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Graphics and Design Terms Glossary A - K
Graphics and Design Terms Glossary
A — K
Knowing graphics and design terms are important because "speaking the same
language" always helps things along. For both clients and novice designers it is
important to be aware of graphics and design terms and expressions to ensure that
projects are being both designed and quoted properly. For instance a grayscale
image looks black and white ... yet in terms of creating an image, the differences
between a black & white and gray scale image is considerable!
For these reasons this glossary of terms will help ensure clear communication,
accurate project quotes and expected results
Fees may vary depending upon whether the agreement
is a "one-off" or package / development project
...no different than a "volume discount."
Light without color. The quantity of light is the only attribute associated with
achromatic light. In physical terms this is the intensity or luminance or in the
psychological sense it is the perceived intensity in which case the term brightness is
Additive Color Model :
In an additive color model, colors are defined as a sum of contributions from primary
colors. The most commonly used additive color model is the Red-Green-Blue model
and is used by computer monitors to produce their display.
Additive Primaries :
Red, green, and blue (RGB). Lights of these colors, when mixed together in varying
intensities, produce any other color in the additive color model.
Alpha Channel :
The top byte of a 32-bit pixel that is used for data other than color. The channel may
hold mask or transparency data.
Ambient Light :
A global (artificial) illumination level representing infinite diffuse reflections from all
surfaces within a scene ensuring that all surfaces are visible (lit) particularly those
without direct illumination.
(1) A medium that provides the illusion of a moving scene using a sequence of still
(2) Techniques used in the production of animated films. In computer graphics this
primarily concerns controlling the motion of computer models and the camera.
Anti-aliasing is a method of reducing or preventing aliasing artifacts when rendering
by using color information to simulate higher screen resolutions. In one technique,
blurred pixels are introduced by filtering the image, or individual elements. The
blending of pixel colors on the perimeter of hard-edged shapes, like type, to smooth
out undesirable edges (jaggies).
Artifacts / Artifact :
A classifiable visual error. E.g., a loss of resolution when zooming into an image or
incorrect depth sorting due to the painter's algorithm.
(American Standard Code for Information Interchange) A standard editable format
for encoding data.
Aspect Ratio :
The ratio of the width of an image to its height (x:y). For example, the aspect ratio of
an image 640 x 480 pixels is 4:3.
Atmospheric Effects :
Atmospheric conditions or phenomena that effect the clarity or mood of a scene. Fog
and smoke are examples of atmospheric effects.
The Hypothetical linear path. The X, Y, and Z axes (width, height, and depth,
respectively) define directions of the 3D universe. The axis along which an object is
rotated is the axis of rotation.
A picture that is automatically composited behind a 3D scene. The matte paintings
used in traditional movie making are an example of backdrops.
Bezier Curve :
(1) A spline curve that (in the usual case of a cubic Bézier curve) is represented by
four control points defining a cubic polynomial.
(2) A curved line segment drawn using the Pen tool that can be reshaped by
manipulating its anchor points or direction lines.
In PhotoShop, it is a method for encoding data. Binary encoding is more compact
than ASCII encoding.
Binary Digit :
A binary digit is the smallest unit of information on a computer. Eight bits equal one
Bit Depth :
The number of bits used to define the shade or color of each pixel in an image. A 1-
bit image is black and white. An 8-bit grayscale image provides 256 shades of gray.
An 8-bit color image provides 256 colors. A 24-bit image provides over 16 million
colors: 8 bits are used for red, 8 are for blue, and 8 for green.
Bits per Pixel :
The number of bits used to describe the color or intensity of a pixel. For example,
using 8 bits for to store a value from the RGB color model would permit 3 bits to be
used for both red and green values and 2 bits for the blue value. Blue gets a smaller
range because the human eye contains less blue cones and is thus is less sensitive
to blue variations.
Strictly a one-bit-per-pixel representation for a defined area of a display. In
PhotoShop, Bitmap is also a one-channel mode consisting of only black and white
Reduces areas of high contrast to soften an image.
An object created by combining two objects using mathematical operators. The two
object may be subtracted from each other, merged, or intersected to form the new
Bounding Box :
The smallest regular shaped box that encloses an object, usually rectangular in
(1)The perceived intensity of a radiating object.
(2) The amount of light reflected by a surface.
(3) The intensity of a light source.
(4) The luminance of a color.
Traditionally in art, a brush is an implement that has hairs or bristles firmly set into a
handle and used to paint with. In Photoshop, Painter and other computer graphics
applications the brush is a virtual tool replicating the functions of its real world
counterpart. Virtual brushes (depending on the program used) can emulate anything
from a hard edge pencil, to soft edge airbrush effects, to crayons, oils, watercolor or
even impasto style strokes. In most programs you usually have control over the
characteristics of the brush stroke and you can also create custom brushes. When
using pressure sensitive devices such as a graphics tablet, different characteristics
of your brush stroke such as width and opacity can be controlled by factors such as
pressure and pen tilt (depending on the device).
Bump Mapping :
A technique used to increase the realism of a surface by changing how light reflects
from that surface. Usually, the surface normal at a given point on a surface is used in
the calculation of the brightness of the surface at that point. Part of what gives this
techniques its appeal is that the original surface maintains its original (usually
smooth) shape, and the bump-mapping distortion is specified by a compact function
of shape. This is usually much simpler and more compact than specifying the
surface texture by explicitly representing the textured surface.
