Category Archives: Glossary

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.

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Multispectral imaging

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Color spectrum

Color spectrum see Light spectrum

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RGB color space

A color model is a method of generating many colors from [...]

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ECI-RGB color space

The ECI-RGB V2 color space is one of the standardized RGB [...]

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Imaging techniques

In the field of art technology, imaging techniques belong to the non-invasive analysis procedures, i.e. they enable a non-destructive examination of artworks in contrast to analysis procedures in which material samples have to be removed.

These imaging methods make use of radiation of different wavelengths (from X-rays to the NIR range) and their very specific penetration and interaction with the materials of a work of art. This makes it possible to visualize material structures or differences that are invisible to the human eye.

Standard techniques include special photographic techniques such as sided light or multispectral photography. Other classic techniques, especially in the field of painting examination, include radiography, infrared reflectography  (IRR), and macro X-ray fluorescence scanning (RFA imaging), which combines imaging and material analysis.

Spectroscopy is another non-destructive analysis method.

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Multispectral imaging

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Spectroscopy

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VIS spectroscopy

VIS spectroscopy (also VIS spectrometry) is a variant [...]

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NIR spectroscopy

NIR spectroscopy (also near infrared spectroscopy or NIRS) [...]

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Ambient light

Ambient light has a significant impact on the quality of scan results.

When installing scanning systems, the calibration or color profiling of the system is done in accordance with the existing ambient light. In order to guarantee a constant scan quality, the ambient light should not be subject to strong fluctuations.

Therefore, when placing the scan systems, make sure that they are located in a room that offers constant illumination and is not subject to strong light fluctuations or direct incidence of sunlight. Placement near a window or under ceiling lighting should be avoided if possible, as this can lead to disturbing reflections.

In addition, a slightly gray-tinted room color as well as a reflection-free housing, as offered by the new scanners of the book2net Black Line, can help to ensure the scanning quality.

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White balance

The white balance adjusts the scanner’s camera to [...]

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Color profile

Every imaging device, whether a digital camera, scanner, [...]

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X71

With the book2net X71, MICROBOX has developed a unique digital camera for the digitizing sector, which is the heart of all our systems. It enables high-resolution images for a wide variety of original sizes and structures providing first-class image quality, the simplest handling and incredible speed.

  • 71 MP CMOS sensor
  • 71 million microlens system
  • Temperature regulation, control and stabilization
  • Suitable for mobile and stationary use
  • Digital focus adjustment
  • Adjustable exposure time 0.0001-2.0 sec.
  • Resolution up to 8200 dpi
  • Image transfer 0.4 sec. at 71 MP
  • Scanning time 0.2 sec. at 71 MP
  • Image transfer rate 350 Mbyte/sec. via USB 3.0 interface
  • Full screen, window and video mode

 

The all-rounder for the highest requirements: 

The modular concept of the X71 allows individual combination with standard copy stands as well as smooth integration into high-end repro systems such as the Graz Book Table or Wolfenbüttel Book Mirror.

Which documents can you digitize with the X71?
Whether loose or bound materials, fragments or large formats, glossy or matt surfaces, flat, relief or 3D objects – with the X71 you can digitize all kinds of templates in the highest quality.

Which scan formats are covered?
The distance to the object and the choice of lens determine the scan format. We offer a wide range of lenses and adapters. Our standard lens covers the formats A4 to A0; macro lenses can be used for special requirements.

Which quality standards are met?
The X71 meets the FADGI 4-star and METAMORFOZE guidelines.

Which software is used or required?
The integrated service application enables comfortable and precise system calibration. As an option, we also offer our intuitive Easy Scan Professional processing software, which provides you with advanced tools for optimal image processing. The integrated SDK also allows software from other providers to be used.

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Image sensor / CMOS versus CCD

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Multispectral imaging

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Grayscale

Grayscale is an important basis for creating a color profile and calibrating a monitor so that images appear true to color.

They are formed from the 256 colors of an RGB color palette in which the red, green and blue components remain the same in the color value. If R, G and B have the value 0, the color defined by this is a pure black; if all three color components have the value 255, this defines a pure white.

