Translucency issue

**expanding

Thank you for the answer,

I thought it would be the gray transition freom the white to the black. But If I draw a square it should not do it right? But it does.

The issue is that heart alpha is from the Painter software itself. 

The only way I was able to counter that was expecting pixels of the colo and keeping the mask as it was.

It looks like the anti-aliasing on the mask. If you cook closely at the mask you will see that every pixel is not either black or white. The edge pixels, between those two areas, are grey. This is done to smooth the mask edges, otherwise you would get hard pixellated edges. Those grey mask pixels though, make the mask semi-transparent at those points. So you get a mix of the opaque red and semi-transparent green under those grey pixels.

The impact will be reduced by working in a higher resolution and ensuring your mask edges are made with a hard brush, but it will still be there. If you were to remove all anti-aliasing (using a levels filter) then there would be no green showing, but you would have pixellated edges instead of smooth curves.

Dave