Category Archives: Glossary

Museum scanner

Why do museums need special scanners?

Besides archives and libraries, museums are the main custodians of movable cultural assets. With regard to the holdings, there is certainly an overlap within these institutions. The spectrum of museums and their collections is almost limitless. In addition to museums with a specific collection focus such as art, design, folklore, history, archaeology, technology and science, or a distinct specialization (e.g. architecture museum, toy museum) there are museums focusing on special functions such as museums for children or blind people.

State sponsored museums are also service institutions that collect, develop and preserve. On behalf of the public, they are supposed to undertake research and provide their visitors with as much information about their collections as possible. At the same time, such research also serves the exchange within the academic community. But also private museums, e.g. of companies, religious communities, political parties, associations or private individuals can be of high social importance due to their unique holdings.

Since museums can usually only exhibit a fraction of their collections, the presentation and communication of relevant information is increasingly taking place digitally. Virtual tours, exhibitions and annotated object databases are new communication channels. As part of the cultural heritage, museums can be massively threatened by disasters or become primary targets of armed conflicts. The thorough digitization of museum collections is therefore both a form of public information and active cultural property protection.

Due to the enormous diversity of museum holdings in general and within individual museums themselves, museums need extremely flexible scanning systems so that they do not have to purchase their own device for each requirement.

Especially in large museums of cultural and regional history, which often contain objects of all kinds, from books, cards, glass negatives to jewelry, coins, specimens, herbaria, thin rock sections through to paintings and photographs, requiring different handling, capturing and lighting technology, flexible scanning systems are indispensable.

Such systems must also meet the highest preservation requirements, since the objects to be digitized are mostly irreplaceable unique items that can be extremely fragile and light-sensitive. Museum scanners should therefore absolutely comply with internationally recognized digitization standards such as METAMORFOZE, FADGI or ISO.

We therefore offer innovative, flexible reprographic scanning systems for digitization projects in the museum and cultural heritage area. They meet the highest conservation standards and offer the greatest possible flexibility in terms of format, texture and lighting of the objects.

In addition, we have developed special applications such as the book2net multispectral system that supports scientific research.


Book formats

Book formats have changed over the centuries and vary from country to country. It is therefore necessary to have a flexible scanning system in order to be able to carefully digitize a wide variety of formats.

The book format indicates how many sheets a book printer can create from one sheet of paper, which is traditionally based on the dimensions of a Roman parchment sheet. An unfolded sheet is called an atlas format, double folio or large folio. Folding the sheet a first time provides a folio format (2 sheets), folding it a second time provides a quarto format (4 sheets), and so on. The size varied depending on the availability of the skins that were processed into parchment.

In letterpress printing from the 15th to 19th centuries, the format was also determined by the number of folds of the paper sheet. However, the size of the paper sheet varied regionally according to the respective measurement system. Sheet sizes between 20 × 30 and 30 × 40 cm were common. In addition, the book size varied by the amount of trimming after binding. The ratio of height to width varied depending on the type of folding. In the 6°, 12° and 24° formats, the width is narrower in relation to the height than in the 2°, 4°, 8° and 16° formats.

German standards

Since 1883, efforts were made in Germany to standardize sheet sizes. 12 standard formats were introduced, of which number 1 measured 33 × 42 cm unfolded. For the bibliographic description of books, the Prussian Instructions (PI) were established, which defined standardized book sizes. The old designations folio, quarto, octavo, etc. were adopted, but defined differently. Only the height of the spine was used for classification, without regard to the sheet folding and proportion, based on the space-saving library arrangement of books of the same height on shelves.

In general, formats according to PI are considerably larger than according to the traditional definition. Thus, an octavo volume according to PI is up to 25 cm high, including also quarto, octavo, duodecimo and all smaller formats according to traditional understanding. In other countries, other rules applied.

Due to different printing, binding and cutting techniques, the size of the finished book varies. Therefore, the German Library in Frankfurt a. M. has created the following guideline:



Spine Height

gr. 2°


over 45 cm


40–45 cm

gr. 4°


35–40 cm


30–35 cm

Lex. 8°


25–30 cm

gr. 8°


22,5–25 cm


18,5–22,5 cm

kl. 8°


15–18,5 cm



10–15 cm

Specification in centimeters

< 10 cm

Today, libraries in German-speaking countries mostly use the Rules for Alphabetical Cataloging (RAK) created in 1976, which are based on the International Standard Bibliographic Description (ISBD). According to this, the height of the book spine is given in centimeters during cataloging without specifying a format category. In addition to the height, booksellers and antiquaries often also specify the width of a book or a format category. The latter also applies to some foreign classification.

Digitization guidelines

Why are guidelines for digitization important to your project?:

The quality of a digitization process is subject to a wide variety of factors. It depends on components such as the scanner hardware used (sensor technology and quality of the lens), but also crucially on the light irradiation (internal, controllable lighting in the scanning system, external, often uncontrollable irradiation from natural or artificial room light). Wall colors, the color of the scanning system itself or even the clothing of the user can also influence the quality of the results. Further factors concern upstream or downstream algorithms for image processing or color management.

