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Giclée & Digital Printing GlossaryOur Glossary is broken up into two sections:Giclée
Computer/Digital Terminology Additive Primaries Red, Green, and Blue (RGB) light that is used in additive color models. When added together in proper proportion, these three colors of light produce white. Artifact A visible defect in an image caused by limitations in the software or hardware; a blemish. Bitmap An image comprised of small squares arranged in a grid. Each square is a pixel. The number of pixels per inch defines the resolution of the bitmap. BMP (or .bmp) A bitmap graphics file format established by Microsoft and native to the Windows OS. Channel In the manipulation of a Digital Image File, refers to a single-color image that can be edited separately from the other color channels comprising a color space - for example the Red channel of an RGB image. CMYK A Subtractive color model that uses cyan, magenta, yellow and black in color printing; a color model used in the printing of colors in "four-color" printing. A number of variations of this model are used in giclée printing. Color Management System (CMS) A system used to match color across a variety of different input, display, manipulation, and output devices. Color Separation The process of separating an image into the four (or more) color components used for printing - commonly cyan, magenta, yellow and black. In giclée printing, there is often a greater degree of separation; i.e. six-color separation. The same term also refers to the four sheets of film that result from the process of separating a color image which are used to etch printing plates for four-color offset printing. Color Space A model for representing color in terms of measurable values, such as the amount each of red, green, and blue in an additive color image. RGB and CMYK "color spaces" correspond to color devices - monitors and printers - respectively. See Gamut Colorant An ink, dye, toner, paint, or substance which modifies
the color of the substrate to which it is applied. Composite Printer Any output device that can print color directly without first creating physical color separations. A giclée print is a composite color print. Continuous Tone Image Describes a photographic or fine art image that contains a series of unbroken gradient tones from black to white such as a transparency, photograph, or painting. Continuous tones cannot be reproduced as such using any type of non-photographic printing process but must first be screened to translate the image into a collection of dots. The smaller the dots and the more closely they are spaced, the better the reproductive quality of the image. Giclée prints are usually produced at a resolution of 600+ dots per inch. Custom Color System A system of named (or numbered) colors that can be matched by a printing device using process (such as a giclée printer) or spot (such as an offset press) colors. Pantone is the most widely used custom color system in the United States. Depth Properly termed Bit Depth, this is the amount of information necessary to define each pixel in a raster image. B & W images need only one bit per pixel. 256 shade grayscale images require 8 bits (1 byte) per pixel. Photographic quality color images require 24 bits per pixel for RGB images & 32 bits per pixel for CMYK images. Digital Image File This is a computer file, usually saved in TIFF, PSD, or JPEG formats at a minimum of 300dpi, which contains the image to be printed. A Digital Image File's size depends on the size of the image to be printed. A 4" x 5" image, at actual size, is about 10Mb. An 8" x 10" file is usually about 40Mb. Electroptical (e-lek-trop-ti-kal ) An interconnected Electronic and Optical device structure. Four-color Printer A printing device that uses cyan, magenta, yellow and black ink or toner. Four-Color Process A printing process which uses cyan, magenta, yellow and black inks to reproduce most of the visible colors of the spectrum. See Six-Color Process Gamma A numeric value representing the relationship (gamma curve) between the input and output values of a color device. If gamma equals 1, input values are mapped exactly to output values. Gamut A range of colors. A device gamut is the range of colors that a device, such as a printer, can produce. An image gamut is the range of colors in a particular image. In many cases with fine art giclée, the image gamut exceeds the printer gamut and requires careful, highly specialized manipulation by the giclée printing artist. Giclée Printing Artist A composite-printing smart computer pro with extensive knowledge of the manipulation of color in fine art reproduction. Halftoning A method for representing an original continuous tone image using a pattern of dots, lines, or other repeating patterns. ICC Profile An industry standard color profile format developed by the International Color Consortium (ICC) that describes the color capabilities, including the gamut of a color device based on the differences between an ideal and the current device. ICC profiles are managed on Mac OS computers in "ColorSync" and on Windows OS computers in Image Color Matching (ICM). A giclée printing artist should use equipment which supports ICC profiles. JPEG (or .jpg) A graphics file format defined by the Joint
Photographic Experts Group committee of the International Standards Organization
(ISO); a standard for digital compression of still image graphic data.
