Image processing technology embeds signal (e.g., digital watermarks) within imagery during a raster image process(or). One claim recites: an image processing method of embedding a signal within imagery using raster image processing (RIP), including: obtaining a plurality of elements representing a signal; determining edges within the imagery; using the determined edges as a reference, modulating a plurality of print structures within the RIP according to the plurality of elements to embed the signal within the imagery, in which one determined edge defines the signal to be at a predetermined angle in a set of dimensions comprising color and spatial frequency. Of course, other claims, combinations and technology are described too.