In photomechanical reproduction, a line screen breaks the wide tonal range found in the original into discrete intervals from 1% to 99%), creating a halftone dot pattern.

• 中义在制版照相的复制过程中，用线状的平网将原稿的浓度?围分解为1%25到99%25的不连续区段，并产生半色调的网点花纹。半色调的网点值是以百分比(%25)来描述。