Monday, March 09, 2009

Exposure Fusion with Enfuse

Today was a good day. I got my favorite f/1.4 50mm telephoto lens back from the repair shop. What's more, the repair (impact damage--ouch!) only cost me $100 to fix. Thank goodness for that.

With the new lens at home, I took the opportunity to try a new post-processing technique I learned about on the Internet. It's called Exposure Fusion, and it is likened to a poor man's HDR tonemapping. Both techniques operate on the principle of combining multiple exposures of the same photo to pull detail out of areas that might be over or under exposed in any one photo. The result is a beautifully balanced, and sometimes surreal photo.

HDR is all the rage right now, but when I tried to do it, I couldn't get a photo that looked decent. HDR and tonemapping is very complicated, and I just couldn't get it to work for me. So when I saw the article for Exposure Fusion, I thought I would give it a try.

The tool is called Enfuse, but before I could try it, I had to download and compile the software for Ubuntu, which was fairly trivial, but took a couple of hours. The wiki also provides instructions for installing a nice looking panorama stitching toolset called Hugin, which I'm eager to try next.

So, for Exposure Fusion, here was my experiment. I took five photos of our clothes drying rack. (Yes, I know, mundane subject, but it serves to illustrate the concept.) Notice the windows, which are very bright, against the chair and table, which are darker, and in shadows.

All photos were taken with ISO 400, f/1.4 and exposure settings of AV -2, -1, 0, +1, and +2. I was too lazy to get my tripod, so I just set it on the table and held the camera really still.

After running the five photos through the tool, here is the resulting photo. Pretty impressive! I'll need to find a better subject and maybe I will post something later that's a little more illustrative and aesthetically pleasing.

A close inspection of the photos will reveal less noise in the composite photo, and a nice balance between bright areas (like the windows) and dark areas (like the chair). Plus, I think the composite is a bit more saturated than the originals.

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