Application of Digital Image Analyses to Measure Print Quality

By William Lim, Suresh Mani

An important aspect of poor print quality in high-speed printing is color density variation in solid print areas, which is described as mottle. Armel and Wise provide a more detailed description and the various types of mottle.¹ Traditionally, these variations were assessed by visual side-by-side comparisons.

These assessments were influenced by subjective factors of human vision, such as fatigue and variations in color interpretation between different people.

Therefore, an objective method of mottle measurement was needed to identify the sources of mottle and plan corrective action. In recent years, personnel at Heidelberg Web Press developed the concept of an absolute scale by selecting representative samples at various levels of mottle.