Grayscale. Brightness. Tints and shades. In common language, the term "shade" can be generalized to furthermore encompass any varieties of a particular color, whether technically they are shades, tints, tones, or slightly different hues;[2] while the term "tint" can be generalized to refer to the any lighter or darker variation of a color (e.g. Tinted windows).[3] When mixing colored light (additive color models), the achromatic mixture of spectrally balanced red, green and blue (RGB) is always white, not gray or black.
When we mix colorants, such as the pigments in paint mixtures, a color is produced which is always darker and lower in chroma, or saturation, than the parent colors. This moves the mixed color toward a neutral color—a gray or near-black. Lights are made brighter or dimmer by adjusting their brightness, or energy level; in painting, lightness is adjusted through mixture with white, black or a color's complement. An extension of the color wheel: the color sphere. References[edit] See also[edit] Lightness. Three hues in the Munsell color model. Each color differs in value from top to bottom in equal perception steps. The right column undergoes a dramatic change in perceived color. In colorimetry and color theory, lightness, also known as value or tone, is a representation of variation in the perception of a color or color space's brightness.
It is one of the color appearance parameters of any color appearance model. Various color models have an explicit term for this property. The Munsell color model uses the term value, while the HSL color model and Lab color space use the term lightness. In subtractive color (i.e. paints) value changes can be achieved by adding black or white to the color. Relationship between lightness, value, and luminance[edit] Observe that the lightness is 50% for a luminance of around 18% relative to the reference white. Priest et al. provide a basic estimate of the Munsell value (with Y running from 0 to 1 in this case):[4] Wyszecki simplifies this to:[14] where .
Color. Color (American English) or colour (British English; see spelling differences) is the visual perceptual property corresponding in humans to the categories called red, blue, yellow, and others. Color derives from the spectrum of light (distribution of light power versus wavelength) interacting in the eye with the spectral sensitivities of the light receptors.
Color categories and physical specifications of color are also associated with objects or materials based on their physical properties such as light absorption, reflection, or emission spectra. By defining a color space, colors can be identified numerically by their coordinates. Because perception of color stems from the varying spectral sensitivity of different types of cone cells in the retina to different parts of the spectrum, colors may be defined and quantified by the degree to which they stimulate these cells. The science of color is sometimes called chromatics, colorimetry, or simply color science. Physics of color Perception. Optics. Optics is the branch of physics which involves the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it.[1] Optics usually describes the behaviour of visible, ultraviolet, and infrared light.
Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties.[1] Some phenomena depend on the fact that light has both wave-like and particle-like properties. Explanation of these effects requires quantum mechanics. When considering light's particle-like properties, the light is modelled as a collection of particles called "photons".
Quantum optics deals with the application of quantum mechanics to optical systems. Optical science is relevant to and studied in many related disciplines including astronomy, various engineering fields, photography, and medicine (particularly ophthalmology and optometry). History[edit] . Where and . Light. A triangular prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (blue) get separated Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to visible light, which is visible to the human eye and is responsible for the sense of sight.[1] Visible light is usually defined as having a wavelength in the range of 400 nanometres (nm), or 400×10−9 m, to 700 nanometres – between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths).[2][3] Often, infrared and ultraviolet are also called light.
The main source of light on Earth is the Sun. Sunlight provides the energy that green plants use to create sugars mostly in the form of starches, which release energy into the living things that digest them. Electromagnetic spectrum and visible light The behaviour of EMR depends on its wavelength. Speed of light Main article: Speed of light Optics Refraction where Table 1. Óptica geométrica.
Formación de un arco iris por medio de la óptica geométrica. La óptica geométrica usa la noción de rayo luminoso; es una aproximación del comportamiento que corresponde a las ondas electromagnéticas (la luz) cuando los objetos involucrados son de tamaño mucho mayor que la longitud de onda usada; ello permite despreciar los efectos derivados de la difracción, comportamiento ligado a la naturaleza ondulatoria de la luz. Esta aproximación es llamada de la Eikonal y permite derivar la óptica geométrica a partir de algunas de las ecuaciones de Maxwell.
Propagación de la luz[editar] Reflexión y refracción[editar] El fenómeno más sencillo de esta teoría es la de la reflexión, si pensamos unos minutos en los rayos luminosos que chocan mecánicamente contra una superficie que puede reflejarse. La segunda ley de la reflexión nos indica que el rayo incidente, el rayo reflejado y la normal con respecto a la superficie reflejada están en el mismo plano.[2] Ley de Snell[editar] Lentes[editar] Espejos[editar] Luz. Se llama luz (del latín lux, lucis) a la parte de la radiación electromagnética que puede ser percibida por el ojo humano. En física, el término luz se usa en un sentido más amplio e incluye todo el campo de la radiación conocido como espectro electromagnético, mientras que la expresión luz visible señala específicamente la radiación en el espectro visible. La óptica es la rama de la física que estudia el comportamiento de la luz, sus características y sus manifestaciones.
