color restriction

I want a pure black and white colors render(no grey), like threshold option in Gimp.
But in Compositiing in Blender I can just see RGBtoBW but which is to grey in fact. But me, I want no grey.
So do you know how I could do?

You may add ColorRamp with constant option.
Edit: Work OK tested if you add the color ramp after the RGB to BW node. In my test the black area of the color ramp needs to be very small.

It’s perfect!
Thanks a lot