Category Archives: F


Fluorescence refers to the ability of some atoms and molecules to absorb light at a certain wavelength (the excitation: Ex, excitation) and then to emit light of a longer wavelength during a short-lived emission (Em).

Art technology, among others, makes use of this property when examining works of art. Properties can be detected and assigned to specific materials; the spectrum thus becomes material-specific, a kind of optical fingerprint. The storage of such reference spectra in reference databases supports the work of scientists in their research.

False colors

Imaging techniques such as multispectral photography make it possible to convert the spectral composition of image elements on the “input side” into a different color space and thus output them as a “false color” (or false color); i.e., colors that deviate from the natural color impression are deliberately used.

An unintentional false color display can occur as a color cast, for example, if the white balance has failed.

False color imaging is based on the principle that the human eye perceives only a few hundred brightness levels of a color tone, but can distinguish about a million color shades. Therefore, a false color image uses a color scale instead of a gray scale. The color channels of the original image are assigned to other colors – for example, red to blue and blue to green. This allows individual details of the captured originals to be seen more clearly, provided that the color gradient is uniform to the eye.

In the field of art technological analysis, false color images are used to make fine nuances of a color tone or a gray level in a work of art clearly distinguishable.

Flatbed scanner

In contrast to planetary scanners, which are operating contactless with incident light, flatbed scanners work on the same principle as a copier: The original is placed on a pane of glass and light-sensitive sensors are guided under the pane of glass during scanning.

This method makes it possible to scan not only single pages and photos but also bulky documents such as books. However, in order to achieve a sharp image, the original usually has to lie flat on the glass plate. This can lead to irreparable damage to the book spine due to the high pressure load. In addition, the handling is very cumbersome as the flap has to be opened each time for the next scan; the book has to be taken out, the page turned again, etc. Likewise, this type of scanning does not allow a distortion-free and reproducible capturing of the original.

Some flatbed scanners also have a document feeder for single pages. Inexpensive flatbed scanners are therefore mainly used in office operations, where documents are mostly scanned in A4 up to A3 format.

High-priced flatbed scanners, especially in the large format area, also work with conservative LED lighting and high-resolution line sensor technology, which also enables digitization without pressure to a certain extent, but is clearly inferior to planetary scanners in terms of protection of the originals, handling and productivity.


Forensics, from the Latin forensic (belonging to the forum / market), is a collective term for scientific and technical fields in which criminal activities are systematically investigated. The history of the term originates from Roman times, during which a criminal charge meant presenting the case before a group of public individuals in the forum and defending it with facts and arguments. This origin is the source of the two modern usages of the word forensic – as a form of legal evidence and as a category of public presentation. In modern forensic science, scanning systems are used in particular to uncover forgeries of documents, certificates and works of art. This can be done primarily by using multispectral photography. It allows the non-invasive material analysis of handwriting, print and machine fonts, paper structures, color pigments, painting and drawing materials such as inks or chalks as well as the visualization of watermarks and signatures.