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Terminology
From gamut to giclée to gamma

We have included a glossary of terms on this website which we feel will be of benefit to whoever is involved in the giclée printing process. We find that our clients have a good grasp of the exacting standards that they need, and some essential vocabulary could be helpful. This glossary will hopefully help the process of producing giclée editions for our customers.
LIST OF TERMS: imaging
- addressable resolution
The maximum resolution of any device. The finite number of pixels that any imaging device is capable of creating, manipulating or imaging.
- aliasing
The visual stair-stepping of edges (jagged edges) that occurs in an image when the resolution is too low. Can be caused by improper image sampling or improper image processing. (see "jaggies")
- archiving
Retention of images, often on CD-ROM. Information necessary to reproduce the print is also archived, including ink, tables, sizes, and media used.
- artefact
In digital graphic applications, unwanted visual anomalies or defects generated by an input or output device, or by a software operation, that degrade image quality. (see also "aliasing" and "moiré pattern")
- banding
Patterns (stripes) on a print caused by insufficient colour or grey-scale ranges within the output device's image processor, or insufficient information contained within the original scan. Creates harsh, well-defined transitions between different ranges.
- bit depth
The maximum number of bits that are used to define a pixel. A measure of the defined brightness range. The colour depth or pixel values for a digital image. The number of possible colours or shades of grey that can be included in an image.
- bitmap
A rasterized graphic image formed by a rectangular grid of pixels or dots.
- capture
Acquiring information, such as an image, with a scanner or digital-camera device.
- CCD (charged coupled device)
Light-detection device used in many popular scanners, digital cameras, and video cameras that generates electrical current in direct proportion to how much light strikes areas of the sensor.
- channel
A component of a digital image that carries the data for a colour component or a mask.
- clipping
The grouping (usually unwanted) of all tones or colours above or below a certain value into one composite tone. The loss of visual information caused by too little contrast, in which certain grey scale values are lost or compressed either into the range of pure white or pure black.
- collage
Collage involves the creation of artworks that include elements that have previous existence as separate items. They may be found elements, transformed elements, or elements created entirely by the artist. Digital collages may be defined as digitally created artworks that involve the bringing together of separate images (which may or may not have existed in non-digital form and which may or may not have been created or altered by the artist) and digitally "pasting" them in place in order to create a new work. Digital collages may also contain digital drawing, digital painting, or other digital media.

