In printing, under color removal (UCR) is a process of eliminating overlapping yellow, magenta, and cyan that would have added to a dark neutral (black) and leaving the black ink only, called a full black, during the color separation process. Under color removal is used in process color printing. Black ink used to add details and darkness in shadowed areas is called a skeletal black.
With current[as of?] ink technology, the total CMYK ink in the shadows refuses to stick after it reaches the dark shadows (usually above a 250% total CMYK coverage), and begins to peel off. To prevent this, printers developed UCR, in which neutral shadows–which would have normally been produced by overprinting the four inks cyan, magenta, yellow and black on top of each other (high ink coverage)–are replaced with the single layer of black. UCR removes the color inks under the black, resulting in a single layer of ink which sticks to the sheet better, and saves on the consumption of ink.
There is no universal rule for UCR. The amount required will depend on the printing press, paper, and ink in use. Advantages are that it solves the ink-not-sticking problem and that using black ink is less expensive than using several colors. A disadvantage is that black ink by itself in a shadow may not be dark enough. In this case CMY colors may be added for more accurate reproduction, this process being under color addition (UCA).
UCR is generally not recommended for use in printing due to its tendency to produce dull-looking images and artwork. (This problem can often be obviated on coated paper by use of an aqueous coating or UV coating applied on the press or as post-press. A press-applied coating can also eliminate the ink-sticking problem.) The main exception to this rule is that where working in newsprint, UCR is the best way to avoid the associated ink limit and registration issues. UCR is also recommended for some specific paper stocks, depending on the coloration and texture of the paper.
Cyan is the color between blue and green on the visible spectrum of light. It is evoked by light with a predominant wavelength between 500 and 520 nm, between the wavelengths of green and blue.
The CMYK color model is a subtractive color model, based on the CMY color model, used in color printing, and is also used to describe the printing process itself. The abbreviation CMYK refers to the four ink plates used: cyan, magenta, yellow, and key.
Magenta is a purplish-red color. On color wheels of the RGB (additive) and CMY (subtractive) color models, it is located precisely midway between blue and red. It is one of the four colors of ink used in color printing by an inkjet printer, along with yellow, cyan, and black to make all the other colors. The tone of magenta used in printing, printer's magenta, is redder than the magenta of the RGB (additive) model, the former being closer to rose.
Pantone LLC is an American limited liability company headquartered in Carlstadt, New Jersey, and best known for its Pantone Matching System (PMS), a proprietary color order system used in a variety of industries, notably graphic design, fashion design, product design, printing, and manufacturing and supporting the management of color from design to production, in physical and digital formats, among coated and uncoated materials, cotton, polyester, nylon and plastics.
Color photography is photography that uses media capable of capturing and reproducing colors. By contrast, black-and-white or gray-monochrome photography records only a single channel of luminance (brightness) and uses media capable only of showing shades of gray.
Color theory, or more specifically traditional color theory, is the historical body of knowledge describing the behavior of colors, namely in color mixing, color contrast effects, color harmony, color schemes and color symbolism. Modern color theory is generally referred to as Color science. While there is no clear distinction in scope, traditional color theory tends to be more subjective and have artistic applications, while color science tends to be more objective and have functional applications, such as in chemistry, astronomy or color reproduction. Color theory dates back at least as far as Aristotle's treatise On Colors. A formalization of "color theory" began in the 18th century, initially within a partisan controversy over Isaac Newton's theory of color and the nature of primary colors. By the end of the 19th century, a schism had formed between traditional color theory and color science.
Subtractive color or subtractive color mixing predicts the spectral power distribution of light after it passes through successive layers of partially absorbing media. This idealized model is the essential principle of how dyes and pigments are used in color printing and photography, where the perception of color is elicited after white light passes through microscopic "stacks" of partially absorbing media allowing some wavelengths of light to reach the eye and not others, and also in painting, whether the colors are mixed or applied in successive layers.
In offset printing, a spot color or solid color is any color generated by an ink that is printed using a single run, whereas a process color is produced by printing a series of dots of different colors.
RYB is a subtractive color model used in art and applied design in which red, yellow, and blue pigments are considered primary colors. Under traditional color theory, this set of primary colors was advocated by Moses Harris, Michel Eugène Chevreul, Johannes Itten and Josef Albers, and applied by countless artists and designers. The RYB color model underpinned the color curriculum of the Bauhaus, Ulm School of Design and numerous art and design schools that were influenced by the Bauhaus, including the IIT Institute of Design, Black Mountain College, Design Department Yale University, the Shillito Design School, Sydney, and Parsons School of Design, New York.
Color printing or colour printing is the reproduction of an image or text in color.
Within the CMY color space used in color printing, a range of colors can be achieved by combining the three primary colors. This combination can be thought of as a hue component and a grey component. If the grey component is replaced by black ink, the same color is being achieved by using two primaries and black. The substitution of black for the grey component is described as grey component replacement (GCR).
In printing, trap expresses the degree to which ink already printed on a substrate accepts another layer printed on top of it compared to how well the substrate accepts that ink.
Rich black, in printing, is an ink mixture of solid black over one or more of the other CMYK colors, resulting in a darker tone than black ink alone generates in a printing process.
In color science, a color model is an abstract mathematical model describing the way colors can be represented as tuples of numbers, typically as three or four values or color components. When this model is associated with a precise description of how the components are to be interpreted, taking account of visual perception, the resulting set of colors is called "color space."
Gum printing is a way of making photographic reproductions without the use of silver halides. The process uses salts of dichromate in common with a number of other related processes such as sun printing.
CcMmYK, sometimes referred to as CMYKLcLm or CMYKcm, is a six-color printing process used in some inkjet printers optimized for photo printing. It complements the more common four-color CMYK process, which uses only cyan, magenta, yellow and black, by adding light cyan and light magenta. Individually, light cyan is often abbreviated Lc or c, and light magenta Lm or m.
In color printing, print registration is the layering of printed patterns to form a multicolor pattern. Registration error is the "position misalignment in the overlapped patterns." Machine components such as the print cylinder, doctor blade assembly, printing plates, stress/friction and more, affect the registration of the machine. Inconsistencies among these components can cause the printing press to fall out of registration; that is when press operators will begin to see defects in their print. There are many different ways to achieve proper registration, many of which employ the alignment of registration marks. Many press manufacturers have installed automatic register systems to assist the operator in getting the print back into proper alignment.
Thermal paper is a special fine paper that is coated with a material formulated to change color locally when exposed to heat. It is used in thermal printers, particularly in inexpensive devices such as adding machines, cash registers, and credit card terminals and small, lightweight portable printers.
There are three types of color mixing models, depending on the relative brightness of the resultant mixture: additive, subtractive, and average. In these models, mixing black and white will yield white, black and gray, respectively. Physical mixing processes, e.g. mixing light beams or oil paints, will follow one or a hybrid of these 3 models. Each mixing model is associated with several color models, depending on the approximate primary colors used. The most common color models are optimized to human trichromatic color vision, therefore comprising three primary colors.
The color cyan, a greenish-blue, has notable tints and shades. It is one of the subtractive primary colors along with magenta, and yellow.
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