On-Line Monitoring of Postage Stamp Color at the Bureau of Engraving and Printing

This paper presents a user's viewpoint on the contribution that on-line radiometric colorimetric measurements make toward improving color consistency of postage stamps printed at the Bureau of Engraving and Printing (BEP). Color consistency of postage stamps is very critical because postage stamps receive the closest inspection among products produced by web printing processes. Through an intensive developmental program the BEP has effectively adapted large aperture colorimeters to monitor stamp color and appearance on-press, in real-time. In addition to implementing the hardware necessary to make the actual stamp color measurements, this effort also involved the introduction of color variations in terms that directly correspond to the color perception characteristics of the human visual system. As operational experience was gained with on-line color monitoring, the techniques implemented also proved very effective for generating quantitative quality profiles of finished stamp rolls. As operational experience was gained with on-line color monitoring, the techniques implemented also proved very effective for generating quantitative quality profiles of finished stamp rolls.