[ITK-users] How to determine PixelType of itk::Image

[Lambert Zijp]

This is all very confusing to me. In the FileWriter example, the
caller *already
knows* what the IOComponentType
<http://www.itk.org/Doxygen/html/classitk_1_1ImageIOBase.html#a8dc783055a0af6f0a5a26cb080feb178>
and
what the IOPixelType
<http://www.itk.org/Doxygen/html/classitk_1_1ImageIOBase.html#abd189f096c2a1b3ea559bc3e4849f658>
of
the itk::Image is (it is hard-coded; not retrieved from the itk::Image).
The same holds for the reader: it gets that information from the file.
I want to make a general function that takes *ANY* itk::Image as input, and
converts it to an AVS datasructure (which supports all of them). So I need
to get the information from itk::Image.
Is there a way to get it from itk::Image? Or is it true that an itk::Image
does not know what it actually is/represents?

On Tue, Mar 15, 2016 at 7:07 PM, Dženan Zukić <dzenanz at gmail.com> wrote:

> If I remember correctly, using this
> <http://www.vtk.org/Wiki/ITK/Examples/IO/ReadUnknownImageType> approach
> you can also get number of components with something like:
> imageIO->GetNumberOfComponents();
> You can take a look at class documentation
> <http://www.itk.org/Doxygen/html/classitk_1_1ImageIOBase.html> for more
> details.
>
> On Tue, Mar 15, 2016 at 1:09 PM, Lambert Zijp <ljzijp at gmail.com> wrote:
>
>> I'm still not sure how to handle vector images. Dženan gave an example
>> of an RGB image. That would be a 3-vector unsigned char pixeltype.
>> Would I have to write out in those *'if  **(**typeid(ValueType) == ???)'*
>> statements all permutations of the number of vectors and the type? Or is
>> there a way to separate the number of vectors and the pixeltype?
>> How are vector images stored in memory in ITK. In an RGB image for
>> example, are the pixels consecutive triplets, or is the image stored as
>> three consecutive color planes?
>> I'm particular interested in 3D displacement vector fields, that are the
>> result of deformable registration.
>>
>>
>> On Tue, Mar 15, 2016 at 5:22 PM, Bill Lorensen <bill.lorensen at gmail.com>
>> wrote:
>>
>>> This example may help
>>> http://www.vtk.org/Wiki/ITK/Examples/IO/ReadUnknownImageType
>>> On Mar 15, 2016 8:44 AM, "Dženan Zukić" <dzenanz at gmail.com> wrote:
>>>
>>>> Of course it complained, switch statement is for integral types (if I
>>>> remember correctly).
>>>>
>>>> Regards
>>>>
>>>> On Tue, Mar 15, 2016 at 11:39 AM, Lambert Zijp <ljzijp at gmail.com>
>>>> wrote:
>>>>
>>>>> Hi Dženan,
>>>>>
>>>>> Thank you very much!
>>>>> Visual Studio 9 does not recognize decltype(), but typeid() worked
>>>>> fine. At least, when you make separate if statements, like you did in your
>>>>> example. When tried to use it in a switch statement, the compiler
>>>>> complained.
>>>>>
>>>>> Greetings,
>>>>> Lambert
>>>>>
>>>>>
>>>>> On Tue, Mar 15, 2016 at 2:47 PM, Dženan Zukić <dzenanz at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Hi Lambert,
>>>>>>
>>>>>> the classic way is using a bunch of if-else's.
>>>>>>
>>>>>> if (decltype(ValueType)==decltype(int))
>>>>>> {
>>>>>> //int specific processing
>>>>>> }
>>>>>> else if (decltype(ValueType)==decltype(itk::RGB<char>))
>>>>>> {
>>>>>> //RGB<char> specific processing
>>>>>> }
>>>>>> ​else if ...​
>>>>>>
>>>>>> ​If you can't use C++11's decltype then use typeid from <typeinfo>​
>>>>>> header.
>>>>>>
>>>>>> Regards,
>>>>>> Dženan
>>>>>>
>>>>>> On Tue, Mar 15, 2016 at 5:48 AM, Lambert Zijp <ljzijp at gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> I want to write a function that converts an arbitrary ITK image to
>>>>>>> another format (AVS in my case).
>>>>>>> It has been suggested that following functionprototype could de the
>>>>>>> job:
>>>>>>> template<typename ValueType,unsigned int Dimension>
>>>>>>> int ItkToAvs(AVSfield** ppAvs, typename
>>>>>>> itk::Image<ValueType,Dimension>::Pointer pItkImage);
>>>>>>>
>>>>>>> Now I want to know whether ValueType equals unsigned char or short
>>>>>>> or int etc. Also whether the pixels are single numbers or vectors. How does
>>>>>>> one do that?
>>>>>>>
>>>>>>> Greetings,
>>>>>>> Lambert
>>>>>>>
>>>>>>>
>>>>>>>
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>>>>>
>>>>
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