ok, novacrazy on reddit prvided a shader based solution, that works way better.
create a “custom” node and paste this HLSL code into to Code line in the details panel
return TextureObect.Load(int3(PixelIndex,0));
Set the Output Type to “CMOT Float 4” (this are the channels RGBA)
name the Input Name for the first Input to TextureObject
and add another input with the small + sign and call that input PixelIndex
Now create:
a TextureObjectParameter node and call it “SlateUI”
a TextureProperty node and set it to TextureSize
a TextureCoordinate node
a Multiply node
2 ComponentMask nodes and for the first set the checkboxe to true for R,G,B and the second one for A only
connect:
TextureObjectParameter to the TextureObject input of the custom node and to the TextureProperty node
TextureProperty and TextureCoordinate to the Multiply node
Multiply node to the PixelIndex input of the custom node
Custom node to both ComponentMask nodes (these are you final outputs RGB and Alpha)
here is the documentation on the “Load” command in the HLSL code