The nonreportable open interest in a futures market is determined by subtracting the open interest of the commercial traders plus non-commercial traders from the total open interest in that market.
Subtracting one image from the other preserves spatial information that lies between the range of frequencies that are preserved in the two blurred images.
Negative ease (i.e., "subtracting" from the body measurements) is also possible to achieve a very close-fitting look, but more than 2 inches is not recommended.