Method for embedding and extracting multi-scale space based watermark

Abstract

A method for embedding and extracting a multi-scale space based watermark, comprises: constructing a pyramid structure of an original image by dividing each carrier image layer into M square carrier image blocks of the same size; constructing a multi-scale structure of a watermark image; embedding a watermark by embedding each watermark image into a corresponding carrier image block to obtain the original image containing the watermark; locating in the pyramid structure of the original image a target image from which a watermark will be extracted; extracting the watermark by obtaining an estimated watermark by means of the target image block and the reference image block; comparing watermarks by evaluating similarity between the estimated watermark and a watermark image to which the reference image block corresponds. Due to the multi-resolution block pyramid data structure in the present invention, a large scale attack is decomposed into a multi-level small scale attack.