Abstract: The present invention provides methods and apparatus for embedding an identifying pattern of visible speckles into the digitized image of each page of a document. A speckle is a cluster of black or white pixels. Speckles are printed as black speckles on the white paper, or conversely, as areas of missing black removed from the black text characters, called white speckles. The collective pattern of all embedded black and white speckles on a single document page is called a specklemark. A specklemark can survive contrast manipulations on photocopiers and binary rasterization done by fax scanning prior to data transmission. The random pattern of the black and white speckles visible in the digitized image of a document page can be detected automatically, and by systematically matching the detected pattern with those known to have been embedded into marked copies of a document page, a specific document copy can be identified.

Abstract: The present invention provides an image watermarking technique whereby a watermark is inserted into an adjusted digital source image that is bounded by a specific bounding rectangle. If the source image is larger [smaller] than the rectangle, its dimensions are reduced [enlarged] by a common factor until it is the largest adjusted image that lies totally within the rectangle. A watermark is inserted into the adjusted image and at least one derived image of larger or smaller size is produced. Then, regardless of the size of an image derived from the watermarked adjusted image, enlarging or reducing that image to again lie within the rectangle greatly facilitates detection of the imbedded watermark. The size of the bounding rectangle may be specific to each source image, or, conversely, a common bounding rectangle may be used for a group of source images.