"JPEG" files are able to be saved in a variety of resolution
qualities. Only the best are suitable for giclée. Metamerism A phenomenon in which two colors composed of different combinations of light wavelengths appear identical under a specific lightsource, but may look different under other light sources. Moiré An undesirable pattern in printed graphic images deriving from errors in halftone angles, frequency, and alignment. It takes a great deal of experience on the part of the giclée printing artist not only to recognize where the fault lies, but also to implement an appropriate corrective measure. Offset Lithography A printing process in which ink from a tray is transferred to a printing plate; thence to a rubber roller, and finally to the paper. The operative principle is that ink and water do not mix. The metal plate has been etched to water-repellency with the image's halftone. Therefore, when the plate is wetted and then passes the ink tray, ink adheres only to the dry (imaged) areas. Pixel The smallest element of a raster image. The term is a combination of the words "picture" and "element". PostScript A device-independent page description language developed by Adobe which is used by computers to communicate with printers to print pictures and text. Process Colors The four ink colors used in printing to simulate full spectrum color images: Cyan, Magenta, Yellow, and blacK. Raster Image Electronic representation of printable data using a grid of points called pixels. Resolution The number of pixels per inch (ppi) in a bitmap image or the number of dots per inch (dpi) that a device can render. The minimum standard for fine art giclée printing is 600+ dpi. RGB An additive color model that makes a range of colors by combining red, green, and blue light, called the additive color primaries. Commonly used to refer to the color space, mixing system, and computer monitor in color computer graphics. RIP Rasterized Image Processor (specialized computer) used to drive a more complex printer. Separation(s) See Color Separation Six-Color Process A printing process which uses light cyan, cyan, light magenta, magenta, yellow and black inks to reproduce most of the visible colors of the spectrum. The six color process is capable of more accurate reproduction than the four-color process and is more commonly used in giclée printing. See Four-Color Process Subtractive Color Model A system in which color is produced by combining colorants such as paints, inks, or dyes on a substrate such as paper, vinyl, canvas, or acetate. All printing devices use the subtractive color model. It is termed subtractive because the colorant(s) used absorbs (subtracts) all colors except the one desired from the light striking the substrate. Hence the human eye sees only the remaining light which is that of the desired color. See Additive Color Model. Subtractive Primaries Cyan, Magenta and Yellow colorants used in subtractive color systems for color printing. Combining these primaries produces darker colors. Black is added to the subtractive primaries to compensate for deficiencies of the inks, and for more efficient black printing. Substrate The material onto which printing is done. TIFF (or .tif) Tagged Image File Format. This graphics file
format is one of the most frequently used for transferring digital images among
various graphics applications. Acid Free (Neutral pH)Papers without acid in the pulp and a pH of 7.0 or more. Basis Weight The basis weight is the weight of a ream (500 sheets) of paper in a given size. Different types of paper (i.e. Cover, Text, Writing) have different Basic Sizes depending on the most common historical size in which they were manufactured. For example, Cover stock is measured in 20" x 26" sheets. Therefore, 500 sheets of 100# (100 pound) cover sheets measuring 20" x 26" would weigh 100 pounds. Writing Paper basic size is 17" x 22", Newsprint Paper Basic Size is 24" x 36", etc. Board A thicker paper made by plying together multiple layers of paper. Usually with opposing grains, the combination of paper and adhesive substance usually produces quite a hard-to-bend result. The minimum thickness for a "board" is generally accepted to be .06". Buffered Papers which have had the acid neutralized, usually by the addition of salcium carbonate, to enhance their longevity Caliper This is the usual measurement of paper thickness commonly expressed in thousandths of an inch (mils). One point or one mil equals one thoudandth of an inch. A 30 point paper will measure .030" thick. See also Basis Weight Canvas Not really a paper, canvas (usually made of cotton) is a commonly used giclée printing substrate. Coated Papers which have had none or more of a wide range of additives such as clay, rosin, and plastic, rolled into their surfaces under extreme pressure. There are many reasons for this including gloss surfacing, making