From: Wheeler, F. W (Research) <wh...@cr...> - 2003-08-04 18:04:28
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vnl_fft_2d::bwd_transform uses unusual scaling. Your problem may be that you need to multiply by N*M (rows*cols) after using it. Make sure you also test on something bigger than a 2 by 2. Note that the FFT code in (vil_algo/vil_fft.h and vil_fft.txx) vil_fft_2d_bwd() scales so that the inverse truly reverses vil_fft_2d_fwd(), but that code works on a vil_image_view object, not a vnl_matrix object. Fred Wheeler > -----Original Message----- > From: Manuel J Marin [mailto:mjm...@ya...] > Sent: Monday, August 04, 2003 1:48 PM > To: vxl...@li... > Subject: [Vxl-users] VNL FFT2 inverse doesn't work > > > I'm trying to get the inverse FFT2D with vnl_fft_2d. > But it always returns forward FFT. > > I've tried with : > > vnl_fft_2d<float> fft_ (2,2); > > fft_.transform(mcm, -1); > ... > fft_.bwd_transform(mcm); > > What's wrong? > > Thanks. > > Manuel Jesus Marin > SPAIN > > > > > ------------------------------------------------------- > This SF.Net email sponsored by: Free pre-built ASP.NET sites including > Data Reports, E-commerce, Portals, and Forums are available now. > Download today and enter to win an XBOX or Visual Studio .NET. > http://aspnet.click-url.com/go/psa00100003ave/direct;at.aspnet _072303_01/01 _______________________________________________ Vxl-users mailing list Vxl...@li... https://lists.sourceforge.net/lists/listinfo/vxl-users |