Shift-and-add

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The shift-and-add method (more recently "image-stacking" method) is a form of speckle imaging commonly used for obtaining high quality images from a number of short exposures with varying image shifts. It has been used in astronomy for several decades, and is the basis for the image-stabilisation feature on some cameras. The method involves calculation of the differential shifts of the images. The images are then shifted back to a common centre and added together. This provides an image with higher resolution (higher signal-to-noise at high spatial frequencies) than a conventional long exposure image. A number of software packages exist for performing this, including IRAF, RegiStax, Keiths Image Stacker, Stekkit and Iris.

[edit] References

• Baba, N.; Isobe, S.; Norimoto, Y.; Noguchi, M. Stellar speckle image reconstruction by the shift-and-add method, Applied Optics (ISSN 0003-6935), vol. 24, May 15, 1985, p. 1403-1405.