This presentation describes STAS (space-time analysis stream), a suite of advanced signal processing codes for the detection of dim targets in 'look-down' IR clutter. STAS has been tested on several hundred thousand IR clutter scenes in the NAWC SkyBall Data Base, and has been shown to be very robust. Code modules in the STAS detection stream perform the following functions: (1) calibration, bad-pixel identification and editing; (2) image registration, clutter estimation and clutter subtraction; (3) velocity stacking and matched-filtering. Other code modules in STAS allow synthesis and rework of IR images, to emulate data from arbitrary IR sensors, with arbitrary trajectories over the clutter scene. THe theory and performance of various STAS modules will be described, with emphasis on registration method, fast methods for mapping from the focal plane to the ground, treatment of bad pixels, digital interpolator design/implementation, and matched filter design. Examples of processed IR images will be displayed.