Patent ID: 6418232
Filing Date: 2002-07-09
Classification: G06T

Abstract:
A method of authenticating a digital-watermark picture by execution of:an embedding process to create a digital-watermark picture as a picture obtained by embedding information for authentication into an original picture; an extraction process to extract information corresponding to said information for authentication from a picture being inspected; and an authentication process to authenticate legitimacy of said picture being inspected on the basis of said information extracted in said extraction process, wherein said extraction process comprises the steps of: carrying out geometric transformation on said picture being inspected to transform the size of said picture being inspected into a reduced scale of said original picture; creating a plurality of degraded original pictures with different types by degradation of said original picture; creating a plurality of differential pictures each representing differences between said picture being inspected with a transformed size and said degraded original pictures; and extracting information corresponding to said information for authentication from each of said differential pictures.