[ITK] Binary Dilate/Erode filter

[Matt McCormick]

Hi Jay,

The region will be padded by the radius. The cropping will possibly
shrink the region at the input image's boundaries.

HTH,
Matt

On Mon, May 29, 2017 at 12:54 PM, jay nanavati
<jaysnanavati at hotmail.co.uk> wrote:
> Hi - Looking at
> ITK\Modules\Filtering\BinaryMathematicalMorphology\include\itkBinaryErodeImageFilter.hxx,
> I am a bit confused with regards to the padding and cropping of the regions
> for example, in the snippet below:
>
> ypename TInputImage::RegionType tmpRequestedRegion = outputRegion;
>   typename TInputImage::RegionType paddedInputRegion =
>     input->GetBufferedRegion();
>   paddedInputRegion.PadByRadius(radius);   // to support boundary values
>   InputSizeType padBy = radius;
>   for ( i = 0; i < KernelDimension; ++i )
>     {
>     padBy[i] = ( padBy[i] > kernel.GetRadius(i) ? padBy[i] :
> kernel.GetRadius(i) );
>     }
>   tmpRequestedRegion.PadByRadius(padBy);
>   tmpRequestedRegion.Crop(paddedInputRegion);
>
> It appears that tmpRequestedRegion is padded but then immediately cropped,
> which means it will always be padded by a radius of 1 in each dimension
> anyways? Similar operations are performed when padding the
> inputRegionForThread:
>
> // Pad the input region by the kernel
>   inputRegionForThread.PadByRadius( kernel.GetRadius() );
>   inputRegionForThread.Crop( input->GetBufferedRegion() );
>
> It would be great if someone could guide me on this.
>
> Thanks,
> Jay
>
>
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