pcl::CompositionOp Namespace Reference

Image composition operators. More...

Detailed Description

The following are the Porter-Duff alpha composition operators, supported by all versions of PixInsight:

CompositionOp::Clear	Clear
CompositionOp::Source	A
CompositionOp::Destination	B
CompositionOp::SourceOver	A over B
CompositionOp::DestinationOver	B over A
CompositionOp::SourceIn	A in B
CompositionOp::DestinationIn	B in A
CompositionOp::SourceOut	A out B
CompositionOp::DestinationOut	B out A
CompositionOp::SourceAtop	A atop B
CompositionOp::DestinationAtop	B atop A
CompositionOp::Xor	A xor B

See T. Porter & T. Duff, Compositing Digital Images, Computer Graphics Vol. 18, Num. 3, July 1984, pp 253-259.

In addition, the following operators are also supported starting from PixInsight core version 1.7.0.702:

CompositionOp::Min	Min( A, B )
CompositionOp::Max	Max( A, B )
CompositionOp::Add	A + B
CompositionOp::Multiply	A * B
CompositionOp::Screen	~A * ~B
CompositionOp::Overlay	(A > 0.5) ? ~(~(2*(A - 0.5)) * ~B) : 2*A*B
CompositionOp::ColorDodge	A/~B
CompositionOp::ColorBurn	~(~A/B)
CompositionOp::HardLight	(B > 0.5) ? ~(~A * ~(2*(B - 0.5))) : A*2*B
CompositionOp::SoftLight	(B > 0.5) ? ~(~A * ~(B - 0.5)) : A*(B + 0.5)
CompositionOp::Difference	Abs( A - B )
CompositionOp::Exclusion	0.5 - 2*(A - 0.5)*(B - 0.5)

In the tables above, A represents a target pixel and B represents a source pixel. For example, if a Graphics object is being used to paint on a Bitmap object, bitmap pixels are target pixels, and any graphical elements drawn using the Graphics object are considered as source pixels.