1. A digital printing system, comprising: an image processor configured to generate binary printer signals that represent an encoded image inside a scan image, wherein said encoded image includes a visible representation of a presented image and has a substantially invisible representation of an original image printed among said presented image; a print channel configured to receive said binary printer signals from said image processor as a plurality of separations; an encoded image analyzer configured to obtain an encoding transformation function used to position pixels corresponding to said substantially invisible original image representation among said original image; an original image location identifier that identifies pixels in said scan image that correspond to locations of said substantially invisible original image representation and applies a decoding transformation function to said substantially invisible original image representation corresponding pixels; an original image recovery device configured to assign a selected grayscale value to each pixel of said substantially invisible original image representation identified by said decoding transformation function; and an output generator configured to generate a visible representation of said original image.