[Insight-users] ImageMaskSpatialObject with non unsigned char PixelType?

[Luke Bloy]

Hi Geoff,

You could file feature request at http://www.itk.org/Bug/main_page.php 
and see if it gets answered. Another option is to look into 
RescaleIntensityImageFilter 
<http://www.itk.org/Doxygen/html/classitk_1_1RescaleIntensityImageFilter.html> 
which i think will cover both the scaling issue and the conversion to 
unsigned char. Just a thought

-Luke

Geoff Topping wrote:
> Hi Luke,
>
> I considered just casting to unsigned char, but the file format I'm reading in (Analyze75) has a calibration / scale parameter that seems to get lost when casting to a signed integer type.  The absolute value of the scaled input image pixels is something like 0.001, so when cast to an integer type like signed int, or presumably unsigned char, I get all 0's.  This seems likely to cause problems when trying to use the image as a mask.  I realize this can probably be worked around as well, but having a float-compatible version of the ImageMaskSpatialObject class available by default would be much simpler and would avoid all these issues.
>
> If memory footprint becomes a problem, then it seems like that would be the time to worry about reducing it, not ahead of time by unnecessarily restricting the acceptable input to the class.
>
> Geoff
>
>   
>> Hi Geoff,
>>
>> I thought the same thing, if you template ImageMaskSpatialObject over
>> the pixeltype and it would still work. However it is pretty simple to
>> use an itkCastImageFilter.h to cast your image to unsigned char and this
>> way has a smaller memory foot print.
>>
>> -Luke
>>
>> Geoff Topping wrote:
>>     
>>> Hi,
>>>
>>> I'd like to do some masking of image registration using ImageMaskSpatialObject, but when I try to pass a
>>>
>>> itk::Image
>>>
>>> to
>>>
>>> itk::ImageMaskSpatialObject::SetImage()
>>>
>>>
>>> I get compile errors along the lines of:
>>>
>>> error: no matching function for call to `itk::ImageMaskSpatialObject::SetImage(itk::Image*)'
>>> itkImageSpatialObject.txx:281: note: candidates are: void itk::ImageSpatialObject::SetImage(const itk::Image*) [with unsigned int TDimension = 3u, TPixelType = unsigned char]
>>>
>>>
>>> This is apparently because ImageMaskSpatialObject is defined as:
>>>
>>> class ImageMaskSpatialObject
>>> : public ImageSpatialObject< TDimension, unsigned char>
>>>
>>>
>>> So I'm wondering, is there a reason ImageMaskSpatialObject can only accept images with PixelType unsigned char? (Or should it be able to take images with PixelType float?)
>>>
>>> Shouldn't it be able to work with any PixelType for which NumericTraits::Zero is valid / defined?
>>>
>>> Can I just make my own version of ImageMaskSpatialObject that instantiates its ImageSpatialObject with float instead of unsigned char, or will this cause problems?
>>>
>>> Thanks,
>>> Geoff Topping
>>>       
>
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