IT / EN
AREAW4
(printing process)
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AreaW4 is a high-performance offset printing process that can reproduce up to 520,000 tones in four-color printing (40 percent more than the requirements of the ISO standard). Conceived by Trifolio to produce books of superior quality, it is an “open” process, continually and rapidly evolving, that skillfully unites the intuition and knowledge of its developers with advances in technology. AreaW4 is a workshop of innovative ideas, an advanced research department, and a results-oriented production facility. Trifolio guarantees its clients a print quality that stands out within the panorama of art publishing.

Color theory is a branch of optics that studies the classification of colors and their perception by the human eye. Color is a physical phenomenon that we perceive thanks to three fundamental conditions:


  1. light;
  2. the physical properties of the material; and
  3. the physiology of the eye.


1) Light


Light is electromagnetic radiation emitted by a light source with a wavelength of between 380 and 780 nanometers; it occupies the portion of the electromagnetic spectrum between the infrared and the ultraviolet. The light that we perceive as white is in reality a blend of different wavelengths in this interval of visible light, from violet to red. Proof of this is provided by the fact that when light passes through a transparent prism, it is refracted into a spectrum of color; we also see this when light passes through drops of water suspended in the atmosphere, where it is refracted into a rainbow.


In order to understand the printing process, there are two important characteristics of light to bear in mind:


  1. the color temperature; and
  2. the color rendering index.

a) Colour temperature


The color temperature of a light source is the numerical measure of its chromatic appearance, or hue. It is based on the principle that any object, if heated to a sufficiently high temperature, gives off light. The color of that light varies in a predictable manner with the increase in temperature: the object passes gradually from red to orange to yellow and then white and finally to bluish white. Thus the color temperature is the temperature, expressed in degrees kelvin (K), at which the color of the object exactly matches that of the light source.


b) Colour rendering index


The color rendering index (CRI or Ra) provides indications about how a particular light source renders the colors of the objects illuminated. It is a system derived from experiments carried out on vision to assess the impact of different light sources on the perceived color of objects and surfaces.

2) The physical properties of the material


The characteristics of the material are a decisive factor in how color is perceived. In fact, objects illuminated by light react in different ways according to their substance: an object that absorbs all the wavelengths of visible light appears black; if, on the contrary, it absorbs none of them, it appears white; if it is selective in the wavelengths it absorbs, it appears in one of the millions of colors that we find in nature.


3) The physiology of the eye


The eye, the principal sense organ of our visual system, receives information from the external environment through light. The crystalline lens focuses the light and the retina detects it by means of a layer of receptors, called cones and rods, which is connected to the brain by the optic nerve. The rods are used for vision in low-light conditions but are not particularly sensitive to color; cones, on the other hand, come in three types, which are each sensitive to different wavelengths (red, green, and blue), and determine with a certain precision the perception of the hue.
Despite this ability to distinguish variation in tone, the perception of color remains a subjective matter, dependent on the viewer’s concentration, habits, environmental conditions, and more.

A color can be determined in two ways: by varying the light (additive synthesis) or by varying the characteristics of the material (subtractive synthesis).


Three light sources, each of a single and specific wavelength that correspond to red, blue, or green light, can be combined in different combinations and quantities (i.e., intensity) in such a way as to obtain different shades of color, visible to the eye when a white material is illuminated with this beam. It is the principle on which digital video and still cameras operate, called additive synthesis.


If instead we use white light (i.e., light covering the whole spectrum of visible wavelengths), and tint the white material with three colors (blue, yellow, and red) in different quantities, the result is also a range of colors, but it has been created by partially absorbing, or subtracting, the white light. This is the principle on which printing, painting, and photographic film and film stock are based, called subtractive synthesis.

If we estimate the number of colors in existence to be 7.5 million, an empirical calculation leads to the following considerations:


  • humans are capable of distinguishing around a third of this number (2.5 million)
  • technologies based on additive synthesis reproduce around a quarter (1.8 million)
  • technologies based on subtractive synthesis reproduce 1.3 million at the most
  • the standard offset system does not exceed 400 thousand colours

It is clear that the photographic technique, although far from being able to reproduce all the variations in hue that exist, is not far from what the human eye is able to perceive. A standard print on paper, by contrast, has considerable limitations, as it is not even able to reproduce a third of the colors that may be present in a fresco or a painting or a fifth of those possible in a photograph.

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