[Insight-users] Help on getting and reading image buffer

[Luis Ibanez]

Hi Xuejun,

Please look at the code of the fltkSlicer* classes in:

    InsightApplications/
       Auxiliary/
         FltkImageViewer/
             fltkSlice2DDrawer.txx  line 344
             fltkSlice3DDrawer.txx  lines 522,611,671


They will show you how to use the gluScaleImage() method
with buffers from ITK images.


   Regards,


       Luis




----------------------------------
Xuejun wrote:
> Dear all ITK users and developers;
> 
>  
> 
> I am trying to getting the image buffer and input it into a OpenGL 
> function gluScaleImage to resize the image. Unfortunately my code does 
> not work despite my many times try. The major part of the code is listed 
> as follows:
> 
>  
> 
> ……
> 
> try
> 
>     {
> 
>                         reader->Update();
> 
>     }
> 
>             catch (itk::ExceptionObject & err)
> 
>     {
> 
>                         std::cerr << "exception in file reader " << 
> std::endl;
> 
>                         std::cerr << err << std::endl;
> 
>                         return ;
> 
>     }
> 
>  
> 
> InputImageType::Pointer image = reader->GetOutput() ;
> 
> const InputImageType::RegionType &region = image->GetBufferedRegion() ;
> 
>  
> 
> // image size
> 
> unsigned long lwidth = image->GetBufferedRegion().GetSize()[0] ;
> 
> unsigned long lheight = image->GetBufferedRegion().GetSize()[1] ;
> 
>  
> 
> // set up new size
> 
> double   factor  =  0.5 ;
> 
> int         nNewWidth = (int)lwidth * factor;
> 
> int         nNewHeight = (int)lheight * factor;
> 
> unsigned char rasterNew = new unsigned char [nNewHeight * nNewWidth] ;
> 
>  
> 
> // resize the image buffer
> 
> int iscale = gluScaleImage(GL_RGBA, (GLint)lwidth, (GLint)lheight, 
> GL_UNSIGNED_BYTE, &region, (GLint)nNewWidth, (GLint)nNewHeight, 
> GL_UNSIGNED_BYTE, rasterNew ) ;
> 
>  
> 
> But the output of the function iscale=gluScaleImage is 1285. I also 
> tried to use InputPixelType *pointer = image->GetBufferPointer();. It 
> does not work either.
> 
>  
> 
> My questions are:
> 
>  
> 
>    1. How to get and reading the buffer of the image after reading an
>       image file? Is the method in the above code correct?
>    2. What does it mean by the return value 1285 of the OpenGL function
>       (I used a DICOM image with unsigned char type and it is
>       successfully read by the code)? Is the first item (pixel format) I
>       set GL_RGBA correct? and how to fix the problem?
> 
>  
> 
> Your kind help is greatly appreciated.
> 
>  
> 
> Best regards,
> 
> Sam
> 
>  
> 
>   
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> Insight-users mailing list
> Insight-users at itk.org
> http://www.itk.org/mailman/listinfo/insight-users