[vtkusers] Byte array from a Dicom Image

[Matias Montroull]

Why the vtkUnsignedShortArray returns a different ushort value than the one
in the image?

See the beginning of my image is: (2 bytes each pixel)

*48 248* 48 248 48 248 48 248 48 248 48 248 48 248 48 248
48 248 48 248 48 248 48 248 48 248 48 248 48 248 48 248
48 248 48 248 48 248 48 248 48 248 48 248 48 248 48 248
48 248 48 248 48 248 48 248 48 248 48 248 48 248 48 248
48 248 48 248 48 248 48 248 48 248 48 248 48 248 48 248
48 248 48 248 48 248

and vtk returns 62512 on every ushort when it should return 63536!

Can you explain why is this or am I missing something?


On Fri, Jan 24, 2014 at 10:58 PM, Matias Montroull <matimontg at gmail.com>wrote:

> One more thing, I noticed the data type is "short", so how I get the
> values in that case?
>
>
> On Fri, Jan 24, 2014 at 10:25 PM, Matias Montroull <matimontg at gmail.com>wrote:
>
>> Thanks David,
>>
>> So, I've done this and works perfect:
>>
>>                     vtkDICOMImageReader reader =
>> vtkDICOMImageReader.New();
>>                     reader.SetFileName(@"C:\DICOM\img1.dcm");
>>                     reader.Update();
>>                     vtkImageData vtkimagedata_imagen = reader.GetOutput();
>>                     vtkDataArray array_bytes =
>> vtkimagedata_imagen.GetPointData().GetScalars();
>>                     vtkUnsignedShortArray ushortArray_imagen =
>> vtkUnsignedShortArray.New();
>>                     ushortArray_imagen.DeepCopy(array_bytes);
>>                     int[] abc = new int[array_bytes.GetDataSize()];
>>                     for (int i = 0; i < array_bytes.GetDataSize(); i++)
>>                     {
>>                         abc[i] = ushortArray_imagen.GetValue(i);
>>                     }
>>
>> One more question, is it possible to re-create a Dicom Image from an
>> ushort Array?
>>
>> Thanks again,
>>
>> Matias.
>>
>>
>> On Fri, Jan 24, 2014 at 8:24 PM, David Gobbi <david.gobbi at gmail.com>wrote:
>>
>>> Hi Matias,
>>>
>>> If you have a vtkImageData object, you can get the array though
>>> VTK's abstract data set interface.  Here's an example:
>>>
>>> vtkImageData *image = reader->GetOutput();
>>> vtkDataArray *array = image->GetPointData()->GetScalars();
>>>
>>> This will return an array that contains the scalars that are
>>> associated with each point in the data.  For vtkImageData, this
>>> means the length of the array is the number of pixels in the image,
>>> so the length will be 262144 (which is 512*512).
>>>
>>> If the data is DICOM, the array will probably already be either a
>>> vtkUnsignedShortArray or a vtkShortArray (signed short).  But to
>>> be sure, you can do a conversion:
>>>
>>> vtkUnsignedShortArray *ushortArray = vtkUnsignedShortArray::New();
>>> ushortArray->DeepCopy(array);
>>>
>>> With the ushort array, you can use GetValue(i) to get one of the values.
>>>
>>>   David
>>>
>>>
>>>
>>> On Fri, Jan 24, 2014 at 3:46 PM, Matias Montroull <matimontg at gmail.com>
>>> wrote:
>>> > Hi,
>>> >
>>> > is there a way to obtain the byte array from a Dicom Image?
>>> >
>>> > I can display the image but I also need to extract the byte data, it's
>>> a
>>> > 512X512 16 bits image, so I need the Ushort array.
>>> >
>>> > Thanks!
>>>
>>
>>
>
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