insight! We did use Photomatix for our HDRs, though our instructor said that CS5’s Photoshop has improved to the point where it’s fine to use in place of other software. I haven’t tried it yet in CS5, though, so we’ll see …

      Good to hear from you!

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