A method for providing digital watermarking for text or images that uses spectral edge marking materials (320) printed on a print media (200) to embed hidden data (220). The spectral edge markers (320) have an absorption spectrum at the edge of the human visible spectrum, either at the UV edge or IR edge, which provides an optical density that is generally imperceptible to humans, but which can be detected by an image capture device (250). The crosstalk of visible optical absorption provided by these materials is largely masked by the presence of visible colorant(s) (340), with only small color differences between areas with and without the spectral edge markers (320). The image capture device (250) has a visible spectral response that extends into a spectral region just outside the visible spectrum where the spectral edge marker absorption occurs, and can be operated to detect the hidden data.