Abstract: Inspired by quantum theory, a principle of self-adapted median filtering based on quantum measurement and collapsing is proposed in this paper. The pixels in the window using for median operation are presented by superposition of states of quantum mechanics. The scale of this window can be adjusted through operating on it by a measurement operator produced according to character of pixels in the window. A method using for producing the measurement operator is given here. It is shown that better result can be given by using this self-adapted median filtering compared with traditional median filtering by computer simulation.