In both montage and collage, multiple sources are used to create a single image. In montage, the disparity of the sources in invisible. In collage, the disparity of the sources is visible, sometimes so much so that the whole is fractured into separate elements contained within a single area.
- continuous tone
A photographic image containing gradient tones. For printing purposes, continuous-tone images are converted to dot patterns (halftones).
- crop
To remove part of an image.
- digital collage
The process of electronically simulating traditional collage techniques by pasting together disparate images into a cohesive visual whole, resulting in a new image.
- digital imaging
The process of image capture, manipulation and final image form, accomplished by digital systems.
- digitize
The process of converting analogue data to digital information.
- dithering
A graphics display or printing process that uses a combination of dots or textures to simulate an original image or an output device. The purpose is to create the impression of a continuous-tone grey-scale or colour image. (Diffuse dithering: method for printing continuous tone images on a laser printer, in which the greyscale information is represented by randomly located printer dots.)
- dots per inch (DPI)
(see "DPI")
- down-sampling
The process of receiving data from another computer, server or system. The reduction in resolution of an image, necessitating a loss in detail.
- effective resolution
The final appearance of a scan that has been enhanced to produce more data than the scanner can record. This is done by interpolation.
- Encapsulated Postscript File (EPS)
An Adobe graphic file format. EPS translates graphics and text into a code which the printer can read and print. EPS files hold both low-resolution "viewfiles" and high-resolution PostScript image descriptions. A vector-based, computer graphics file format developed by Adobe Systems. EPS is the preferred format for many computer illustrations because of its efficient use of memory and fine colour control.
- feathering
A technique in many image-editing programs that allows for the softening of the edge around a selection.
- filters
Software or subprograms within image manipulation software that employ algorithms to control modifications to digital images by altering the values or arrangement of entire or selected areas of an image.
- gamma
A mathematical curve representing both the contrast and brightness of an image. The steepness of the curve indicates greater contrast calculated as a trigonometric tangent function.
- halftone
The process of reproducing a continuous tone image as a series of various sized dots within a fixed grid that can be reproduced with ink. The finer the dot grid, the higher the quality of the reproduction.
- histogram
A graphical display that represents the distribution of tones within an image. The horizontal coordinate represents each pixel value possible from black to white. The vertical values indicate the number of pixels in the image that occur at each value level.
- interpolation
A technique for increasing the size of a graphic file by creating pixels. Also an extrapolation algorithm. There are two types, sequential and bi-cubic. Note: increasing the size of an image by interpolation does not increase or enhance the ability to resolve the detail in that image. It only makes the details that are already present larger.
- JPEG (Joint Photographic Experts Group)
Standardized image compression format developed by the Joint Photographic Experts Group. Usually used for compressing full-colour or grey-scale images.
- Kelvin
The name of the absolute temperature scale. Used in imaging to define the quality of a light source by referring to the absolute temperature of a black body that would radiate equivalent energy. Generally, a tungsten reading lamp is rated at 2800 degrees Kelvin, while TV or Film quartz lights are rated at 3200 degrees Kelvin, and outdoor light averages around 5600 degrees Kelvin. The higher the Kelvin temperature the more bluish the light appears.
- line art (or line drawing)
1. Single colour diagrams or drawings. 2. An image that requires sharp edges and high contrast between areas of the image that have ink and those areas that do not have ink. A drawing that consists only of black and white with no intermediate greyscale information. These images require a higher resolution to create the sharpness that is necessary.
- mask
A special effect that can modify images so that only part of the image can be seen, or so that the image blends into the background.
- moiré
An undesirable artefact or pattern that can appear in output film, or a created special effect. It appears as a regular pattern of "clumping" of colours. A moiré pattern is created by juxtapositions of two repetitive graphic structures. An often undesirable element in a digital scan, but a natural visual occurrence created when similar patterns are superimposed and a third pattern is inferred wherever the two similar patterns do not completely match.
- mottling
A texturing seen in the smooth or monotone areas of an image. This can be due to faulty processing and a number of improperly used digital processes, e.g., excessive unsharp masking.
- newton rings
Concentric multicoloured rings that occur when film is in contact with glass; a problem in scanning from negatives or transparencies.
- optical resolution
The maximum physical resolution of a device. Optical resolution provides better quality than interpolated resolution (of the same number), which uses software to create additional image information.
- PDF (Portable Document File)
A proprietary format developed by Adobe Systems for the transfer of designs across multiple computer platforms.
- pixel
Term derived from pi(x)cture element. Refers to the simplest or smallest element of a digital image.
- posterization
An effect created by having a limited number of levels or gradient steps within an image. This may be a planned/desired effect, or it may be a mistake requiring correction.
- resampling
Changing the resolution of a bitmap file without altering its physical size.
- scale
To enlarge or reduce an image by increasing or decreasing the number of scanned pixels or the sampling rate, relative to the number of samples per inch needed by the printer or other output device. (see also "interpolation")
- selection
Any of several processes by which the digital artist can isolate a portion of a digital image in order to perform additional work or protect the selected area from manipulations applied to the remaining "unprotected" areas. Similar to frisket paper and masking tape in traditional painting.
- service bureau
A company that typically offers custom print-output production services, which can include digital colour graphics.
- shadow point
The darkest tone printable in an image without being black. All tonal values below this threshold will print as black with no detail.
- spectrophotometer
Photometric device for the measurement of spectral transmittance, spectral reflectance, or relative spectral emittance. Spectrophotometers are normally equipped with dispersion optics (prism or grating) to give a continuous spectral curve. Commonly called "spectros."
- sRGB
One of several standard RGB colour working spaces. Best used for images on the Internet.
- subsampling
Scanning at a less-than-optimum sampling rate.
- thumbnail
A small low-resolution version of an image.
- TIFF (Tagged Image Format File)
A file format for storage of digital images.
- tiling
The process of breaking down an image or page into sections for editing or printing purposes.
- ultraviolet light (UV)
Radiant energy with wave lengths slightly shorter than the visible spectrum.
- unsharp mask
A sharpening process that first blurs the edges then subtracts the image from the blurred areas to yield an image of apparent enhanced sharpness.
- vector image
A computer image that uses mathematical descriptions of paths and fills to define the graphic, as opposed to individual pixels.
- white balance
The balancing of colour components to create pure white when photographing or scanning a white object. A substitute for a colour temperature setting.
 
Some terms here are taken from the Glossary of Digital Art and Printmaking, compiled by the Digital Art Practices & Terminology Task Force (DAPTTF).
Copyright © 2006, DAPTTF. See: www.dpandi.com/glossary.
 
ART4SITE
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Please browse the Glossary which has been divided into the following four sections:

ESSENTIAL TERMS
Core vocabulary for all publishers.

COLOUR TERMS
Used for scanning, proofing and printing.

IMAGING TERMS
Technical words for digital imaging.

PRINTING TERMS
Some giclée printer's terminology.
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