static VImage create_fmask( int, int, int, double, double, double, double, double ); VImage disp_ps(); VImage flt_image_freq( int, double, double, double, double, double ); static VImage fractsurf( int, double ); VImage freqflt( VImage ); VImage fwfft(); VImage rotquad(); VImage invfft(); VImage invfftr();