A print media (200) comprises paper or other substrate, on which image content, whether text or images are printed with accompanying hidden data (220). The image content is printed with one or more normal printing process visible colorants (340), while the hidden data (220) is printed with spectral edge markers (320). The spectral edge marker materials (320) have a substantial spectral absorption just outside the human visible spectrum, and only slight visible absorption, which is masked by the visible colorants (340). Although the hidden data is nominally visually imperceptible, an image capture device (250) having a visible spectral response that extends into a spectral region just outside the visible spectrum where the spectral edge marker absorption occurs, can then detect the hidden data.