Print Grain Index AN ASSESSMENT OF PRINT GRAININESS FROM COLOR NEGATIVE FILMS

AN ASSESSMENT OF PRINT GRAININESS FROM COLOR NEGATIVE FILMS Print Grain Index refers to a method of defining graininess in a photographic color print, typically made from a color negative. The Print Grain Index method replaces rms (root-mean-square) granularity and has a different scale which cannot be compared with rms granularity. This method is designed to be more meaningful to viewers who are accustomed to looking at prints as the end product (see “THE PRINT GRAIN INDEX METHOD”). Currently, the method applies only to color negative films. The Print Grain Index (PGI) method uses a uniform perceptual scale, with a change of two units equaling a jnd (just-noticeable difference) in graininess. A PGI rating of 25 on the scale represents the approximate visual threshold for graininess, with higher numbers indicating an increase in the amount of graininess observed. The method uses a diffusion enlarger to make prints, so Print Grain Index numbers may not represent graininess observed from more specular printing illuminants such as condenser enlargers.