A Comparative Study of Screening Characteristics of Laser Printed Documents

Laser printers are gaining popularity in everyday work and life, but they have also become a common tool for criminal activities. Traditional document inspectors have relied on color “tracking codes” to inspect color laser-printed documents. However, recent software developments that can remove these codes have posed new challenges for document inspection. This paper presents an experimental study on the mesh characteristics of color laser-printed documents, exploring the nuances of mesh morphology, spacing, area, and angle. The research was conducted on various brands and models of printers, and different image resolutions were selected for sample production. By observing and comparing the print dot characteristics of the same section, the study aimed to uncover the underlying patterns of mesh features in laser-printed documents. The research reveals that the dot characteristics of the same laser printer exhibit relative stability across different printing time. Moreover, when the same printer is used to print images of varying resolutions, the differences in screening characteristics are negligible. Conversely, distinct brands and models of printers yield diverse dot patterns, dot spacing, dot areas, and mesh angles. Notably, the dot pattern and mesh angle characteristics serve as highly valuable identifers, particularly in the context of “same-machine” identification. This research underscores the feasibility of utilizing mesh features to differentiate laser-printed documents, thereby ofering novel inspection strategies for the authentication of color laser-printed documents.