"adjustable threshold" look
To answer a question in the PicMonkey group about Picnik's Adjustable Threshold feature:
You can use the Curves tool in PicMonkey to produce the same "look" as the Adjustable Threshold tool in Picnik.
Set the color override to 100% to remove all color, then set the curve to this shape. You can alter the amount of black/white by moving the vertical line to the left or right.