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The Modulation Transfer Function (MTF) for a full-disk solar intensity image can be estimated using the zero crossing properties of the Fourier Transform of the image (Toner & Jefferies 1993). We show that the MTF can be used to restore an image for the adverse effects of the earth's atmosphere and the measurement instrument's optics. The restoration process can be approximated for the special case of helioseismic analysis by using the estimated MTFs, after calibration onto a spherical harmonic degree l scale, to correct the time series of spherical harmonic transform coefficients.