The invention relates to a method for securing a first image by means of graphical anti-counterfeiting means and to a method for securing an identification document with such graphical anti-counterfeiting means. The invention also relates to a secure identification document that allows detecting either a fraudulent modification of the existing personalization or a fraudulent falsified document. For that, graphical anti-counterfeiting image is inserted into an identification image, each image being defined by a plurality of pixels. The characteristic level (for example grey level) of each pixel i of the graphical anti-counterfeiting image is linked, by a function F, to a matrix Ωi of pixels defined in the identification image, said pixels of the matrix Ωi surrounding the location i of a pixel of the graphical anti-counterfeiting image, said function F taking into account the characteristic level (for example average grey level) G(Ωi) and the texture level T(Ωi) of said matrix Ωi.