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Gray Card
A gray card is a middle gray reference, typically used together with a reflective light meter, as a way to produce consistent image exposure and/or color in video production, film, and photography. A gray card is a flat object of a neutral-gray color that derives from a flat reflectance spectrum. A typical example is the Kodak R-27 set, which contains one card and one card, each with an 18% reflectance across the visible spectrum, and a white reverse side with a 90% reflectance. Note that flat spectral reflectance is a stronger condition than simply appearing neutral; this flatness ensures that the card always has the same color as its illuminant (see metamerism). Application Gray cards are used in a variety of ways by photographers, cinematographers, video engineers and video camera operators. Photography A primary use of gray cards is to provide a standard reference object for exposure determination in photography. A gray card is an (approximate) realization of a La ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visible Spectrum
The visible spectrum is the spectral band, band of the electromagnetic spectrum that is visual perception, visible to the human eye. Electromagnetic radiation in this range of wavelengths is called ''visible light'' (or simply light). The optical spectrum is sometimes considered to be the same as the visible spectrum, but some authors define the term more broadly, to include the ultraviolet and infrared parts of the electromagnetic spectrum as well, known collectively as ''optical radiation''. A typical human eye will respond to wavelengths from about 380 to about 750 nanometers. In terms of frequency, this corresponds to a band in the vicinity of 400–790 Terahertz (unit), terahertz. These boundaries are not sharply defined and may vary per individual. Under optimal conditions, these limits of human perception can extend to 310 nm (ultraviolet) and 1100 nm (near infrared). The spectrum does not contain all the colors that the human visual system can distinguish. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photography Equipment
Photography is the visual arts, art, application, and practice of creating images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is employed in many fields of science, manufacturing (e.g., photolithography), and business, as well as its more direct uses for art, film and video production, recreational purposes, hobby, and mass communication. A person who operates a camera to capture or take Photograph, photographs is called a photographer, while the captured image, also known as a photograph, is the result produced by the camera. Typically, a lens is used to focus (optics), focus the light reflected or emitted from objects into a real image on the light-sensitive surface inside a camera during a timed Exposure (photography), exposure. With an electronic image sensor, this produces an Charge-coupled device, electrical charge at each pixel, which is Image processing, electro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Color Chart
A color chart or color reference card is a flat, physical object that has many different color samples present. They can be available as a single-page chart, or in the form of swatchbooks or color-matching fans. Typically there are two different types of color charts: * Color reference charts are intended for color comparisons and measurements. Typical tasks for such charts are checking the color reproduction of an imaging system, aiding in color management or visually determining the hue of color. Examples are the IT8 and ColorChecker charts. * Color selection charts present a palette of available colors to aid the selection of spot colors, process colors, paints, pens, crayons, and so on – usually the colors are from a manufacturers product range. Examples are the Pantone and RAL colour standard, RAL systems. Color reference charts Color reference charts are used for color comparisons and measurements such as checking the color reproduction of an imaging system, and cali ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Camera
A digital camera, also called a digicam, is a camera that captures photographs in Digital data storage, digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film or film stock. Digital cameras are now widely incorporated into mobile devices like smartphones with the same or more capabilities and features of dedicated cameras. High-end, high-definition dedicated cameras are still commonly used by professionals and those who desire to take higher-quality photographs. Digital and digital movie cameras share an optical system, typically using a Camera lens, lens with a variable Diaphragm (optics), diaphragm to focus light onto an image pickup device. The diaphragm and Shutter (photography), shutter admit a controlled amount of light to the image, just as with film, but the image pickup device is electronic rather than chemical. However, unlike film cameras, digital cameras can display images on a screen immediately afte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Color Balance
