Method QuantizeImage

Filters/Hybrid/vtkImageToPolyDataFilter.cxx:436–514

The following are private helper functions----------------------------------

// The following are private helper functions----------------------------------
//
vtkUnsignedCharArray* vtkImageToPolyDataFilter::QuantizeImage(
  vtkDataArray* inScalars, int numComp, int type, int dims[3], int extent[4])
{
  int numPixels, i, j, idx, id;
  vtkUnsignedCharArray* pixels;
  unsigned char *ptr, *ptr2, *outPixels;
  unsigned char* inPixels;

  // doing a portion of the image
  numPixels = (extent[1] - extent[0] + 1) * (extent[3] - extent[2] + 1);
  pixels = vtkUnsignedCharArray::New();
  pixels->SetNumberOfValues(3 * numPixels);
  outPixels = pixels->GetPointer(0);

  // Figure out how to quantize
  //
  if (this->ColorMode == VTK_COLOR_MODE_LINEAR_256)
  {
    // Check scalar type
    if (type != VTK_UNSIGNED_CHAR || numComp != 3)
    {
      vtkErrorMacro(<< "Wrong input scalar type");
      return nullptr;
    }
    else
    {
      inPixels = static_cast<vtkUnsignedCharArray*>(inScalars)->GetPointer(0);
    }

    // Generate a color table used to quantize the points
    //
    if (this->GetMTime() > this->TableMTime)
    {
      this->BuildTable(inPixels);
    }

    for (id = 0, j = extent[2]; j <= extent[3]; j++)
    {
      for (i = extent[0]; i <= extent[1]; i++)
      {
        idx = i + j * dims[0];
        ptr = inPixels + 3 * idx;
        ptr2 = outPixels + 3 * id;
        const unsigned char* color = this->GetColor(ptr);
        ptr2[0] = color[0];
        ptr2[1] = color[1];
        ptr2[2] = color[2];
        id++;
      }
    }
  } // using build in table

  else // using provided lookup table
  {
    if (numComp != 1 || this->LookupTable == nullptr)
    {
      vtkErrorMacro(<< "LUT mode requires single component scalar and LUT");
      return nullptr;