Underwater Acoustic Imaging is the use of high frequency sound to derive images of objects underwater, usually on the ocean floor. Used to augment optical imaging techniques when optical visibility is too short, acoustic imaging must still provide timely (i.e. real time) information with respect to the actions it can affect. At present, much of the signal processing for underwater acoustic imaging is performed electronically in either analog or analog and digital forms. It involves primarily Fourier transforms and smoothing algorithms at present. Further signal processing in this area should be faster, and should encompass more operations, including image enhancement and 3-dimensional display processing. It is also possible that analysis of the time structure of the acoustic echo can provide information on texture, composition or other qualities of the object for display as color, although this area is still being researched. In short, underwater acoustic imaging is a promising field in need of significant amounts of real time signal processing to make it practical.