El estudio de la luz revela una serie de características y efectos al interactuar con la materia, que permiten desarrollar algunas teorías sobre su naturaleza. En el 55 A.C., Lucrecio, un poeta romano atomista, escribió: "La luz y calor del sol; Estas están compuestas de átomos diminutos que, cuando se metieron, no pierden ningún tiempo en el tiroteo intermedio del aire en la dirección impartida por el empujón. –" De rerum natura Velocidad finita[editar] Refracción[editar] Ejemplo de la refracción.
Interferencia[editar] Cámara oscura. La cámara oscura es un instrumento óptico que permite obtener una proyección plana de una imagen externa sobre la zona interior de su superficie. Constituyó uno de los dispositivos ancestrales que condujeron al desarrollo de la fotografía. Los aparatos fotográficos actuales heredaron la palabra cámara de las antiguas cámaras oscuras. Consiste en una caja cerrada y un pequeño agujero por el que entra una mínima cantidad de luz que proyecta en la pared opuesta la imagen del exterior. Si se dota con papel fotográfico se convierte en una cámara fotográfica estenopeica. Esquema de una cámara oscura del siglo XVIII.
Originalmente, consistía en una sala cerrada cuya única fuente de luz era un pequeño orificio practicado en uno de los muros, por donde entraban los rayos luminosos reflejando los objetos del exterior en una de sus paredes. El orificio funciona como una lente convergente y proyecta, en la pared opuesta, la imagen del exterior invertida tanto vertical como horizontalmente. Paper size. A size chart illustrating the ISO A series and a comparison with American letter and legal formats.
Comparison of some paper and photographic paper sizes close to the A4 size. Paper sizes affect writing paper, stationery, cards, and some printed documents. The international standard for envelopes is the C series of ISO 269. International paper sizes[edit] The following international paper sizes are included in Cascading Style Sheets (CSS): A3, A4, A5, B4, B5.[2] A series[edit] A size chart illustrating the ISO A series.
The base A0 size of paper is defined as having an area of 1 m2 and a dimension ratio of 1 to √2, making the A0 paper size exactly m × m. Successive paper sizes in the series A1, A2, A3, and so forth, are defined by halving the preceding paper size across the larger dimension. The behavior of the aspect ratio is easily proven: on a sheet of paper, let a be the long side and b be the short side; thus, a/b = √2. The DIN 476 standard spread quickly to other countries. B series[edit] Canons of page construction. The canons of page construction are a set of principles in the field of book design used to describe the ways that page proportions, margins and type areas (print spaces) of books are constructed.
The notion of canons, or laws of form, of book page construction was popularized by Jan Tschichold in the mid to late twentieth century, based on the work of J. A. van de Graaf, Raúl M. Rosarivo, Hans Kayser, and others.[1] Tschichold wrote, “Though largely forgotten today, methods and rules upon which it is impossible to improve have been developed for centuries. To produce perfect books these rules have to be brought to life and applied.”[2] Kayser's 1946 Ein harmonikaler Teilungskanon[3] had earlier used the term canon in this context. Typographers and book designers apply these principles to this day, with variations related to the availability of standardized paper sizes, and the diverse types of commercially printed books.[4] Van de Graaf canon[edit] Golden canon[edit] See also[edit] [edit]
Category:Digital typography. From Wikipedia, the free encyclopedia This category contains articles on computer-related typography topics. The main article for this category is Digital typography. Subcategories This category has the following 8 subcategories, out of 8 total. Pages in category "Digital typography" The following 58 pages are in this category, out of 58 total. Category:Page layout. Letterpress printing. This article is about the art and technique of relief printing with a printing press. For a historical account of its origins and societal impact, see printing press. The general form of letterpress printing with a platen press, showing the relationship between the form (the type), the pressure, the ink, and the paper A printer inspecting a large form of type on a cylinder press. Each of the islands of text represents a single page, the darker blocks are images.
Letterpress printing is a technique of relief printing using a printing press, a process by which many copies are produced by repeated direct impression of an inked, raised surface against sheets or a continuous roll of paper.[1] A worker composes and locks movable type into the "bed" or "chase" of a press, inks it, and presses paper against it to transfer the ink from the type which creates an impression on the paper. History[edit] Printer operating a Gutenberg-style screw press Industrialization[edit] North American history[edit]