In photography and image processing, color balance is the global adjustment of the intensities of the colors (typically red, green, and blue primary colors). An important goal of this adjustment is to render specific colors – particularly neutral colors like white or grey – correctly. Hence, the general method is sometimes called gray balance, neutral balance, or white balance. Color balance changes the overall mixture of colors in an image and is used for color correction. Generalized versions of color balance are used to correct colors other than neutrals or to deliberately change them for effect. White balance is one of the most common kinds of balancing, and is when colors are adjusted to make a white object (such as a piece of paper or a wall) appear white and not a shade of any other colour. Image data acquired by sensors – either photographic film, film or electronic image sensors – must be transformed from the acquired values to new values that are appropriate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lambertian Reflectance
Lambertian reflectance is the property that defines an ideal "matte" or diffusely reflecting surface. The apparent brightness of a Lambertian surface to an observer is the same regardless of the observer's angle of view. More precisely, the reflected radiant intensity obeys Lambert's cosine law, which makes the reflected radiance the same in all directions. Lambertian reflectance is named after Johann Heinrich Lambert, who introduced the concept of perfect diffusion in his 1760 book '' Photometria''. Examples Unfinished wood exhibits roughly Lambertian reflectance, but wood finished with a glossy coat of polyurethane does not, since the glossy coating creates specular highlights. Though not all rough surfaces are Lambertian, this is often a good approximation, and is frequently used when the characteristics of the surface are unknown. Spectralon is a material which is designed to exhibit an almost perfect Lambertian reflectance. Use in computer graphics In computer graph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metamerism (color)
In colorimetry, metamerism is a perceived matching of colors with different (nonmatching) spectral power distributions. Colors that match this way are called metamers. A spectral power distribution describes the proportion of total light given off (emitted, transmitted, or reflected) by a color sample at each visible wavelength; it defines the complete information about the light coming from the sample. However, the human eye contains only three color receptors (three types of cone cells), which means that all colors are reduced to three sensory quantities, called the tristimulus values. Metamerism occurs because each type of cone responds to the cumulative energy from a broad range of wavelengths, so that different combinations of light across all wavelengths can produce an equivalent receptor response and the same tristimulus values or color sensation. In color science, the set of sensory spectral sensitivity curves is numerically represented by color matching functions. Sou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Obverse And Reverse
The obverse and reverse are the two flat faces of coins and some other two-sided objects, including paper money, flags, seals, medals, drawings, old master prints and other works of art, and printed fabrics. In this usage, ''obverse'' means the front face of the object and ''reverse'' means the back face. The obverse of a coin is commonly called ''heads'', because it often depicts the head of a prominent person, and the reverse ''tails''. In numismatics, the abbreviation ''obv.'' is used for ''obverse'',David Sear. ''Greek Imperial Coins and Their Values.'' Spink Books, 1982. p. xxxv. while , )(Jonathan Edwards. ''Catalogue of the Greek and Roman Coins in the Numismatic Collection of Yale College, Volume 2.'' Tuttle, Morehouse & Taylor, 1880. p. 228. and ''rev.''Allen G. Berman. ''Warman's Coins And Paper Money: Identification and Price Guide.'' Penguin, 2008. are used for ''reverse''. Vexillologists use the symbols "normal" for the obverse and "reverse" for the reverse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflectance
The reflectance of the surface of a material is its effectiveness in reflecting radiant energy. It is the fraction of incident electromagnetic power that is reflected at the boundary. Reflectance is a component of the response of the electronic structure of the material to the electromagnetic field of light, and is in general a function of the frequency, or wavelength, of the light, its polarization, and the angle of incidence. The dependence of reflectance on the wavelength is called a ''reflectance spectrum'' or ''spectral reflectance curve''. Mathematical definitions Hemispherical reflectance The ''hemispherical reflectance'' of a surface, denoted , is defined as R = \frac, where is the radiant flux ''reflected'' by that surface and is the radiant flux ''received'' by that surface. Spectral hemispherical reflectance The ''spectral hemispherical reflectance in frequency'' and ''spectral hemispherical reflectance in wavelength'' of a surface, denoted and respectively, are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photography
Photography is the visual arts, art, application, and practice of creating images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is employed in many fields of science, manufacturing (e.g., photolithography), and business, as well as its more direct uses for art, film and video production, recreational purposes, hobby, and mass communication. A person who operates a camera to capture or take Photograph, photographs is called a photographer, while the captured image, also known as a photograph, is the result produced by the camera. Typically, a lens is used to focus (optics), focus the light reflected or emitted from objects into a real image on the light-sensitive surface inside a camera during a timed Exposure (photography), exposure. With an electronic image sensor, this produces an Charge-coupled device, electrical charge at each pixel, which is Image processing, electro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