In particular, the digitization of valuable cultural objects should be carried out as gently and with the highest quality as possible in order to enable future generations to benefit from the data. This raises the question of the best possible concepts and methods that guarantee a constant quality of the scan results with the least physical stress. The development of and compliance with guidelines should therefore be a mandatory prerequisite for every project for the digitization of cultural property. However, navigating through the multitude of scan systems and analysis tools available on the market can be an enormous challenge for the user.

The two currently most popular digitization guidelines, which also define the relevant standards for us, come from the United States (FADGI – Federal Agencies Digitization Guidelines Initiative) and the Netherlands (Metamorfoze Preservation Imaging Guidelines – a cooperation project between the National Library and the National Archives of the Netherlands). They arose out of the need to create an objective catalog of requirements which state and public institutions can use as criteria for the procurement of scanning systems.

To standardize these two different approaches, the ISO (International Organization for Standardization) has been developing a new standard since 2012, which can be found in the three documents ISO 19262, ISO 19263 and ISO 19264. ISO 19262 documents the terms that are used in the field of image capturing in order to generate a standardized vocabulary. ISO 19263 describes the technical work processes and provides detailed information on how the measurements are best carried out. Finally, ISO 19264 describes the measurements in detail as well as goals and tolerance values for various aspects. Among other things, the main features of image quality, the metrics for evaluating these quality features, the procedure for the image quality analysis and the documentation of the results are specified.

We encourage you to review these documents in order to carry out your projects, even if you are not required to adhere to certain guidelines.

Get more information:

PDF digitization guidelines for download:


PDF digitization guidelines for download:

PDF digitization guidelines for download: Standardization of Image Quality Analysis – ISO 19264

PDF vocabulary: ISO 19262 : 2015 Photography-Archiving Systems – Vocabulary

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The Federal Agencies Digital Guidelines Initiative (FADGI) The Federal Agencies Digital Guidelines Initiative (FADGI) was founded in 2007 as a collaborative effort by different federal agencies in the United States to articulate common technical guidelines, methods and practices for the archiving of digitized and born digital documents of historical and cultural importance. These standards have been given heightened urgency by the US government’s initiative to stop the flow of analog documents into the National Archives after 2022 in favor of electronic records.

Two working groups deal with the two main themes: the audiovisual and still images. With a ranking of one (low) to four (high) stars, performance parameters were created based on a comprehensive numerical analysis of the accuracy and quality of the digital copies for varying media.

The guidelines are published and updated via

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German Federal Document Safeguarding Project

The destruction of culturally and historically significant documents through armed conflicts or natural disasters means irreparable damage to cultural memory. Valuable archive and written material are therefore particularly in need of protection. The amount of archival material and their random locations, however, generally does not allow a significant amount of outsourcing in the event of catastrophes or hazardous situations, as the protected spaces required for this are hardly available. For this reason, the Federal Republic of Germany began in 1961, in accordance with the Hague Convention for the Protection of Cultural Property, to microfilm its valuable archives for security purposes and to store them at central shelter so that they can replace the original documents in the event of irretrievable loss. The microfilming is carried out on behalf of the Federation under the leadership of the Federal Office of Civil Protection and Disaster Assistance (BBK). The archive material is security-filmed on microfilm in accordance with selection criteria defined by the Federal Government and in compliance with specified technical standards.

As part of the conversion of the microfilming devices to digital technology, which was agreed between the Federal Office for Civil Protection and Disaster Assistance (BBK) and the Conference of Heads of the Federal and State Archives Administrations (KLA), tenders for high-performance archive scanners have recently been issued to carry out this major task. We are pleased that several of the central state archives have already decided to purchase our new archive scanner book2net Archive Pro to support this project.


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Metamorfoze is the Netherlands’ national program for the preservation of paper heritage. The program is an initiative of the Ministry of OCW (Education, Culture and Sciences) and started in 1997 as a venture between the Koninklijke Bibliotheek (National Library of the Netherlands) and the Nationaal Archief (National Archives). The program is coordinated by Bureau Metamorfoze, the National Preservation Office that is situated at the National Library and counsels heritage institutions in formulating proposals for projects and carrying them out. The Bureau is also responsible for releasing information related to the program. As part of its mandate, the Bureau created guidelines for digitizing books and paper documents, which are now internationally recognized as one of the main standards. Metamorfoze is an important source of information within the international community when it comes to the mass preservation of a country’s paper heritage.

The digital images produced for Metamorfoze must adhere to specified quality standards and retain a verifiable relation to the original in such a way that they can serve as a replacement of the original object, as the originals are withdrawn from use after preservation. However, there will be different requirements for different types of material.

