July 6, 2005

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  Rocky Mountains, sunset, looking north west from just above the tree line, Mt. Evans summit road, Colorado.

  Click for a bigger version. The source image is much, much bigger. Not as big as the mountains, however.

  Update: Ok, sandiegogal asks very politely about this photo, so I'll give the technical explanation.

  But first... The obligatory 1:1 crop.

  

  There are 8 source images, all shot with the camera mounted on a tripod. I'd like to get a spherical panoramic head, but none really satisfy the price/quality ratio at the current time. I shot the sources in portrait orientation, using a conventional pano head. I used a 135mm lens, f/16, and something like 3 second exposure. Viz:

  

  Each image is shot as a RAW file and converted to a 16-bit TIFF file, so there's no lossy compression. This happens in Photoshop.

  Then I fired up hugin and began the stitch. hugin is a frontend for software called PanoTools, which works by aligning images based on control points they have in common. Much of the process within hugin involves setting control points, which was difficult with these images. They have a lot of indistinct overlap area. It took some serious tweaking.

  Next came the waiting. I told hugin to use software called enblend to disguise the seams between the pictures. The image warping part took a half hour, but enblend took all afternoon. I left and did some shopping and came back and it was still working.

  The end result was well blended and stood up to scrutiny. Loaded into Photoshop, I made an effects layer for Levels and brightened the gamma a little bit. Then I painted a gradient mask on that effect layer so it only applied to the bottom third of the image. Cropped off the inevitable ragged edges that come with doing a stitched pano, and saved as a PS document, 303 megabytes.

  I hope to print it out at it's full potential size at 250dpi. That'll work out somewhere around 40" x 10". I could go back and interpolate the RAW files into higher resolution images and re-do the process, to end up with something that I could print about 25% larger, but I'll wait to see how well this outputs at different resolutions before I do.

  I won't give away a jpeg for a few reasons, all having to do with quality control. I can't feel good about sending someone a jpeg of this image, even at full resolution, because it'll be 8-bit and have compression. No printout you make would be as good as it should be. The PS file (or a correpsonding 16-bit TIFF file) fills half a CD, and would only really be useable in specialized software.

  I'd like to work out a way to let people order their own fine art printing of this photo (and others) from some online source, but I have to do the research.

  Anyway. There you go. More than you wanted to know about it.

  • 4:46 am
  • 11 Comments