Government and private surveillance companies have a new weapon. Software developed at SRI International in Menlo Park, CA, can identify words and numbers in moving video taken under difficult conditions. The software locates characters, extracts them from the background, and adjusts for lighting or angled views. Gregory Myers, program director at SRI, says the software could be used in applications ranging from video archiving to homeland security.

The software works by examining each frame of a video for sharp lines set against a contrasting background -- telltale indicators of character strokes. Since text often persists over many frames, the software also looks for text similarity among frames to increase accuracy. If characters are warped or unclear, image-processing algorithms straighten them and even out their tone. The cleaned-up characters are then fed into optical character-recognition engines that convert them to machine-searchable text.