Lexmark Optra S 1620 User's Guide (7.1 MB) - Page 359

Enhancing Print Quality Appendixes Halftones Gray-scale objects (such as photographs) whose gray dots have been converted to a pattern of groups of black dots. These groups, which are of various sizes, along with the white dots (pixels turned off), create the illusion of gray shadings: larger groups make the image appear black or dark gray, while smaller groups make the image appear light gray. Screen Frequency The distance between the centers of the groups of black dots, measured in lines per inch (lpi); although the group size varies in a halftone image, the screen frequency remains constant. Print Quality Overview Use the following diagram as an easy guide to help you select the optimum print quality for your application. Enhancing Print Quality 343