SUPERRESOLUTION TECHNIQUE WITH EDGE-BASED RINGING REDUCTION FOR PASSIVE MILLIMETER-WAVE IMAGES

Images obtained by passive millimetre-wave systems are heavily blurred and band-limited owing to diffraction. A superresolution algorithm has been developed to improve their spatial resolution beyond the diffraction limit. Initially the spectrum of an image is restored within the passband but the resulting image then contains strong ringing owing to the lack of higher spatial frequencies. These ringing artifacts are then reduced using a piecewise-linear model which identifies and restores sharp edges, so introducing higher spatial frequencies beyond the passband. This method has been applied to synthetised and real millimetre-wave images, but may have applications in other fields such as in magnetic-resonance imaging.