The red,green and blue digital color values of a digital image,from a flatbed scanner,were related with optical densities,and their standard deviations were composed into graininess.

• 该方法建立了数字影像中红、绿、蓝色值与印片三色光学密度的关系,由三色数值标准偏差的平方加权组合形成颗粒性评价值。