[Insight-users] Cast itkImage to Matlab emxArray

[Bradley Lowekamp]

Glad to hear that it worked.

Looking at you code one more things to consider or be careful of is the case when ITK's Image BufferedRegion is not the same size as the LargestPossibleRegion. As your code does not contain any allocation, I'd hope that you have the check some place else.

Brad

On Oct 18, 2013, at 12:04 PM, Luca Tersi <lucatersi at gmail.com> wrote:

> It works like a charm.
> Thank you
> Luca
> 
> 
> ---
> ----------------------------------------------------------------------------------------------------------
> 
> 
> On 18 October 2013 17:36, Bradley Lowekamp <brad at lowekamp.net> wrote:
> Hello,
> 
> The GetBufferPointer is a method, and I would try to avoid that in a tight loop.
> 
> Here is a recent implementation to efficiently copy ITK regions:
> https://github.com/Kitware/ITK/blob/master/Modules/Core/Common/include/itkImageAlgorithm.hxx#L137
> 
> We have found that std::copy is a very robust and efficient way to copy the buffers with modern compilers. It can even work when a conversion is needed.
> 
> If you have validated the buffer is continuous and is the correct type and size. I would recommend just getting the raw buffer pointer and using std::copy. It may be up  to 10-100X faster than your implementation below.
> 
> 
> On Oct 18, 2013, at 11:28 AM, Luca Tersi <lucatersi at gmail.com> wrote:
> 
>> Hi,
>> 
>> I've included some algorithms developed with Matlab in my C++ software. The Matlab algorithms were translated to C++ using Matlab Coder.
>> I've some images that have to be passed back and forth from the itk pipeline to the Matlab algorithm that work with emxArray data type.
>> I've made the following methods in order to copy the data, but is there any better and faster method? Moreover, is it better to use iterators or access the buffer directly?
>> 
>> void ImageProcessing::CopyItkToMatlabImage(ImageProcessing::RealImageType::Pointer itkI, emxArray_real_T *matlabI)
>> {
>>   RealImageType::SizeType size = itkI->GetLargestPossibleRegion().GetSize();
>> 
>>   for (int ii=0; ii < size[0]; ++ii)
>>     for (int jj=0; jj < size[1]; ++jj)
>>       {
>>         matlabI->data[ii*size[0]+jj] = (real_T)itkI->GetBufferPointer()[ii*size[0]+jj];
>>       }
>> }
>> 
>> 
>> 
>> void ImageProcessing::CopyMatlabToItkImage(emxArray_real_T * matlabI, ImageProcessing::RealImageType::Pointer itkI)
>> {
>> 
>>   int32_T *size = matlabI->size;
>>   RealIteratorType out ( itkI, itkI->GetLargestPossibleRegion() );
>>   out.GoToBegin();
>> 
>>   for (int ii=0; ii < size[0]; ++ii)
>>     for (int jj=0; jj < size[1]; ++jj)
>>       {
>>         out.Set(matlabI->data[ii*size[0]+jj]);
>>         ++out;
>>       }
>> }
>> 
>> Thanks a lot
>> 
>> Luca
>> 
>> ---
>> ----------------------------------------------------------------------------------------------------------
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