Detection of Irregularities in Regular Dot Patterns

Raster and halftone images are typically generated using small image elements, dots, which are organized and generated into a periodic structure to reproduce desired imaging effect. In this study, a periodic image element structure, referred to as a regular dot pattern, is defined, and based on the definition, two methods are introduced to detect irregularities in regular dot patterns. An example application for the methods is an automatic assessment of Heliotest sample prints. Heliotest assessment is used in the paper and printing industry to measure printability of different paper grades. In the experimental part the proposed methods are applied to detect missing elements, dots, from digitized Heliotest samples which are considered to form a regular dot pattern.