the paper more receptive to various post-manufacture additives such as paints, inks, and dyes, or enhancing the water-resistive quality of the sheet. Cold Pressed A paper, the surface of which is somewhat textured. The texture is produced by rolling the finished sheet between cold cylinders. See Hot Pressed Deckle Edge The feathered edge of an uncut new paper which is the result of the wet pulp running over the edge of the paper mould during manufacture. Deckle is sometimes imitated by tearing the sheet along a straightedge while it is still wet, or by watercutting the edge. Dye A dye is a colored soluable substance, used to make certain inks and dyes, which imparts its color to another material by staining the other material or substrate. Important: Dyes make Solutions See Pigment Grain This is the direction of the majority of the fibers which
make up the paper. It is determined by the direction of flow of the pulp mixture
during manufacture. The importance of the Grain is relative to folding. Paper
folds more easily "with" the grain; in other words, parallel to the
pulp flow direction and not in the direction which would cause you to be folding
the fibers. Gram Weight In addition to basis weight, another common measurement of paper is in Grams per Square Meter (G.S.M.) This is the best comparitive measure as it does not vary by sheet size. Handmade Paper Exactly as the term implies, a frame (similar to a canvas stretcher frame) is stretched with a wire screen. This device is referred to as a mould. The mould is then filled with wet pulp and shaken to distribute fibers and remove liquid. The resultant wet mat is then dried, rolled, pressed, or any of a number of other processes, and then allowed to dry. Voilá: a Sheet of paper! No two sheets of handmade paper are ever exactly the same. See Machinemade Laid Paper which features regularly spaced lines, usually about one inch apart, running parallel to the grain. These are sometimes referred to as Chain Lines. Linen Paper which has a surface resembling the cross-hatched appearance of linen. Long ago this was produced by drying between sheets of linen cloth but is now accomplished by rolling between metal rollers etched with a linen weave. Hot Pressed A paper, the surface of which is smooth. The smoothness is produced by rolling the finished sheet between hot cylinders. See Cold Pressed Machinemade Paper The papermaking machine is called a fourdriner. In contrast to handmade, it is capable of producing very consistent qualities in both sheet and roll paper. See Handmade Paper Opacity The quality of a paper which prevents "show-through". This is inconsequential to an artist as work is normally done on one side of a sheet. However, when books are part of the equation, this becomes increasingly important. pH This measure of the alkalinity or acidity of any fine art
substrate is exceedingly important. pH is measured on a scale of 0 to 14. From 0
to 7 is acid; 7.0=neutral; 7 to 14 is alkaline. Acidic substrates, be they
paper, canvas, wood or other, will eventually not only degrade but will also
impart acid to the coloring medium (paint, watercolor, etc), causing it to
degrade as well. The closer to neutral (but at least pH 7.0) the better for fine
art. Pigment A very finely powdered coloring substance used to make paints and certain inks which is insoluble in the liquid vehicle being used as a transfer medium. Pigment transfers its color by being spread across the surface of the receiving substrate. Important: Pigments make Mixtures. See Dye Rice Paper There is no such thing. This is a misnomer commonly used to describe Oriental papers, probably derived from the use of rice starch to size papers of mulberry pulp. Size The additive, sometimes rosin or starch, applied to either finished paper or liquid pulp, to control various actions of subsequent applications of liquids or coloring materials. Translucency The ability to permit the passage of light without being transparent. Vellum A term usually used to designate translucent drawing or drafting papers which are usually both strong and finely textured. Watercolor Paper (W/C) A generic term for the preferred giclée printing substrate. Usually a heavier and slightly off-white mould-made sheet, the papers are commonly used in giclée printing are Arches and Rives BFK as well as for watercolor painting. Watermark Traditionally formed by sewing a maker's mark into the mould's wire screen and thusly imparting it to the finished paper, watermarks today are produced in many ways. They can be done by etching a design onto one of the rollers used in the manufacturing process or by altering the ink coverage when making a print. Wove Papers which show no textural or manufacturing lines when
held up to a light source; in other words, paper which is uniformly consistent
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