[vtkusers] how to display RGB array/image using vtkImageImport

[Elvis Chen]

hi David,

Thanks for the quick reply.  I've put the following 3 lines into my code:


  viewer->GetWindowLevel()->SetWindow( 255.0 );
  viewer->GetWindowLevel()->SetLevel( 127.5 );
  viewer->GetWindowLevel()->SetLookupTable( 0 );

(your 1st email was sent to me only, not to vtkusers), but I still only get
black/white image.  Actually, the line that nulls the lookup table doesn't
change the grabbed image at all.  Should I not use vtkImageViewer2 at all?

h.imageRGB is an int array created using "new int [ 720x480x3 ]".  What data
scalar type should I set it to?

Elvis


On Wed, Mar 5, 2008 at 3:07 PM, David Gobbi <david.gobbi at gmail.com> wrote:

> And you might also have to set the following:
>
> viewer->GetWindowLevel()->SetWindow(255.0);
> viewer->GetWindowLevel()->SetLevel(127.5);
>
>   David
>
>
>
> On Wed, Mar 5, 2008 at 3:04 PM, David Gobbi <david.gobbi at gmail.com> wrote:
> > Hi Elvis,
> >
> >  I looked at the vtkImageViewer2 code, and it creates a default color
> >  table for you.  If you get rid of its color table, it should display
> the RGB
> >  data directly.
> >
> >  The command to get rid of the viewer's color table is as follows:
> >
> >  viewer->GetWindowLevel()->SetLookupTable(0);
> >
> >    David
> >
> >
> >
> >
> >  On Wed, Mar 5, 2008 at 2:48 PM, Elvis Chen <elvis.chen at gmail.com>
> wrote:
> >  > hello,
> >  >
> >  > I'm trying to import video/still-images from an ultra-sound machine
> and
> >  > display it using vtk.  I can grab an image from the frame-grabber and
> save
> >  > the image as PPM (basically RGB values with some headers).  The range
> of the
> >  > RGB is [0..255] and I know the dimension of the image.
> >  >
> >  > Instead of saving it to a file I want vtk to grab the array pointer
> and
> >  > display it directly.  My code looks like:
> >  >
> >  >   vtkImageImport *importer = vtkImageImport::New();
> >  >   importer->SetWholeExtent( 0, 719, 0, 479, 0, 0 );
> >  >    importer->SetDataExtentToWholeExtent();
> >  >   importer->SetDataScalarTypeToInt();
> >  >   importer->SetNumberOfScalarComponents( 3 );
> >  >   importer->SetImportVoidPointer( h.imageRGB );
> >  >
> >  >   vtkImageFlip *flip = vtkImageFlip::New();
> >  >    flip->SetInputConnection( importer->GetOutputPort() );
> >  >   flip->SetFilteredAxis( 1 );
> >  >
> >  >   vtkImageViewer2 *viewer = vtkImageViewer2::New();
> >  >   viewer->SetInputConnection( flip->GetOutputPort() );
> >  >    viewer->SetZSlice( 0 );
> >  >
> >  >
> >  > where h.imageRGB is a pointer to integer array whose size is
> 720x480x3.  The
> >  > RGB are stored as [R0 G0 B0 R1 G1 B2 ... ] in h.imageRGB.  The first
> pixel
> >  > is on the top-left corner so I need to use vtkImageFlip to get the
> correct
> >  > orientation.
> >  >
> >  > The resulting image displayed fine except for the colour.  It looks
> like a
> >  > gray-scale image where as the original US image has come coloured
> region.
> >  > Can someone please shed some light into what might be wrong?  Is
> there a
> >  > function to get the range of pixel value (to 0 to 255)?
> >  >
> >  > Any help is very much appreciated,
> >  >
> >  > Elvis
> >  >
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