Left Toolbar > Math Nodes > Rgbo Element
The RGBO Element node provides each channel information as an output. RGBO output: Red Green Blue Opacity.
On the left toolbar choose Point Nodes > Point Rgbo Element
Drag the Rgbo Element icon into the Node Graph.
Connect the Output .
rgbo A RGBO type.
This attribute is exposed as input by default. Right-click the Node to hide this attribute as input and set the point values manually. Default R:0.0, G:0.0, B:0.0, O:0.0