ImageWriter

VTKExamples/Cxx/IO/ImageWriter


Description

A generic function WriteImage() is provided that selects what image writer to use based on the file extenstion and then writes the render window to the file. The following formats are supported: BMP, JPEG, PNM, PNG, PostScript, TIFF.

If no file extension is specified, PNG is assumed.

The function WriteImage() is also available in the Snippets.

Code

ImageWriter.cxx

#include <vtkActor.h>
#include <vtkNamedColors.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>
#include <vtkSphereSource.h>

#include <vtkBMPWriter.h>
#include <vtkImageWriter.h>
#include <vtkJPEGWriter.h>
#include <vtkPNGWriter.h>
#include <vtkPNMWriter.h>
#include <vtkPostScriptWriter.h>
#include <vtkTIFFWriter.h>
#include <vtkWindowToImageFilter.h>

#include <array>
#include <locale>
#include <string>

namespace
{

/**
*  Write the render window view to an image file.
*
*  Image types supported are:
*    BMP, JPEG, PNM, PNG, PostScript, TIFF.
*  The default parameters are used for all writers, change as needed.
*
*  @param fileName The file name, if no extension then PNG is assumed.
*  @param renWin The render window.
*  @param rgba Used to set the buffer type.
*
*/
void WriteImage(std::string const& fileName, vtkRenderWindow* renWin,
                bool rgba = true);
}

int main(int, char* [])
{

  vtkSmartPointer<vtkNamedColors> colors =
    vtkSmartPointer<vtkNamedColors>::New();

  // Set the background color.
  std::array<unsigned char , 4> bkg{{26, 51, 102, 255}};
    colors->SetColor("BkgColor", bkg.data());

  // Create the rendering window, renderer, and interactive renderer.
  vtkSmartPointer<vtkRenderer> ren = vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renWin =
    vtkSmartPointer<vtkRenderWindow>::New();
  renWin->AddRenderer(ren);
  vtkSmartPointer<vtkRenderWindowInteractor> iren =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  iren->SetRenderWindow(renWin);

  // Create the source.
  vtkSmartPointer<vtkSphereSource> source =
    vtkSmartPointer<vtkSphereSource>::New();
  source->SetCenter(0, 0, 0);
  source->SetRadius(5.0);

  // mapper
  vtkSmartPointer<vtkPolyDataMapper> mapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputConnection(source->GetOutputPort());

  // actor
  vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);

  // color the actor
  actor->GetProperty()->SetColor(colors->GetColor3d("Yellow").GetData());

  // assign actor to the renderer
  ren->AddActor(actor);
  ren->SetBackground(colors->GetColor3d("BkgColor").GetData());

  renWin->Render();

  std::vector<std::string> ext = {{""},      {".png"}, {".jpg"}, {".ps"},
                                  {".tiff"}, {".bmp"}, {".pnm"}};
  std::vector<std::string> filenames;
  for (auto e : ext)
  {
    filenames.push_back("ImageWriter" + e);
  }
  filenames[0] = filenames[0] + '1';
  for (auto f : filenames)
  {
    WriteImage(f, renWin, false);
  }

  iren->Initialize();
  iren->Start();

  return EXIT_SUCCESS;
}

namespace
{

void WriteImage(std::string const& fileName, vtkRenderWindow* renWin, bool rgba)
{
  if (!fileName.empty())
  {
    std::string fn = fileName;
    std::string path;
    std::string ext;
    std::size_t found = fn.find_last_of(".");
    if (found == std::string::npos)
    {
      path = fn;
      ext = ".png";
      fn += ext;
    }
    else
    {
      path = fileName.substr(0, found);
      ext = fileName.substr(found, fileName.size());
    }
    std::locale loc;
    std::transform(ext.begin(), ext.end(), ext.begin(),
                   [=](char const& c) { return std::tolower(c, loc); });
    vtkSmartPointer<vtkImageWriter> writer =
      vtkSmartPointer<vtkImageWriter>::New();
    if (ext == ".bmp")
    {
      writer = vtkSmartPointer<vtkBMPWriter>::New();
    }
    else if (ext == ".jpg")
    {
      writer = vtkSmartPointer<vtkJPEGWriter>::New();
    }
    else if (ext == ".pnm")
    {
      writer = vtkSmartPointer<vtkPNMWriter>::New();
    }
    else if (ext == ".ps")
    {
      if (rgba)
      {
        rgba = false;
      }
      writer = vtkSmartPointer<vtkPostScriptWriter>::New();
    }
    else if (ext == ".tiff")
    {
      writer = vtkSmartPointer<vtkTIFFWriter>::New();
    }
    else
    {
      writer = vtkSmartPointer<vtkPNGWriter>::New();
    }
    vtkSmartPointer<vtkWindowToImageFilter> window_to_image_filter =
      vtkSmartPointer<vtkWindowToImageFilter>::New();
    window_to_image_filter->SetInput(renWin);
    window_to_image_filter->SetScale(1); // image quality
    if (rgba)
    {
      window_to_image_filter->SetInputBufferTypeToRGBA();
    }
    else
    {
      window_to_image_filter->SetInputBufferTypeToRGB();
    }
    // Read from the front buffer.
    window_to_image_filter->ReadFrontBufferOff();
    window_to_image_filter->Update();

    writer->SetFileName(fn.c_str());
    writer->SetInputConnection(window_to_image_filter->GetOutputPort());
    writer->Write();
  }
  else
  {
    std::cerr << "No filename provided." << std::endl;
  }

  return;
}
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(ImageWriter)

find_package(VTK REQUIRED)
include(${VTK_USE_FILE})

add_executable(ImageWriter MACOSX_BUNDLE ImageWriter.cxx )

target_link_libraries(ImageWriter ${VTK_LIBRARIES})

Download and Build ImageWriter

Click here to download ImageWriter and its CMakeLists.txt file. Once the tarball ImageWriter.tar has been downloaded and extracted,

cd ImageWriter/build 

If VTK is installed:

cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

make

and run it:

./ImageWriter

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.