Speckle suppression is the reduction of speckle noise in an image produced by a telescope. Speckle noise is a general term that includes signal noise inherent in the instrument.
Adaptive optics can be classified as speckle suppression, as do attempts to realize better angular resolution than indicated by the Rayleigh criterion. For the latter, the following practices are of use:
Combining information from such multiple images can be used to reveal detail otherwise hidden.
Speckle suppression has value for many types of observation, and is of particular interest when used in conjunction with coronagraphs for imaging objects very near stars such as extra-solar planets or protoplanetary disks. The term also applies to additional techniques for producing a good signal-to-noise ratio in direct imaging exoplanets. Nulling is using interferometry, specifically light interference patterns to place a dark band over the star. If multiple such images are taken, varying factors, processing can be devised produce an image taking advantage of the information each individual image captures.