Details:
Summary:
A paper presented at the 1991 annual TAGA meeting discussed the errors caused by failure of reflectance measuring instruments to collect all of the light reflected by translucent papers, white plastic sheets, etc. At the time of presentation, the author had recognized that placing absorbing and/or thick transparent layers on top of translucent substrates would affect the magnitude of this lateral diffusion (or translucent blurring) error; however, at that time he had not characterized the extent or mechanisms associated with these changes. The present paper investigates changes in lateral diffusion error caused by layering various transparent inks and/or plastic films on top of translucent substrates. It also looks at the effects of the top layer surface texture (e.g. matte surface plastic) of transparent overlays and the patterns (e.g. halftone screen) of ink films. These phenomena can cause errors in instrument calibration (e.g. measuring an opal glass standard) as well as measurement of graphic arts products. This error is also present in image data produced by CEPS scanners.