Spatial frequency restoration [radar imagery of ocean waves]

Spectral estimation methods, other than those based on the simple Fourier transform (FT), are generally computationally expensive in both resource usage and operation count-though they are potentially more accurate than Fourier methods. With regard to the burgeoning amounts of real imagery of ocean waves etc., it is useful to see if it is possible to wring more information out of the Fourier methods without overduly increasing the expense of the basic algorithm. A modification of a method, originally due to Wu and Thomas (1981) has been implemented as part of the CEC MAST-III MORSE project´s wave-analysis program, WASP, which seeks to estimate accurate wave parameters from small image samples. The new method acts to counteract the leakage problem since it is based on the complete theoretical knowledge of the response of the Fourier coefficients that result from the FT of a pure single sinusoid in a truncated and sampled image. The method is described and briefly compared with another method included in WASP, the auto-regressive method due to Cariou (1991)