FEATHER Algorithm

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FEATHER Algorithm

          FEATHER use the following steps
        - Make oversampled Fourier Transform of both HIGHres and LOWres images
        - Compute the truncation function f(r)
        - Make the Truncated compact Fourier Transform, f(r) x T(LOW)
        - Make the complement long baseline Fourier Transform, (1-f(r)) x T(HIGH)
        - Sum them T(ALL) = R x f(r) x T(LOW) + (1-f(r)) x T(HIGH)
             where is taken from FEATHER_RATIO
        - Make the inverse Fourier Transform
        - Truncate the resulting image to original size and Mask of the HIGHres
          images

        If LOWres is a single-dish image, f(r) should normally be  the  beam  of
        that  telescope to use optimal Signal-to-noise ratio from that data set.
        However, because of pointing errors and other calibration issues such as
        spectral  baseline, using a sharper transition function gives better re-
        sults. FEATHER uses a  exp(-(r/Radius)^Expo) function, where  Radius  is
        taken from FEATHER_RADIUS and Expo from FEATHER_EXPO.