ITK/Tutorials/DOs and DONTs: Difference between revisions

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= PipeLine =
= PipeLine =


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* Do call Update() before using the pipeline output
* Do call Update() before using the pipeline output
* Do call UpdateLargestPossibleRegion() when reusing a reader.
  <PRE>
        When reusing a reader you must call:
            reader->UpdateLargestPossibleRegion()
        instead of the usual:
            reader->Update()
        Otherwise the extent of the previous image is kept, and in some cases lead to Exceptions
        being thrown if the second image is smaller than the first one.
  </pre>


= Filter-Specific =
== itkConnectedComponentsImageFilter==
=== DO NOT ===
* Do not assume InputImage->SetRequestedRegion(smallregion) will make the filter faster! The filter will run on the entire InputImage regardless.
=== DO ===
* To make it run on a smaller block:
**get a new itkRegionOfInterestImageFilter, say ROIfilter
** ROIfilter->SetInput(InputImage);
** ROIfilter->SetRegionOfInterest(smallregion);
** CCfilter->SetInput (ROIfilter->GetOutput());


= Image Creation =
= Image Creation =
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== DO NOT ==
== DO NOT ==


* Do not declare constanst using  
* Do not declare constants using  
** #define CONST_VALUE_NAME 3
** #define CONST_VALUE_NAME 3
** Use instead
** Use instead
*** const unsigned int CONST_VALUE_NAME = 3,   
*** const unsigned int CONST_VALUE_NAME = 3,   
* ITK doesn't define constants with  #defines in header files
* ITK doesn't define constants with  #defines in header files
* Do not call Delete() in an ITK smart pointer.
** If you want to destroy a smart pointer object itksmartp, do:
          itksmartp = NULL;
  the ITK smart pointer will determine whether the object should be "deleted".
  <pre> Calling Delete() in ITK smart pointers is a common mistake
        when combining VTK code (that requires the use of Delete() )
        and ITK code, (that forbids the use of Delete() ).
        Using the new vtkSmartPointer class will help in a more consistent mindset when combining ITK and VTK code.
        Instead of:
              vtkclass * ptr = vtkclass::New();
        do:
              vtkSmartPointer< vtkclass >  ptr = vtkSmartPointer< vtkclass >::New()
        and then you won't need to call Delete() in VTK classes either.
    </pre>

Latest revision as of 13:17, 1 December 2010

PipeLine

DO

  • Do call Update() before using the pipeline output
  • Do call UpdateLargestPossibleRegion() when reusing a reader.
        When reusing a reader you must call:
             reader->UpdateLargestPossibleRegion()
        instead of the usual:
             reader->Update()
        Otherwise the extent of the previous image is kept, and in some cases lead to Exceptions 
        being thrown if the second image is smaller than the first one.
   

Filter-Specific

itkConnectedComponentsImageFilter

DO NOT

  • Do not assume InputImage->SetRequestedRegion(smallregion) will make the filter faster! The filter will run on the entire InputImage regardless.

DO

  • To make it run on a smaller block:
    • get a new itkRegionOfInterestImageFilter, say ROIfilter
    • ROIfilter->SetInput(InputImage);
    • ROIfilter->SetRegionOfInterest(smallregion);
    • CCfilter->SetInput (ROIfilter->GetOutput());

Image Creation

DO

  • On a newly-manually-created image, do initialize the pixel values if you expect them to be so!
    • Example: image->FillBuffer(0); // initialize it to all dark
    • ITK doesn't initialize the image buffer when you call Allocate(). It is your responsibility to initialize the pixel values.

Coding Style

DO NOT

  • Do not declare constants using
    • #define CONST_VALUE_NAME 3
    • Use instead
      • const unsigned int CONST_VALUE_NAME = 3,
  • ITK doesn't define constants with #defines in header files
  • Do not call Delete() in an ITK smart pointer.
    • If you want to destroy a smart pointer object itksmartp, do:
          itksmartp = NULL;
  the ITK smart pointer will determine whether the object should be "deleted".
 Calling Delete() in ITK smart pointers is a common mistake
         when combining VTK code (that requires the use of Delete() )
         and ITK code, (that forbids the use of Delete() ).
         Using the new vtkSmartPointer class will help in a more consistent mindset when combining ITK and VTK code.
         Instead of:
              vtkclass * ptr = vtkclass::New();
         do:
              vtkSmartPointer< vtkclass >  ptr = vtkSmartPointer< vtkclass >::New()
         and then you won't need to call Delete() in VTK classes either.