pro psf_fft,image,psf,fftp ;+ ; fft_psf ; ; compute fft of a point spread function inserted into an image ; with the same size as an input image ; ; INPUTS: ; image - image with size of the desired psf fft. ; psf - point spread function ; ; OUTPUTS: ; fftp - fft of the psf ; HISTORY: ; version 1 D. Lindler ; 05-27-05 M. Desnoyer - Centered the psf based on flux ;- ;--------------------------------------------------------------------------- s = size(psf) & nsp = s(1) & nlp = s(2) s = size(image) & ns = s(1) & nl = s(2) ;; Get the center of the psf based on flux. Rick White's method xx = lindgen(nsp, nlp) yy = xx/nsp xx = xx MOD nsp ptot = total(psf) xcen = round(total(xx*psf)/ptot) ycen = round(total(yy*psf)/ptot) p = fltarr(ns,nl) p(0,0) = psf p = shift(p,-xcen,-ycen) fftp = fft(p,-1) return end