# ITK - Concept checking error

**URL:** <https://discourse.itk.org/t/itk-concept-checking-error/1946>\
**Category:** Beginner Questions\
**Created:** [June 5, 2019, 11:44am UTC](https://discourse.itk.org/t/itk-concept-checking-error/1946 "2019-06-05T11:44:32Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Pooja\_Virkar](https://discourse.itk.org/user_avatar/discourse.itk.org/pooja_virkar/32/804_2.png) [@Pooja\_Virkar](https://discourse.itk.org/u/Pooja_Virkar)\
**Post date:** [June 5, 2019, 11:44am UTC](https://discourse.itk.org/t/itk-concept-checking-error/1946/1 "2019-06-05T11:44:32Z")

</div>

Hello,

I am trying to segment tumour in liver. I made one program which is working fine with 2D images.  
but when I am trying to run 3D series for the same program,  
its showing following “Concept checking” error.

/usr/local/include/ITK-4.13/itkConceptChecking.h:804:3: required from ‘struct itk::Concept::IsFloatingPoint’  
/usr/local/include/ITK-4.13/itkCannyEdgeDetectionImageFilter.h:220:3: required from ‘class itk::CannyEdgeDetectionImageFilter\<itk::Image\<short int, 3\>, itk::Image\<short int, 3\> \>’  
/home/PVirkar/Desktop/program/Tumour3Dwatershed/Tumour3Dwatershed.cxx:167:36: required from here  
/usr/local/include/ITK-4.13/itkConceptChecking.h:796:17: error: conversion from ‘itk::Concept::IsFloatingPoint::Constraints::FalseT {aka itk::Concept::Detail::UniqueType\_bool}’ to non-scalar type ‘itk::Concept::IsFloatingPoint::Constraints::IntegralT {aka itk::Concept::Detail::UniqueType\_bool}’ requested  
IntegralT a = FalseT();  
^  
/usr/local/include/ITK-4.13/itkConceptChecking.h:797:17: error: conversion from ‘itk::Concept::IsFloatingPoint::Constraints::FalseT {aka itk::Concept::Detail::UniqueType\_bool}’ to non-scalar type ‘itk::Concept::IsFloatingPoint::Constraints::ExactT {aka itk::Concept::Detail::UniqueType\_bool}’ requested  
ExactT b = FalseT();

As per my understanding, there is problem in data type of Canny edge detection filter. This filter requires  
pixel type as float. But as i am dealing with 3D series, my pixel type is signed short and constexpr unsigned int.  
Is it correct?  
I tried using castimagefilter also. but getting same error for cast image filter.

error: no matching function for call to ‘itk::CastImageFilter\<itk::Image\<unsigned char, 3\>, itk::Image\<double, 3\> \>::SetInput(itk::ImageSource\<itk::Image\<short int, 3\> \>::OutputImageType\*)’  
toReal-\>SetInput( reader-\>GetOutput() );

And another error for next filter (gradient magnitude).

I am unable to understand how to make pipeline of different filters which requires different data types for its input.  
I am using ROI, canny edge, gradient magnitude and watershed filters. And I want to use it on 3D series data as input and want 3D image as output.

Anybody has any solution for this problem?  
^

---

<div class="post-metadata">

**Author:** ![dzenanz](https://discourse.itk.org/user_avatar/discourse.itk.org/dzenanz/32/1093_2.png) [@dzenanz](https://discourse.itk.org/u/dzenanz)\
**Post date:** [June 5, 2019, 2:26pm UTC](https://discourse.itk.org/t/itk-concept-checking-error/1946/2 "2019-06-05T14:26:50Z")

</div>

Canny edge needs a float image type as output, e.g.:  
using `CannyType = itk::CannyEdgeDetectionImageFilter<ShortImageType, FloatImageType>;`. It might also need input type to be `float`. You can start from a [working example](https://itk.org/ITKExamples/src/Filtering/ImageFeature/DetectEdgesWithCannyFilter/Documentation.html) and modify it to suit your needs.