[Insight-developers] two-input filters don't work

[Luis Ibanez]

Hi Michael,


1) What is the modality of the DICOM images that you are loading ?

2) I presume that you are doing this with 2D images.
    Is that correct ?

    If not, then you actully need to replace the ImageFileReader
    with an ImageSeriesReader.

It is unlikely that the problem is related to filters that
take two inputs.

We should verify first that the input images have the proper
pixel type.


    Regards,


        Luis


---------------------
Michael Xanadu wrote:
> Hi Kevin,
> 
> thank you for your reply.
> I looked at my feature image and initial level set image and found out, 
> that both images suit your requirements. Actually, all level set filters 
> work fine with image files, like it's described in the manual. But when 
> I use an itk::GDCMImageIO as input - forget about it...
> The clue is: Fast Marching Segmentation is the only one, which works 
> with dicom, the other three level set filters (Shape detection, Geodesic 
> active contours, Threshold Level Set) lead to the white spot I decribed 
> in the last mail. That led me to believe that the problem has something 
> to do with the "two-input" filters.
> Do you have any further information for me how to solve the problem? If 
> not, I think I have to learn the hard way, like you. :-(
> 
> Regards, Michael
> 
> 
> 2009/9/4 Kevin H. Hobbs <hobbsk at ohiou.edu <mailto:hobbsk at ohiou.edu>>
> 
>     On Thu, 2009-08-27 at 12:55 +0200, Michael Xanadu wrote:
>      > Hi folks,
>      >
>      > I've got a problem with all segmentation filters which have two
>     inputs
>      > (normal input & feature image), for example ShapeDetectionLevelSet or
>      > GeodesicActiveContour. I tryed the accordant examples in the example
>      > folders and they work great (with image files). But if I replace the
>      > input by a dicomreader (of course, I changed all accordant
>     parameters,
>      > too) I always get a black output with a little white spot at the
>      > coordinate where I placed the seedpoint. I messed around with the
>      > filter parameters, but I never get a segment, only the spot. Is
>      > somebody familiar with the problem?
>      >
>      > Michael
>      >
>      > P.S.: dicom data = 512 x 512 x 4, short
> 
> 
>     My guess is that your input images are not exactly right for these
>     filters.
> 
>     The examples given in ITK take great pains to set up the feature image
>     and the initial levelset "just so".
> 
>     The level set filters don't ever take a "normal input". I had to learn
>     this the hard way (very hard way in fact I just discovered that some of
>     my old work had edge images the wrong way around. It's no wonder they
>     seemed to stop early!) by disassembling the examples into many
>     reader->filter->writer programs and carefully looking at the outputs.
> 
>     The feature image should range from 0 to 1 with values close to one
>     inside and outside the object, and values close to zero at its edges.
> 
>     The initial level set image should have negative values inside the
>     object and positive values outside the object.
> 
> 
> 
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