[Insight-users] Urgent question about Examples/Filtering/FFTImageFilterFourierDomainFiltering.cxx.

[Luis Ibanez]

Hi Jim,

Thanks for letting us know that the use of the RescaleIntensityFilter
solved the problem that you were facing.


    Regards,


       Luis


------------------
Jim Stott wrote:
> Hi Luis,
>  
> After adding a RescaleIntensityImageFilter to the pipeline, my problem 
> was solved.
>  
> Thank you for the help! I definitely need to practice more with this 
> great toolkit.
>  
> Jim
> 
> On Sun, Apr 6, 2008 at 8:28 AM, Luis Ibanez <luis.ibanez at kitware.com 
> <mailto:luis.ibanez at kitware.com>> wrote:
> 
> 
> 
>     Hi Jim,
> 
> 
>     1) BMP does not support pixel type float or double.
>       This is not an ITK limitation, is a limitation
>       of the BMP file format:
>       http://en.wikipedia.org/wiki/BMP_file_format
> 
> 
>     2) PNG does not support pixel type float or double.
>       This is not an ITK limitation, is a limitation
>       of the BMP file format:
>       http://en.wikipedia.org/wiki/PNG_file_format
> 
> 
>     3) You don't need to resort to VTK in order to
>       save images of pixel type float or double.
>       You can do so with the fileformats listed
>       in my previous email, and for which there
>       is currently support in ITK.
> 
>     4) Depending on what you want to do with the
>       output of the FFT filter, you can simply
>       cast-and-rescale the pixels of the output
>       image, by using the RescaleIntensityImageFilter.
> 
>       You can follow the examples:
> 
> 
>        Insight/Examples/Filtering/
>            FFTDirectInverse.cxx
>            FFTDirectInverse2.cxx
>            FFTImageFilter.cxx
>            FFTImageFilterFourierDomainFiltering.cxx
> 
> 
>        E.g. lines 259-268 of FFTImageFilter.cxx.
> 
> 
>        The output image will "look like" the real
>        or imaginary part of FFT computed from the
>        input image. The values however will be
>        rescaled.
> 
> 
> 
>        This will prevent you from doing things like
>        verifying the transformation by running an
>        inverse transform.
> 
> 
> 
> 
> 
>      Regards,
> 
> 
>          Luis
> 
> 
>     -----------------
>     Jim Stott wrote:
> 
>         Hi Luis,
>          Thanks for the prompt answer!
>          I noticed that VnlFFT only deals with float or double data. I
>         am wondering, within the domain of ITK, without resorting to
>         VTK, whether I can write the output from VnlFFT filter to BMP or
>         PNG files. Is that possible that I can cast the float or doulbe
>         output from VnlFFT filter to unsigned char before writing.
>          My objective is simple, just input a bmp file and save the
>         filtered image to another bmp file.
>          Thanks and have a nice Sunday!
>          Jim
>            
> 
>          On Sat, Apr 5, 2008 at 11:27 PM, Luis Ibanez
>         <luis.ibanez at kitware.com <mailto:luis.ibanez at kitware.com>
>         <mailto:luis.ibanez at kitware.com
>         <mailto:luis.ibanez at kitware.com>>> wrote:
> 
> 
>            Hi Jim,
> 
>            In order to save images with pixel type float or double
>            you should consider using:
> 
> 
>                a) MetaImage   .mhd
>                b) VTK         .vtk
>                c) Nrrd        .nrrd
>                d) Nifti       .hdr
> 
> 
>            Please see the FAQ in the Wiki for a list of the
>            file formats supported in ITK:
> 
>               http://www.itk.org/Wiki/Itk_FAQ
> 
> 
> 
> 
>            Regards,
> 
> 
>               Luis
> 
> 
> 
>            ------------------
>            Jim Stott wrote:
> 
>                Dear all,
>                 I am a new user and in a hurry to use ITK for a project.
>                 After I compiled FFTImageFilterFourierDomainFiltering.cxx, I
>                tried to run it. I intend to save the result image to a
>         BMP or
>                PNG file. The error message suggests that "BMPImageIO
>         supports
>                unsigned char only". I read the ITK user mannual about this
>                example (page 256, 6.10.2), it doesn't mention anything about
>                what image format you can save to.
>                 Is that because the output of VnlFFT filter cannot be
>         processed
>                by ImageFileWriter? If this is the case, how can I change
>         code
>                in order to save the result image to a BMP or other image
>         formats.
>                 Many thank!
>                 The following is the error message
>                        filter.exe  input.bmp  mask.bmp  result.bmp (
>         This is my command
>                line input.)
> 
>                        Error writing the real image:
> 
>                        itk::ExceptionObject (0131EC58)
> 
>                Location: "void __thiscall itk::BMPImageIO::Write(const
>         void *)"
> 
>                File: ..\..\..\InsightToolkit-3.4.0\Code\IO\itkBMPImageIO.cxx
> 
>                Line: 650
> 
>                Description: itk::ERROR: BMPImageIO(01823740): BMPImageIO
>                supports unsigned char only
> 
> 
>              
>          ------------------------------------------------------------------------
> 
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