[Insight-users] help! some problems : FFT : JPEG : RGB to HSV

[Luis Ibanez]

Hi  475126 !


1) Nope, there are not classes at this point
    for converting RGB images into HSV.
    However this can easily be implemented in
    one of the following ways:

    1.1) Create a new filter deriving from the
         UnaryFunctorImageFilter. You will only
         need to define the Functor that converts
         one RGB pixel into an  HSV one.

OR

    1.2) Create an ImageAdaptor. Please look at
         the Image Adaptors chapter in the software
         guide

         http://www.itk.org/ItkSoftwareGuide.pdf

         Again, in this case you only need to
         define a PixelAccessor that stablishes
         how to convert one RGB pixel into a HSV one.

OR

    1.3) Use the AdaptorImageFilter which takes
         the PixelAccessor that you would have written
         for option (1.2) and creates a Fitler with it.

-----


2) Yes, you can now read JPEG files in ITK.



-----


3) About the FFT,


    These two filters internally invoke VNL classes
    for computing the FFT in the specialized cases of
    1D, 2D and 3D.


    itkVnlFFTRealToComplexConjugateImageFilter invokes
    the fwd_transform() method that computes the *Direct*
    Fast Fourier transform.


    itkVnlFFTComplexConjugateToRealImageFilter invokes
    the bwd_transform() method that computes the *Inverse*
    Fast Fourier transform.


You will find the actuall definiton of these methods in

           Insight/Utilities/vxl/core/vnl/algo/

                   vnl_fft1d.txx
                   vnl_fft2d.txx
                   vnl_fft3d.txx




   Regards,


     Luis


--------------
475126 at unizar.es wrote:

> Hi all!
> 
> I have some problems:
> 
> Are there any classes to convert RGB images to HSV images?
> 
> Can I read .jpg images in itk? how?
> 
> Is used "VnlFFTRealToComplexConjugateImageFilter" to calculate fourier 
> transforms? 
> 
> And is "VnlFFTComplexConjugateToRealImageFilter" for calculating inverse 
> fourier transforms? 
> 
> Could someone help me?
> Thanks...
> 
> Excuse my english...
> 
> 
> 
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