Patent ID: 6853736

Claim:
An image processing apparatus comprising: input means for entering an image in which predetermined information is embedded in a manner so that the predetermined information is not easily recognized visually; process means for filtering the entered image with plural filters having different characteristics respectively; detection means for detecting plural feature amounts based on conversion values obtained by said filtering; and extraction means for extracting the predetermined information, based on the detected plural feature amounts, wherein the predetermined information is embedded based on the characteristics of the plural filters, wherein said image processing apparatus further comprises (a) thinning means for executing a thinning process according to a predetermined regularity on the conversion values obtained by said filtering, and (b) adding means for adding the conversion values subjected to the thinning process by said thinning means, wherein said detection means detects the feature amounts based on a result of addition by said adding means, wherein the feature amounts are levels of scattering of the results of addition of the thinned conversion values corresponding to a change in a phase, and wherein the levels of scattering are either differences between the respective maximum values and the second largest values, or differences between the respective minimum values and the second smallest values.