Category Archives: M

Margin area

When digitizing with planetary scanners, the margin area of the documents is of crucial importance.

Experience has shown that the sharpness of scans decreases towards the edge. Special lenses are therefore needed to ensure that documents and originals are uniformly sharp across the entire imaging area, i.e. not only in the center but also in the critical edge areas.In addition, distortions or color fringes sometimes occur in the peripheral areas.

To prevent this, all our systems are equipped with apochromatic corrected industrial optics designed specifically for digitization.

Megapixel

The term megapixel comes from the field of digital photography and describes the sum of the available image points (pixels) on a sensor. A megapixel stands for 1 million pixels. Basically, it can be said that a high number of megapixels also stands for a higher resolution of the images or scans. However, you have to note that several factors naturally have an influence on both the quality and the resolution. For example, appropriate lenses are necessary in order to be able to bring the quality to the sensor through the optics. It must also be taken into account that the resolution of the scan or the image always depends on the distance between the lens and the original as well as on the focal length, pixel size and the relationship between the sensor format and the original format. Commercially available consumer cameras usually have a possible resolution of 20-30 megapixels.

For our scan systems we only use our in-house developed and produced X71 camera. As the name suggests, this is a camera with a 71 million pixels sensor. In addition, the camera is equipped with a special lens and designed for the highest demands of scanning documents.

Motorized focus

What are the advantages of a motorized focus?

Our systems work with a fixed focal length as standard. This has the advantage that there is no permanent change in focus during scanning, as is the case with the autofocus systems of commercially available consumer cameras, for example. Thus, the constant size of the scans is guaranteed and a continuous mechanical wear movement is avoided.

We also equip some of our flexible systems additionally with a motorized focus that can be adjusted to different formats at the push of a button. This ensures that the focus is set correctly for each template without having the disadvantages of a classic autofocus.

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Machine vision

In addition to conventional and artistic photography, there is the large field of industrial photography, for which special machine vision cameras are designed. This segment has developed very strongly in recent years and has become the innovation engine for sensor technology.

By now, 9 billion sensors are manufactured annually, with growth rates of about 20% per year. With such volumes, competition is intense, as is innovation.

Key features:

  • A wide range of different sensors in terms of the number of pixels
  • The demand for fast sensors is growing strongly.
  • The fastest ones can now process 30000 images per second.
  • Only CMOS sensors are used; power consumption and heat generation are much better. Mechanical shutters are no longer necessary.
  • Unlike in artistic photography, emphasis is placed on uniform sharpness over the entire surface.
  • Cost-intensive innovations can only be justified with the corresponding quantities, which only this market makes possible. But these are also made.
  • Machine vision cameras serve only a specific purpose and task.

book2net X71 digital camera

Fields of application:

  • Security technology, surveillance
  • Automotive industry
  • Production monitoring
  • Scientific photography
  • Cell phones
  • Aerospace
  • Robotics
  • Gaming

Machine vision cameras are generally well-suited for tasks in the cultural sector if equipped appropriately; image quality, performance, and price are in harmony.

The innovation cycles are pleasingly short.

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.

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Metamorfoze

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

Light

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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Mechanical book cradle 180°

In a mechanical book cradle, the necessary balancing movement takes place via a mechanical lever and spring-based design. Based on the principle of a balance, such book cradles perform the lateral balancing in a self-adjusting manner. Depending on their basic mechanical design, they are usually extremely robust and durable.

Book cradles based on this concept are usually used in scanners up to A2+ format, which are often used as a replacement for copying systems in administration, in the open access area of libraries or in archive digitization.

However, since the compensating movement takes place permanently with this concept, such book cradles in professional systems also have a so-called book cradle lock. This works like a brake that prevents the book cradle from moving during the scan and thus prevents blurring. In addition, there is often also the option of locking the book cradle as a whole by hand or foot switch and using it only as a flat support table.

Such a book cradle also offers the possibility of so-called book spine exemption. This is a mechanism that opens a gap several centimeters wide between the book plates, into which the spine can be gently inserted.

Another option that such book cradles very often have are scan triggers on the document table. These offer an enormous advantage, especially when digitizing without a pressure plate. The user is thus able to trigger the scan comfortably by hand, even if he needs one hand to hold or press down the template. In professional systems, the scan triggers are integrated into the support plates of the book cradle in such a way that they are easy to operate regardless of the size, thickness or position of the originals and without damaging them.

Glass plates or Makrolon pressure plates are further optional features of such book cradles that can be used if the pages of the template are to be pressed down gently and carefully.

Advantages:
– Robust and durable
– Easy to handle
– A wide range of features for professional systems, such as automatic locking during scanning
– Locking of the book cradle by switch to the fixed support table
– Optional book spine release
– Scan trigger on the support plates of the book cradle
– Pressure aid made of glass or Makrolon©

 

Disadvantages:
– With most suppliers, the book thicknesses which can be processed are designed for height adjustment up to a maximum of 10 cm.
– • The maximum permissible weight of books for which the compensating movement still functions according to the principle of a scale is limited to a few kilograms

 

Moiré

When digitising, you might have come across strange rainbow patterns. These patterns are known as moiré (from French moiré [mwaˈʀe], “moiré, marbled”) and can cause many headaches. In this article, we will look at what moiré is and what causes it.

The moiré effect occurs when the item being captured contains a detailed pattern that does not play along with the pattern of the imaging sensor. With two separate patterns overlaid on top of each other, a third, false pattern emerges in the form of ‘moiré pattern’.

Moiré effect

Source: Wikimedia Commons Copyright: Public Domain

The moiré effect can be clearly seen in the image below: The periodic structures of the sensor are superimposed on those of the brick pattern on the building, forming a peculiar striped pattern.
Source: Wikimedia Commons (unchanged) Schloß Lötzen mit Drehbrücke im April 2012 Copyright: Colin Pelka Public Domain

Zamek w Giżycku- exterior view
Maudsley Petrol Locomotive 1904

Source: Wikimedia Commons (unchanged) Copyright: Public Domain

The moiré effect also often is a challenge when digitising newspapers since in newspaper production halftone used for photos to be printed, especially on more absorbent papers like newsprint. Since ink on newsprint dries by absorption, photos are made of varying size dots in a coarse pattern. When you made an image of the halftone image, the conflicting dot patterns resulted in a moiré pattern.

How to avoid the moiré effect

Sometimes it is already sufficient to slightly change the position or angle of the original on the scanning surface to reduce moiré. However, nowadays most image sensors are equipped with low-pass filters to filter out certain interfering components in the image signal and to block excessive spatial frequencies for the sensor.This low-pass filtering can either be implemented using an optical component in the beam path or can be achieved through electronic signal post-processing.

Another way to reduce moiré is so-called oversampling. The number of pixels is increased compared to the resolution of the output image. This increases the sampling frequency, so to speak, so that there are fewer artifacts and the limit frequency of the sensor is higher than the smallest displayable element.