Improved multilook techniques applied to SAR and SCANSAR imagery

The multilook processing used in SAR (synthetic aperture radar) image formation to reduce the speckle noise is considered. Two multilook techniques are proposed for improving the radiometric resolution without altering the geometric resolution and the characteristics of the impulse response. These techniques are based on the formation of looks with different bandwidths. The final image is formed by giving each look a proper size and weighting, and by adding them incoherently. The looks with wide bandwidth contribute to an improvement of the overall geometric resolution, while the looks with narrow bandwidth improve the overall radiometric resolution. The equivalent number of looks is more than 2.3 times the number of independent looks and is superior to conventional multilook processing with overlapping. Finally, using the proposed techniques, an algorithm for efficient SAR and ScanSAR processing is presented, and its validity is proved by image comparison and analysis.>