[Insight-users] ScalarImageTextureCalculator

[Aster.Wardhani at csiro.au]

Hi Zachary,

I was so looking forward to read your response and try it out when I got
to work this morning. I have done (1): same result. Then I tried (2):
same result. However, the outcome made me think of using the method
SetPixelValueMinMax cause the CT image I was using has some big negative
values. Although the documentation suggested that this shouldn't be a
problem. The use of this method seems to work. I got some numbers now.
Thanks.

-----Original Message-----
From: Zachary Pincus [mailto:zpincus at stanford.edu] 
Sent: Thursday, 15 September 2005 8:23 AM
To: Wardhani, Aster (ICT Centre, e-Health Res Centre)
Cc: insight-users at itk.org
Subject: Re: [Insight-users] ScalarImageTextureCalculator

I can't give you any definitive answers without seeing the entire  
code, but here are several thoughts:

(1) Are you using the SetInsidePixelValue() method of the texture  
calculator to tell it which mask pixels correspond to regions that  
the calculator should use?

(2) Can you try a simpler case (a) without the mask image, and (b)  
without cropping the images? It would be best to try to isolate the  
problem with as simple a test case as possible.

(3) Could you send the entire code that deals with the texture  
calculations? Maybe there's a problem elsewhere not in the snippet  
below.


Zach Pincus

Program in Biomedical Informatics and Department of Biochemistry
Stanford University School of Medicine


On Sep 14, 2005, at 12:21 AM, <Aster.Wardhani at csiro.au>  
<Aster.Wardhani at csiro.au> wrote:

> Hi,
>
> I am using ScalarImageTextureCalculator to compute textural  
> features from a CT slice.
>
> I initially segment the slice using region growing. The source  
> image is then divided into blocks of say 8x8. A mask image and each  
> block (obtained using ExtractImageFilter) is fed into the  
> ScalarImageTextureCalculator but all features received are all  
> zeros. Below is a snippet of the code.
>
> ----------------------------------------------------------------------

> ------------
>
> // Extract Image Filter
>
> CropFilterType::Pointer crop_filter = CropFilterType::New();
>
> crop_filter->SetInput( _srcImage );
>
> // ScalarImageTextureCalculator
>
> textureMeasureType::Pointer texture_measure =  
> textureMeasureType::New();
>
> texture_measure->FastCalculationsOn();
>
> texture_measure->SetImageMask( _maskImage );    // label image
>
> texture_measure->SetNumberOfBinsPerAxis( 16 );
>
> texture_measure->SetInsidePixelValue( 255 );
>
> // for loop...(etc. omitted)
>
> block.SetSize( size );
>
> block.SetIndex( start );
>
>
>         crop_filter->SetExtractionRegion( block );
>
>         crop_filter->UpdateLargestPossibleRegion();
>
>         texture_measure->SetInput( crop_filter->GetOutput() );
>
>         texture_measure->Compute();
>
>         feature_vector = texture_measure->GetFeatureMeans();
>
>
>
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