The invention discloses a (k,n) threshold based user-friendly visual
secret sharing method and mainly solves the problems of low security and contrast in the prior art. The method is implemented by the steps of 1, performing (k,n) random grid
processing on a binary secret image S to obtain n basic shared images of random grids; 2, performing block segmentation on an input gray cover image by using
histogram equalization to obtain a
gray level equivalent to the
gray level of each small image block; 3, performing
halftone processing on the cover image subjected to the block segmentation, and according to a generated dithering matrix, obtaining a shared cover image after the
halftone processing; and 4, performing block segmentation on the generated basic shared images and cover image, performing combination according to a stacking ratio of a constant value
delta, and performing block segmentation and combination to generate a meaningful final shared image. According to the method, the
attack of attackers can be prevented, the meaningful final shared image can be generated, and the application range of visual
secret sharing can be extended.