PapEye Mottling to produce a CD mottling profile from scanned sheets

A single mottling value describes the print uniformity of one area. When sheets are sampled from known positions across the paper web, the same measurement can also be used to create a cross-direction profile.

One PapEye customer uses this method routinely. Sheets are taken from different CD positions, kept in order and scanned as one batch. PapEye Print Uniformity applies the same measurement regions to every sheet and exports the results to CSV.

Plotting the mottling values against the original sheet positions gives a CD profile of print uniformity. This makes it easy to see whether mottling changes across the web, whether there is an edge-to-edge trend, or whether a particular position differs from the rest.

For mottling, 300 DPI scanning is sufficient: we compared 300 DPI scans against higher resolutions and the mottling values were the same. Graininess and banding are measured at a finer scale and need 1200 and 600 DPI.

This customer scans with an A3 sheet-fed scanner, an Epson WorkForce DS-30000, which makes larger batches quick to measure. A normal flatbed scanner can also be used.

The measurement requires only the sampled sheets, a scanner and PapEye Print Uniformity.