Characterization of Prints Based on Microscale Image Analysis of Dot Patterns

Indrama Das,Swati Bandyopadhyay,Alain Trémeau

doi:10.3390/app11146634

Indrama Das, Swati Bandyopadhyay + Show 1 more

Open Access

https://doi.org/10.3390/app11146634

Copy DOI

Journal: Applied sciences	Publication Date: Jul 20, 2021
Citations: 1	License type: CC BY 4.0

Affiliation: Jadavpur University, Laboratoire Hubert Curien

Abstract

Identifying a print document (original) from a reprint document (copy or fake) can be a challenge. The analyse at microscopic scale of print documents shows random dot shapes which depend on the printing parameters as well as the printing device used. We can, therefore, draw the assumption that the dot shapes can be used as a fingerprint to differentiate a print from a reprint. In this paper, we explore several shape indexes that were not investigated until now to analyse at microscopic scale documents printed on aluminium foils using rotogravure printing process. This paper presents a statistical analysis which is based on a pattern recognition process defined by three steps. First, a new image processing pipeline is used to segment automatically disconnected dots. Next, new dot pattern features are used to characterize automatically dot patterns. Six types of dot patterns (including four types of doughnut patterns) are introduced. Lastly, a new statistical analysis method is used to characterize a printed sample from the set of dots printed on it. The experiments done demonstrate the relevance of the analytical method proposed. Results shows the potential of this method to identify a reprint from a print.

Highlights

The objective of this paper is to explore statistically geometrical shape indexes that were not investigated until now to analyse at microscopic scale documents printed on aluminium foils using rotogravure printing process
The rotogravure printing process is not a very common printing process except for printing in large quantities, as in the printing packaging industry, especially when it comes to printing on complex surfaces such as thin aluminium foils used in pharmaceutical packaging
Our main objective was to demonstrate that the use of size and shape indexes is not not sufficient to properly characterize the shape of print dots (printed using a rotogravure notproperly sufficientcharacterize to properly the characterize the shape print dots (printed using a rotogravu sufficient to print dotsofdot, and that the categorization ofshape dots inofof predefined patterns with a process), and that the categorization dots in predefined dotcombined patterns combined with process), and that the categorization of dots in predefined dot patterns combined with a statistical analysis of relevant shape indexes is more relevant to properly characterize a print from its dots’ distribution

Summary

Introduction

The rotogravure printing process is not a very common printing process except for printing in large quantities, as in the printing packaging industry, especially when it comes to printing on complex surfaces such as thin aluminium foils used in pharmaceutical packaging. One of the main property of foils is that they are non-porous substrates, they do not cause optical dot gain. Optical dot gain happens with porous paper, due to a lateral propagation of light printed dots appear larger than their physical size [1]. Some surface irregularities or topographical depressions may be at the origin of randomly occurring small holes in printed surfaces. Similar observation was done by Hamblyn in [2] who reported a very good correlation between flexo-printed uncovered areas in dots and the location of topographical depressions in paper and paperboard surfaces

Objectives

Results

Discussion

Conclusion