Physical and Optical Behavior of Line Pairs in Graphic Arts Media

This study was made for the purpose of characterizing image sharpness through the different graphic arts media: film, plate, proof, and print. A model was proposed for evaluating sharpness with a densitometer. This paper discusses how line pairs of varying spatial frequency image in different media. Sharpness as calculated from optical measurements did not always agree with the subjective impression of edge sharpness. The reason for this can be explained by diffraction in the high frequency elements, and light scatter when measurements are made with a reflection densitometer. This paper will begin by describing the target and theory of operation. Behavior of three different films will follow. Sharpness of two photomechanical proofing systems will be compared to that of ink and paper. Finally, an attempt to use the line elements as a run control target will be described. This paper will begin by describing the target and theory of operation. Behavior of three different films will follow. Sharpness of two photomechanical proofing systems will be compared to that of ink and paper. Finally, an attempt to use the line elements as a run control target will be described.