09 June 2011

Hugin - Free panorama photo stitcher

Point Lobos, California
Canon EOS 5D, Canon EF 100-400mm f/4.5-5.6L IS USM @100mm, 7 frames stitched.
A few years ago I'd concluded that panoramas and other "photo stitching" were simply not worth the trouble. My end results were hit-and-miss, with obvious mismatches from one frame to the next that needed hours of tweaking. This put me off photostitching of any kind for quite a number of years.

Then I discovered Hugin. It's a completely free bit of software developed as a front-end for Panotools, which is a very powerful program written by German physics and mathematics professor Helmut Dersch.

Hugin is not the most user-friendly bit of software. The shear wealth of features and options can be overwhelming, but that's because it is a truly powerful tool. Having said that, stitching together a panorama is actually pretty easy to do. Simply load up the source images, then do a bit of mouse-clicking to create some control points that help the software to match the images at the joins. The software will do everything else automatically, even correcting for exposure variations and lens distortion, and neatly cropping the end product.

The results are simply amazing. The above photo of Point Lobos, California, was constructed from seven individual frames that I shot handheld, yet the result straight out of Hugin is pixel- perfect at the joins, with no manual fixes needed whatsover. I expected to have to do some photoshopping where the seaweed was moving around in the water. Yet even here, Hugin managed to stitch the images seamlessly. Truly impressive!

So give Hugin a try. I for one will be shooting panaromas and other photo-stitches fearlessly from now. Just make sure you follow these tips to achieve the best results:

  • Use a tripod and spirit level when possible, especially for traditional panoramas. If your horizon isn't level Hugin will still manage to stitch the frames together, but you may lose a lot of the image in the final crop.
  • Keep the camera settings constant to ensure a consistent exposure and depth of field across all the frames.
  • Allow plenty of overlap from one frame to the next. The more overlap, the better the end result out of Hugin.
  • Avoid using wide angle lenses as they tend to suffer from distorted perspective that can be problematic to stitch.
  • Shoot RAW, and make sure any RAW processing is applied consistently to every frame prior to stitching.
  • Hugin can't handle RAW files directly, so convert to 16-bit Tiff's before importing to Hugin. Don't be tempted to work with Jpeg's as it will limit the processing you can apply to the end product. Save the stitched result as Tiff, too.
  • Use a wide-gamut color space such as AdobeRGB or ProPhotoRGB, rather than the standard sRGB. However, I found that Hugin did not assign the color space properly to the output image, so I had to apply it manually in Photoshop afterward.

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