ObjectPtr MedianCutSampler::doOperation( const CompoundObject * operands )
{
ImagePrimitivePtr image = static_cast<ImagePrimitive *>( imageParameter()->getValue() )->copy();
Box2i dataWindow = image->getDataWindow();
// find the right channel
const std::string &channelName = m_channelNameParameter->getTypedValue();
FloatVectorDataPtr luminance = image->getChannel<float>( channelName );
if( !luminance )
{
throw Exception( str( format( "No FloatVectorData channel named \"%s\"." ) % channelName ) );
}
// if the projection requires it, weight the luminances so they're less
// important towards the poles of the sphere
Projection projection = (Projection)m_projectionParameter->getNumericValue();
if( projection==LatLong )
{
float radiansPerPixel = M_PI / (dataWindow.size().y + 1);
float angle = ( M_PI - radiansPerPixel ) / 2.0f;
float *p = &(luminance->writable()[0]);
for( int y=dataWindow.min.y; y<=dataWindow.max.y; y++ )
{
float *pEnd = p + dataWindow.size().x + 1;
float w = cosf( angle );
while( p < pEnd )
{
*p *= w;
p++;
}
angle -= radiansPerPixel;
}
}
// make a summed area table for speed
FloatVectorDataPtr summedLuminance = luminance;
luminance = luminance->copy(); // we need this for the centroid computation
SummedAreaOpPtr summedAreaOp = new SummedAreaOp();
summedAreaOp->inputParameter()->setValue( image );
summedAreaOp->copyParameter()->setTypedValue( false );
summedAreaOp->channelNamesParameter()->getTypedValue().clear();
summedAreaOp->channelNamesParameter()->getTypedValue().push_back( "Y" );
summedAreaOp->operate();
// do the median cut thing
CompoundObjectPtr result = new CompoundObject;
V2fVectorDataPtr centroids = new V2fVectorData;
Box2iVectorDataPtr areas = new Box2iVectorData;
result->members()["centroids"] = centroids;
result->members()["areas"] = areas;
dataWindow.max -= dataWindow.min;
dataWindow.min -= dataWindow.min; // let's start indexing from 0 shall we?
Array2D array( &(luminance->writable()[0]), extents[dataWindow.size().x+1][dataWindow.size().y+1], fortran_storage_order() );
Array2D summedArray( &(summedLuminance->writable()[0]), extents[dataWindow.size().x+1][dataWindow.size().y+1], fortran_storage_order() );
medianCut( array, summedArray, projection, dataWindow, areas->writable(), centroids->writable(), 0, subdivisionDepthParameter()->getNumericValue() );
return result;
}
