[Insight-users] binary erosion

[mauro maiorca]

Hi people,
I'm trying to perform erosion with itk, but unfortunately without any
luck. The strange thing is that there isn't any problem with dilation.
starting from a volume (here a slice from the volume, the inside has
value 0, and the structure I'm interested in has value 255)
http://traversata.altervista.org/facial_segmented_28_starting.jpg
(or, if you like more png:
http://traversata.altervista.org/facial_segmented_28_starting.png )
unfortunately the result that I obtain is:
http://traversata.altervista.org/facial_segmented028.jpg
with mainly the colour reversed, and some changes far from the center
of the image. I'm using itk 3.2.0

Any help/suggestion would be appreciated!
cheers,
Mauro

The portion of code interested is:

typedef itk::Image<PixelType, 3>  outputImageType;
typedef itk::BinaryBallStructuringElement< PixelType, 3 >
StructuringElementType;
typedef itk::BinaryErodeImageFilter< outputImageType, outputImageType,
StructuringElementType >  ErodeFilterType;
ErodeFilterType::Pointer  binaryErode  = ErodeFilterType::New();

 	StructuringElementType ball;
 	StructuringElementType::SizeType ballSize;
 	ballSize[0] = 6;
 	ballSize[1] = 6;
 	ballSize[2] = 1; //I also tried with other combinations of ballSize,
but with the same results
 	ball.SetRadius(ballSize);
 	ball.CreateStructuringElement();

binaryErode->SetInput( confidence->GetOutput() );
/*confidence->GetOutput() is the image
http://traversata.altervista.org/facial_segmented_28_starting.jpg*/

binaryErode->SetKernel(  ball );
binaryErode->SetErodeValue( 255 );
binaryErode->Update();

facial_SegmentedPtr = binaryErode->GetOutput();
/*binaryErode->GetOutput() is the image
http://traversata.altervista.org/facial_segmented028.jpg*/