Imaging technology has revolutionized the printing industry, enhancing efficiency, quality, and versatility in various printing processes, including graphic applications on 2D and 3D objects, as well as additive manufacturing (AM) or 3D printing - directly building 3D objects layer-by-layer from digital model. This paper exemplifies the applications of imaging technologies in various printing processes of 2D and 3D printing applications. In the realm of packaging printing on 2D substrates, the roles of imaging technologies are highlighted through applications in quantifying paper topography (surface roughness), ink absorption, and dynamic interactions between the print plate, the ink, and the substrate. Regarding AM or 3D printing, imaging technology is of fundamental importance enabling the entire process from digitalization of the object with 3D scanning, CAD design and visualization, to in-situ (real time) monitoring of manufacturing process, and post-production quality inspection, e.g. revealing the relationship between the variation of mechanical strength of 3D printed objects with its pore characteristics have been provided.

The Swedish research institute Innventia has taken a look into what the future needs will be for online measurements techniques in paper production. Discussions in a group consisting of experts from industry and academy, of paper and board production, measurement techniques, analysis methods and quality control systems resulted in a roadmap describing tomorrow’s needs of new applications of measurement techniques. The starting point was a vision of a high-resolution, multispectral online analysis of the complete produced area combined with new approaches for interpretation of measurements, to give better and more complete information of the paper production. One approach is to combine modern infrared (IR) imaging systems with data from the existing quality control systems in order to obtain the local grammage variation, to achieve more detailed information for optimisation of the process. The IR camera technique has been studied at the institute for 7 years, both in laboratory studies and at mills. Another online measurement technique that has been developed and studied is the online optical topography system OptiTopo. This gives information of the surface structure variation both in fine-scale and in large-scale. This instrument also gives valuable input in the quality control system. Examples from the two systems are shown.

Print through is an often encountered defect of printed maters, especially on paper grades of low and medium grammages. Print through phenomena have two contributing components, show through and strike through, resulting from insufficient paper opacity and ink penetration, respectively. The existing measurement method of print through and its components are calculated from a set of spectral reflectance values of printed and non-printed paper samples. These reflectance values are from rather big areas that equal to the opening of the employed spectrophotometer (say 33 mm in diameter). Thus, the calculated print through, show through and strike through, are only average values of the measured areas. This method has intrinsic weaknesses as paper is an inhomogeneous medium whose structure and materials compositions vary from one position to another, leading to inhomogeneous show through and strike through (opacity and ink penetration) across the measured areas, especially for papers of low and medium grammages.In this report we present a new method that enables one to take into account of variations in print through across the measured areas. The method employs a scanner that scans the printed and unprinted samples into RGB images of desired spatial resolutions. With the help of calibration patches that are simultaneously scanned as the measured samples, the RGB image signals can be converted into reflectance values. These reflectance values are then used to compute the print through, show through and strike through. Moreover, by means of Kubelka-Munk model, the depth of ink penetration at each spatial position can also be obtained. The developed method has been implemented in Matlab and successfully been applied to printed samples of newsprint and office papers. Comparative studies between instrumental measurements and perceptual evaluations confirm that the print through variations across the printed areas have strong influences on the print quality assessments. It is also found that using internal size agents in paper making is helpful for reducing ink-penetration.