Category Archives: Glossary


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.

Focus level

We use the term “focus level” to refer to the area of a document or original that lies in the focus of the imaging unit. See also Focus.

By using area sensors in our systems, we reproduce a high depth of field. Therefore, our actual focus level is more of a three-dimensional construct, which allows for a certain degree of tolerance. So, unlike line scanners, for example, our scanners are not reduced to a fixed level.

However, it makes sense to work in the optimal focus level in order to achieve the best possible results. In order for the user to quickly recognize where this level is located, even with originals of different thicknesses or heights, LED lines indicate this area before the scan. Using the book cradle and a motorized height adjustment, the originals can be moved up or down to reduce or increase the distance to the image acquisition unit.

Book fold optimization

Some books, especially books with a thick spine, have a deep book fold when opened. When viewed from the side or front, the pages are usually very curved, making it difficult to take a true-to-scale and distortion-free image. Since our scanning systems digitize vertically from above and have a high depth of field, no information is lost despite the strong curvature. Only the text may show a slight curvature in the digital copy in such cases. This cannot be changed physically and is independent from the optics used. In order to still obtain an optimal result, our software offers the optional function “book fold optimization”. It recognizes the text and “equalizes” it so that each letter is on a straight line and the text is optimally readable. The deep book fold and the curved text are thus displayed in the best possible way.

Attention: This function is a subsequent image manipulation, which improves the optical perception, but does not match the content of the original. Basically, all our systems are designed to create a color-accurate and true digital copy of the original. Such a subsequent manipulation no longer complies with this principle.

Focus value

To set the acquisition unit to the optimum focal level, our systems offer different approaches. Depending on the original or requirement, individual focusing can thus take place. In addition to motorized autofocus or adjustment with visual support via the video mode, there is also the option of displaying a digital sharpness value.

This value is an unspecified number that becomes visible in the upper left corner of the user interface when activated. The acquisition unit or the optics can now be adjusted to find the focus. This involves a permanent measurement of the contrasts over the entire scan area. The number either increases when the image is sharpened or decreases when the image is blurred and therefore less contrast can be measured.

The goal is to find the “peak”, the point where the number is highest before it gets smaller again. If you reach this peak, you have found the optimal plane of sharpness.

The digital sharpness value is another user-friendly, supporting function for achieving an optimal scan result. It is not subject to subjective decisions, but indicates on a mathematical basis which setting is best suited for the respective original.

V lambda curve

The V lambda curve is a luminous efficiency function or luminosity function describing the average spectral sensitivity of the human eye, which it perceives in daylight. The visible spectral range from 380 to 780 nanometers is perceived as light in the human eye.


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.


LEDs (light-emitting diodes) are energy-saving light sources (ESL). In contrast to conventional light bulbs, LEDs achieve 30-50 times the lighting duration, which corresponds to about 50,000 hours. Consequently, an LED can burn for up to 2083 days or more than 5.5 years. Despite their higher initial cost, they are therefore much more economical than conventional lighting.

Our boo2net devices meet the highest conservation and ecological requirements. The Fresnel lenses specially developed for the book2net lighting units are a significant technological advantage over lighting from other manufacturers. They ensure perfect light distribution and illumination. Unwanted and disruptive gradients and reflection effects, which otherwise occur in very in very bright or very dark areas and also with glossy materials, are avoided.


Planetary scanner

As well as the term planetary scanner, the terms orbital scanner or book scanner are used to describe a category of scanners that are specifically designed for the high-quality and gentle digitization of documents and objects.

In contrast to flatbed scanners and document scanners, the scanning unit of the planetary scanner is located above the support surface, so that the originals can be scanned from above without contact. Bound originals such as books and magazines can be conveniently placed with their backs down on the scanner’s support surface. As a result, they can be opened and pages turned over normally and thus scanned very quickly and easily. In contrast to flatbed scanners, in which the book is pressed upside down on the plate and the spine is exposed to high pressure, planetary scanners are extremely gentle to the book spine.

High-quality planetary light scanners also provide adjustable book cradles, which compensate for the differences in height when turning the pages and also release the spine of the book in order to avoid any pressure. However, if a glass plate is needed such systems often also offer the possibility of an adjustable pressure control.

High-quality optics and sensor technology also guarantee the capturing over the entire surface without distortion, so that even difficult areas such as book folds and marginal areas can be easily scanned in the highest quality.

Planetary scanners are available in a wide variety of designs and formats.


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Library scanner

What are the requirements for a library scanner?

Besides archives and museums, libraries are among the main custodians of cultural knowledge. With regard to the stocks, there is certainly some overlap. Furthermore, state-sponsored public or academic libraries are service institutions that collect, develop, preserve and provide their users with access to a wide range of information on behalf of the public. Moreover, there are libraries that, like museums, have a certain collection focus or a special function (e.g. music libraries, monastery libraries, school libraries, etc.). Likewise, private libraries, e.g. of companies, religious communities, political parties, public or private associations, can be of high social importance.

The information collected in libraries is conveyed through the provision of media and services; traditionally in form of printed media such as books and journals, but increasingly also in digital form (e-books, DVDs or electronic journals). Since many printed media are often only available as single copies, access to these information carriers is usually very limited. The switch to electronic resources therefore serves to further disseminate and improve the accessibility of media, so that these are no longer limited to one or a few copies. In particular, retro digitization, i.e. the digitization of older collections and rare, valuable books, is becoming increasingly important. Many libraries make these digital copies available via e-readers as digital or virtual libraries.

The on-site use of media in libraries takes place in different ways. A basic distinction is made between lending libraries, in which media can also be physically borrowed, and reference libraries, in which media can only be used on site. Library scanners therefore increase user-friendliness, especially for reference libraries, since the media can also be used outside of the library’s own rooms via digitization.

As part of the cultural heritage, libraries are also highly threatened by disasters or as primary targets of armed conflict. Therefore, the digitization of important, historical and rare library holdings is also a form of active cultural property protection.

Due to these diverse fields of activity, libraries also need different types of library scanners when digitizing their holdings: from self-service scanners as a replacement for copiers to production scanners for document delivery services, to special scanners for retro-digitizing valuable manuscripts, from A3 to A0 large format scanners, from a simple 180° book support up to a conservational V-shape book cradle.

Therefore, self-service scanners such as our book2net Spirit A3 or book2net Public A2 are recommended for public areas with high public traffic, such as reading rooms. They offer quality, ease of use, robustness, durability and a protected operating system that cannot be manipulated. This makes them ideally suited for demanding continuous use and an environmentally friendly alternative to conventional copiers.

In contrast, the digitization centers of libraries need high-performance scanners such as the book2net Ultra A2 or the book2net Mosquito A1. V-scanners such as our book2net Cobra , Lizard and Dragon or special applications such as the book2net multispectral system for the scientific research of manuscripts and incunabula are particularly suitable for the conservational digitization of precious rare collections.

In addition to the special hardware requirements, library scanners also require special software that is intuitive on the one hand and can be easily operated by users in the self-service area, but on the other hand also meets the requirements for integrating third-party software, for supporting service offers (interlibrary loan, etc.), for OCR reading or for generating metadata.