Function merge

src/IECoreImage/HdrMergeOp.cpp:156–211

template< typename T >
inline void merge( bool firstImage, size_t &pixelCount,
					const ImagePrimitive * img, ImagePrimitive * outImg,
					const Imath::Box2f &windowing, float intensityMultiplier,
					FloatVectorData * outR, FloatVectorData * outG, FloatVectorData * outB, FloatVectorData * outA )
{

	const TypedData< std::vector< T > > *inR = img->getChannel< T >( "R" );
	const TypedData< std::vector< T > > *inG = img->getChannel< T >( "G" );
	const TypedData< std::vector< T > > *inB = img->getChannel< T >( "B" );

	if ( firstImage )
	{
		pixelCount = inR->readable().size();
		outR->writable().resize( pixelCount, 0 );
		outG->writable().resize( pixelCount, 0 );
		outB->writable().resize( pixelCount, 0 );
		outA->writable().resize( pixelCount, 0 );
		outImg->setDisplayWindow( img->getDisplayWindow() );
		outImg->setDataWindow( img->getDataWindow() );
	}
	else
	{
		if ( pixelCount != inR->readable().size() ||
			 pixelCount != inG->readable().size() ||
			 pixelCount != inB->readable().size() )
		{
			throw Exception( "Images are not of the same resolution!!" );
		}
	}

	const T *ptrInR = &(inR->readable()[0]);
	const T *ptrInG = &(inG->readable()[0]);
	const T *ptrInB = &(inB->readable()[0]);
	float *ptrOutR = &(outR->writable()[0]);
	float *ptrOutG = &(outG->writable()[0]);
	float *ptrOutB = &(outB->writable()[0]);
	float *ptrOutA = &(outA->writable()[0]);

	for ( size_t i = 0; i < pixelCount; i++ )
	{
		float intensity = (*ptrInR + *ptrInG + *ptrInB) / 3.0;
		float weight = smoothstep( windowing.min[0], windowing.min[1], intensity );
		if ( !firstImage )
		{
			weight *= 1.0f - smoothstep( windowing.max[0], windowing.max[1], intensity );
		}
		float m = weight * intensityMultiplier;
		*ptrOutR += *ptrInR * m;
		*ptrOutG += *ptrInG * m;
		*ptrOutB += *ptrInB * m;
		*ptrOutA += weight;

		ptrInR++; ptrInG++; ptrInB++;
		ptrOutR++; ptrOutG++; ptrOutB++; ptrOutA++;
	}
}

ObjectPtr HdrMergeOp::doOperation( const CompoundObject * operands )