This results in a gradation of different tones between black and white, each of which is identified by a number. An intermediate value, such as 192, defines a gray color of certain brightness. In the palette of a grayscale image, therefore, all 256 colors between 0 and 255 are stored − this means that a total of 256 possible gradations in brightness can occur. All color tones, which are stored accordingly between 0 and 255, result in the different gray tones.

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Color profile

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Color management

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Delta E

Delta E (dE or ∆E) is a measurand for determining color accuracy, i.e. for quantifying the distance, colloquially difference, between a given color value and the value achieved in reproduction by print media or displays.

Since visual color perception is strongly dependent on the viewer, a quantification by mathematically measurable reference values offers the possibility of an objective evaluation.

When specifying color distances according to the dE formal, the value denotes a difference that the human eye no longer perceives.

Generally applies: the smaller the distance, the smaller the color differences. A color distance of dE <0.2 is considered invisible, a distance below dE 1.0 still as small.

Delta E is frequently used in the field of digitization as an objective measurement variable in the color profiling of grayscale and RGB primary colors for quality determination.

 

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Color profile

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Color management

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Digitization guidelines

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Color rendering index (CRI)

Color rendering is a characteristic used to define the quality of artificial light compared to natural light. The color rendering index indicates how faithfully the colors are reproduced by a light source in its own environment and how fully the light spectrum is displayed with all its color components. Compared to a natural light source, such as the sun, artificial light sources often have the problem that the color rendering deviates far from the natural light that is used as a reference.

The quality of color rendering of light sources of equivalent color temperature is described by the color rendering index (CRI).

An artificial light source would have optimal color rendering if its light contained all spectral colors as in sunlight and the colors of the illuminated objects looked correspondingly natural. In nature, perfect white is achieved when the sun falls perpendicularly on the earth at noon, i.e. no wave ranges are refracted away into the atmosphere; as a reference, this corresponds to value of CRI 100. This means that the higher the Ra value of an artificial light source, the more natural the colors appear and the higher the quality of color rendering.

With book scanners, developers try to get as close as possible to the value 100 for the light source, usually a CRI of 80-95 is achieved. However, this value is not solely responsible for the quality of the light; valid statements can only be made in connection with the color temperature. The values can also fluctuate depending on the current operating temperature of the light source.

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Color temperature

The color temperature is a measure for the quantitative description of [...]

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Light spectrum

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LED

LEDs (light-emitting diodes) are energy-saving light sources (ESL). In contrast to [...]

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Luminous intensity distribution curve

The luminous intensity distribution curve (LID) or light distribution curve is a graphical representation of the measured luminous intensity of a luminaire. In a LID, the luminous intensity in candela (cd) as well as the beam angle can be read.

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Candela

Candela (cd) is an internationally standardized physical unit [...]

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Luminous efficacy

The luminous efficacy of a light source is its efficiency or energy efficiency, which is the quotient of luminous flux (lumen) and absorbed electrical power (watt). Thus, a 100 W light bulb that delivers a luminous flux of 1500 lm has a luminous efficacy of 15 lm/W. This means that only part of the electrical power absorbed by a light bulb is converted into visible light radiation. The remaining power is mainly emitted in the infrared range and is thus detectable as thermal radiation.

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Lumen

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Candela

Candela (cd) is an internationally standardized physical unit of measurement for the luminous intensity of a light source in a certain direction.

Candela is used to describe more precisely the luminous flux emitted by a light source in a certain direction. Candela is the Latin word for candle; 1 candela therefore corresponds approximately to the amount of light emitted by a candle. Since a light source does not emit its light uniformly in all directions, another unit of measurement to lumens is necessary. While the unit of measurement lumen generally indicates the luminous flux of a light source, this value still says nothing about how focused or wide the emitted light beam is.

The candela value, which measures the intensity of light at a specific beam or solid angle, helps in this determination. An analysis of the light intensity in relation to all directions can be modeled into a so-called luminous intensity distribution curve. Depending on the design of a light source, the luminous intensity is distributed uniformly or irregularly over a given solid angle.

The higher the candela number given, the more focused the light beam. 1 candela of a light source is when its illuminance with a distance of one meter is 1 lux; i.e. lux and candela are interdependent in consequence.

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Lumen

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Lux

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