The Metamorfoze Preservation Imaging Guidelines are available online as a PDF document. Moreover, the Bureau Metamorfoze has also drawn up a Checklist for digitization of valuable manuscripts.

Metamorfoze describes three tiers of quality:

Low Quality

Extra Light

Mid Quality


Preservation Grade Quality

(sometimes referred to as “strict” bezeichnet)

However, the purpose of these levels is not to give a fundamentally negative judgment on digitization, which is carried out with a quality below the preservation grade quality.

There are applications in which it is completely sufficient to reach a lower level. This applies in particular to projects where the legibility of the pure text material is more important than the accuracy of the tone and color values. If the user can clearly read the result, then the quality achieved is more than sufficient for the task.

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Archive scanner

Why do archives need special scanners?

In addition to libraries and museums, archives are among the main custodians of movable cultural assets. In public ownership, they form the particularly sensitive cultural as well as the legal-administrative memory of a state, a municipality or a region. But also private archives, be it of companies, religious communities, political parties, clubs or family associations, can be of great social importance.

The information stored in archives and the associated information carriers are summarized under the term archive material. Archival records generally include documents that are no longer required by the relevant institutions, authorities, companies, organizations or private individuals for current tasks, but have been assessed as valuable for an indefinite storage. The information can be transmitted on different carriers: paper-based such as charters, documents, letters, sheet music, maps, plans, photos, electronically such as films and sound recordings, and increasingly also in digital form. Often there are also objects included such as seals or glass negatives.

What is specific to archives is that the information stored is mostly unique. Therefore, they are often subject to the protection of cultural property as part of the cultural heritage. Public archives generally work on the basis of archive laws, which define archiving and the associated fields of work as a public task. This includes the indexing, preservation of the holdings and the provision of archival materials for the community. In this context, the digitization of archival material has become increasingly important.

The complexity of archive material and the various fields of activity of archives require different systems for digitization and utilization.

Therefore, archive scanners such as our book2net Spirit A3 oder book2net Public A2 are the best solution for public areas. They offer quality, ease of use, robustness, durability and a protected operating system that cannot be manipulated.

On the other hand, archive scanners that accommodate the different formats, structures and requirements of archive material are required for digitization projects. For this purpose, we have specially developed the book2net archive scanner Archive Pro in close cooperation with our customers. This scanning system uniquely combines the qualities of a high-end book scanner with the advantages of a variable repro system, allowing the digitization of formats from A1+ to A5+ with a resolution of up to 1,200 dpi. Providing a height-adjustable camera slide, process-controlled automatic scanning and an accessible motorized support table, the system is extremely variable and user-friendly.

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PPI stands for “Pixel per Inch”. It describes the point or pixel density per inch measured at approx. 2.54 cm. The point density, also known as resolution, is an important measure for the level of detail in the reproduction of a rasterized images and one of the main quality aspects of technical reproduction processes.
The term DPI (dots per inch), which originally comes from the field of printing, is often used in this context. The DPI value describes how many dots a printer sets per inch. During the transition into the digital age and the spread of digital display devices (TV, monitor, smartphone display, etc.), the term was adapted to the pixels. Hence, both the sum of printer dots and pixels are described on 2.54 cm. Both values describe the image resolution and are used in the field of digitization to define the resolution with which an original should be scanned.

Usually round values are used, for example 150, 300, 400 and 600 ppi. However, it should be noted that a high resolution does not necessarily mean that you get a high quality image. The highest possible resolution is always recommended, but factors such as color rendering, depth of field, contrast display, possible distortion, etc. are also decisive. A good result always depends on numerous parameters. You can imagine that you use a camera once in automatic mode and then independently adjust various settings such as exposure time, aperture, white balance, etc. as you like. The resolution of the camera is always the same, but the images will differ extremely from each other. 

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In physics, the focus describes the point in an optical system where the light rays intersect after passing through the optics. At this point, therefore, the information that previously ran parallel is centered and thus fully captured. Most often, the term focus is used to mean that something is displayed in optimum sharpness. Depending on the device and the system, the determination of the focus is done selectively, centrally or point by point.

In our systems, the focus is determined over the entire scan area by means of a contrast measurement. Where the contrast is highest is the optimum sharpness plane, i.e. the focus. By looking at the entire scan area, it is ensured that the edge areas are also optimally sharp and not just the center of the original.


A filter is usually a thin transparent sheet of glass or plastic that is attached to the front of the lens to alter the image as it is taken. There are filters with specific tasks to enhance the image, and there are filters that give photographers creative options, such as color or graduated filters. The former include infrared or UV filters, which ensure that neither UV nor infrared light passes through the optics and onto the sensor, adversely discoloring the image. Polarizing filters are also often useful, as they can prevent reflections and over-illumination. This prevents information loss in said areas.

An important field of application for filters is especially multispectral photography, since filters can be used to select a wide variety of light wavelengths and bring them specifically onto the sensor.