Assessing the Spectral Characteristics of Dye- and Pigment-Based Inkjet Prints by VNIR Hyperspectral Imaging

Abstract

Fine art photography, paper documents, and other parts of printing that aim to keep value are searching for credible techniques and mediums suitable for long-term archiving purposes. In general, long-lasting pigment-based inks are used for archival print creation. However, they are very often replaced or forged by dye-based inks, with lower fade resistance and, therefore, lower archiving potential. Frequently, the difference between the dye- and pigment-based prints is hard to uncover. Finding a simple tool for countrified identification is, therefore, necessary. This paper assesses the spectral characteristics of dye- and pigment-based ink prints using visible near-infrared (VNIR) hyperspectral imaging. The main aim is to show the spectral differences between these ink prints using a hyperspectral camera and subsequent hyperspectral image processing. Two diverse printers were exploited for comparison, a hobby dye-based EPSON L1800 and a professional pigment-based EPSON SC-P9500. The identical prints created via these printers on three different types of photo paper were recaptured by the hyperspectral camera. The acquired pixel values were studied in terms of spectral characteristics and principal component analysis (PCA). In addition, the obtained spectral differences were quantified by the selected spectral metrics. The possible usage for print forgery detection via VNIR hyperspectral imaging is discussed in the results.

Active and Low-Cost Hyperspectral Imaging for the Spectral Analysis of a Low-Light Environment

“…As depicted in Figure 10 , the spectral response of one of the leaf pairs is analyzed, which shows that a few bands are distinctively different between the printed and the real leaf. For example, the paper constituents in the printed leaf generate a notable spectral reflectance peak of around 500 nm, deviating from the spectral response of a real leaf [ 61 ].…”

“…It is clearly shown that these bands can be used to sufficiently differentiate printed and real leaves. The synthetic RGB image for printed leaves has a diverse gradient of chromatic light reflection (refer to Figure 11 ) due to the injection of fluorescent ink on the paper [ 61 ]. On the other hand, different leaves have reflections of diverse light intensity due to the varying proportions of chlorophyll [ 62 ].…”

Selection of optimal spectral metrics for classification of inks in historical documents using hyperspectral imaging data

“…It improves the spectral discriminability by making dissimilar spectra more distinctive and similar spectra more comparable. It has been used for dye and pigment in inkjet prints 27 , and for ink classification 25 .…”

“…The most common approach involves computing the average JM distance for all pairs of classes 29 . This metric has been applied to analyze dyes and pigments in inkjet prints 27 , and for ink classification 25 . In this metric, the JM and SAM algorithms are orthogonally projected by using either a sine (Eq.…”

Early esophageal detection using hyperspectral engineering and convolutional neural network

“…A hyperspectral picture is defined as an image with a spectral resolution of 10 nm or less, whereas a multispectral image refers to an image with a spectral resolution beyond 10 nm [14]. Furthermore, it is worth noting that the spectral characteristics of substances exhibit distinctiveness, hence enabling the identification of various objects [15]. This identification process may be achieved with a high level of precision by analyzing the spectral features or spectrum responses of the object or material within the acquired hyperspectral picture.…”