Sticthing Panoramas

2007.06.22

There are several ways to create digital panoramic images but the widest and most detailed results are obtained by stitching several images together. It can be as few as 2 or more than a hundred. With hundreds of images, a panorama of over 1 gigapixel can be produced, that is over 1000 megapixels. Stitched panoramas can also span a very wide angle of view, even up to 360. These two properties often result in quite impressive photographs.

Digital panoramas can be stitched together using various specialized software or even generic imaging programs. There are a few digital cameras which are capable of producing limited panoramas within the camera itself. Neocamera reviewed the HP Photosmart R967 with that feature. If you look around you may be able to find o2 Mobile Phones which have panorama apps that work the same. Generally these cameras and phones limit the output resolution, the number of images and the stitching formation of panoramas stitched within the camera but it is quick and easy.

While the first stitching programs were tedious to use and produced poor results, enough to discourage most people from using them, the situation has considerably improved. Canon's PhotoStitch, for example, does a decent job with uncomplicated single-row panoramas as long as it likes the camera who took the pictures. Specifically, PhotoStitch refused to stitch image from the HP R967. It also does not support lenses wider than 20mm.

Technology has improved to the point where it is now possible to identify and generate a high-quality digital panorama without any user intervention - other than selecting images which include the images to be stitched. This amazing technology is demonstrated by the free AutoStitch program. While its technology is included in a few commercial programs, the functionally in AutoStitch is enough to produce great-looking panoramas.

AutoStitch is extremely simple to use. Simply by selecting a set of images, it creates a digital panorama from them. By default, the output resolution is low which results in a quick preview of the panorama. To produce a higher resolution panorama, simply visit the Edit->Options panel. There are several options there but only the Output Size group and the Other Options group are important. Each time options are changed, simply invoke the Stitch->Start menu item.

AutoStitch's performance is dependent on the number of images to stitch and the system memory available. That is why the memory options are important. If they are not set high enough, compared to the output resolution, AutoStitch runs gives an out-of-memory error. It does take advantage of virtual memory, so increasing the paging file size allows it to output larger panoramas. For a 16-image single-row parorama, each image having 10 megapixels and an overlap of roughly 25%, AutoStitch took about 1 hour on a 2 GHz machine with 1 GB of RAM and 2 GB paging file. So the process is quite slow but since no user-intervention is required, there is no need to watch the progress bars.

Below is a 3-image panorama merged by AutoStitch in about 10 minutes at full-resolution on the same machine as above. Canon's PhotoStitch could not merge the same images correctly because the focal length used was 18mm. The result is very good with no easily visible artifacts. Similar results were obtained for other several other panoramas. That is great motivation to capture more such digital panoramas...

• Digital Photography