Technical note: A preliminary evaluation of a method for the examination of text substitutions using magneto-optical measurements.

Recent developments regarding the detection and measurement of the magnetic heterogeneity between texts produced with two different laser printers were evaluated. The present exploratory study focused on letter- and word-size fragments of texts inserted in a document to simulate the context of printed document alteration by addition. The measured values from genuine samples were used to create model arrays with the replacement or insertion of a letter or a word into the text of a base document. These model arrays were analyzed using newly introduced software features (named "induction at the point", "target", and "fragment" functions) enabling the targeted selection and isolation of small subsections of the total sensor area of the magneto-optical measuring device used in this study. It was observed that magnetic measurements of letter- or word-size fragments using the proposed methodology to the tested models allowed detection of text alterations by insertion that could not typically be detected with magnetic measurements over the full field of view of the magneto-optical device.

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