[Insight-developers] [Insight-users] Interpolation and resampling templates

[Emmanuel Christophe]

Hi all,
I'm coming back on this issue. Since that time, I opened a bug on ITK
mantis to be able to follow:
http://www.vtk.org/Bug/view.php?id=9243

We've been using the patch I submitted in the ITK version we include
in OTB (www.orfeo-toolbox.org) for a while, but it would make more
sense to integrate it in ITK (this would enable the OTB users to use
their own external version of ITK, that would greatly easy the process
of updating the internal ITK, etc).

I'm ready to rework the patch to avoid modifying the NumericTraits. I
agree with Brad statement that the function is misplaced. However, I
don't know what would be the best way to replace the operation
sequence

        if( value < minOutputValue )
          {
          pixval = minValue;
          }
        else if( value > maxOutputValue )
          {
          pixval = maxValue;
          }
        else
          {
          pixval = static_cast<PixelType>( value );
          }
(see l346-359 of Code/Review/itkOptResampleImageFilter.txx but also in
4 other places at lines 410, 474, 689 and 730 and in file
Code/BasicFilters/itkResampleImageFilter.txx at line 284 and 463).

The idea would be to make this sequence valid for std::complex as
well. Once the template are sorted out between the type of the value
and the type of the coordinates (the first part of the patch), these
operations are the only thing that prevent a correct usage of the
registration framework on complex data.

Let me know what you think,
Emmanuel



2009/3/6 Bradley Lowekamp <blowekamp at mail.nih.gov>:
>
> On Mar 6, 2009, at 8:29 AM, Karthik Krishnan wrote:
>
> On Fri, Mar 6, 2009 at 2:13 AM, Emmanuel Christophe
> <emmanuel.christophe at gmail.com> wrote:
>>
>> Hi Karthik, Brad,
>>
>>
>> - Not sure if NumericTraits is the best place for the Clamp function.
>> I put it there as it is closely related to the type and in the case of
>> the itk::ResampleImageFilter is used as a precaution before a
>> static_cast. I haven't defined it for Vectors, RGB etc.
>
> Thanks for the patch.
>
> I think its  good to define it for all pixel types for which it makes sense.
>
> I am not disagreeing with the usefulness of the clamp function. I just
> disagreeing with the adhoc adding of a function to the NumericTraits class.
> Clamp is not a trait is a function which is rather different then how this
> class is currently designed.
> If we did want to add a set of functions it would be great and useful
> (where?). I would think that Min, Max and LERP should be considered. I just
> think some consideration should be made to what it means to all pixel types.
> And they need to be made consistent across all traits where appropriate. The
> NumericTraits class is a little bit of a pet peeve of mine. I think is needs
> a more design and documentation to flush things out between everything, and
> some careful review. :)
>
>
>
>> - I don't think the itk::ResampleImageFilter was able to resample RGB
>> images. At one point it would have tried to compare two RGBPixel using <.
>
> Right. One would have to use the VectorResampleImageFilter.
>
> Yes, this is how I have done it. Sorry for my confusion. RGBPixel type does
> in fact have a operator<, but the meaning and usefulness is debatable.
> Sorry for being difficult on this subject :)
> Brad
>
>