A PhotoShop tool that is used to darken an area of an image.
Abbreviation of Computer Aided Design. In the context of graphics, CAD refers to
the use of computer based models of objects for visualization or testing as an aid in
the design process.
The process of setting a device to known color conditions. Calibration must be
performed externally for devices whose color characteristics change frequently. For
example, calibration must be performed on monitors because phosphors lose
brightness over time, and on printers because proofers and other digital printing
devices can change output when colorant or paper stock is changed. Calibration is
not required for most input devices (e.g., scanners and cameras) since these
devices are generally self-calibrating.
A virtual viewpoint in world space with position and view direction to provide a view
of a scene in the same way as a photographer would position a camera.
A two-dimensional region of graphics information. The canvas may be displayed on
screen or be recorded in off-screen display memory.
Canvas Size :
The full editable area of an image.
The concentrated light reflections caused by refraction through a transparent
An image component that contains the pixel information for an individual color. A
grayscale image has one color channel, an RGB image has three color channels,
and a CMYK image has four color channels.
(1) A characterization of how much a color differs from both the pure color and the
grey of the same intensity. Also called saturation.
(2) The color component of a composite video signal.
(3) The quality of a color that is the combination of hue and brightness. In the
Munsell system of color notation, chroma indicates the purity of a color as measured
along an axis; the farther from the axis, the purer the color.
An area of memory used to temporarily store selection pixels. The Clipboard is
accessed via the Cut, Copy, and Paste commands.
(1) The selective removal of an object disjoint with the display area or the non-visible
parts of an object that does intersect the display area. Parts of an object intersecting
the display area may lie outside of the display area or be partially or fully obscured
by another intersecting object.
(2) Color shift caused by the inability of one color space to reproduce all the colors
of another color space.
(3) In PhotoShop, the automatic adjustment of colors to bring them into printable
(Cyan, Magenta, Yellow, and Black) The four-ink colors used in process printing.
Cyan, magenta, and yellow are the three subtractive primaries. CMYK colors are
simulated on a computer monitor using additive red, green, and blue light. To color
separate an image from PhotoShop, convert it to CMYK Color mode.
Algorithms used in multimedia. Stands for Compression/Decompression.
Color Correction :
The adjustment of color in an image to match original artwork or a photograph. Color
correction is usually done in CMYK Color mode in preparation for process printing.
Color Keying / Chroma Keying :
Using the pixel color of one image to designate that pixel data from another image
should replace the first pixel's color. The first image might be a binary image, which
would select regions of interest from the second image. Another use is in blue-
screening, where an actor works against a blue background. In the output image, the
blue pixels get replaced by another image. For example, a weather map can be
placed behind the weather presenter who is actually standing in front of a blue
Color Models :
A color model is a method of specifying a color (position) in color space, often using
a co-ordinate system. Examples include RGB and the Munsell Color System.
Color Separation :
The production of a separate printing plate for each ink color that will be used to
print an image. Four plates are used in process color separation, one each for Cyan,
Magenta, Yellow, and Black. An addition plate is used for each spot color.
Color Space :
A mathematical space defining a range and encoding of colors. E.g. see RGB, LUV,
HSV, HSL, YIQ, YUV and XYZ.
Color Table :
The color palette of up to 256 colors of an image in Indexed Color mode.
Composite Printer :
The printer used to make a composite color image of a file. This printer can be used
for proofing or for final output.
The process of combining multiple images into a single image. Usually this is
performed in films to make a computer graphics generated character appear on a
previously filmed background. The term is also used in traditional photographic
manipulation to refer to the process by which cell animation is recorded onto film
under a rostrum camera. In film the 'mechanical' process is usually called matte
photography (see color keying), and the process, when used in film sequences is
ambiguously called traveling matte.
The process by which some of an image's data is either stored in patterns or
eliminated in order to reduce the images file size.
Continuous-Tone Image :
An image, such as a photograph, in which there are gradual transitions between
shades or colors.
Contract Proof :
The proof (e.g., Dupont WaterProof or Imation MatchPrint) of a color printing job that
is the basis of a contract between a printer and a client. The appearance of the
contract proof should represent the appearance of final printed piece.
The range of colors in an image. Increasing the contrast of a color palette makes
different colors easier to distinguish, while reducing the contrast makes them appear
A tool used to trim away part of an image.
Crop Marks :
Short, fine lines that are placed around the edges of a page to designate where the
paper is to be trimmed at a print shop.
Data Rate :
Transfer speed of a specific device.
DCS 2.0 :
(Desktop Color Separation) A file format for saving a CMYK image for color
separation, with the option for saving spot color channels and alpha channels, and
an optional low resolution file for previewing and laser printing.
Depth of Field :
The distance between the closest and farthest objects in focus within a scene as
viewed by a lens at a particular focus.
Light that is reflected from an object's surface, regardless of the angle from witch its
An animation effect that is a transition between two sequences involving a fade from
one directly to the other.
The mixing of adjacent pixels to simulate additional colors when available colors are
limited, such as on an 8-bit monitor or an 8-bit palette.
One of many processes for reducing the total number of colors present in an image
while retaining visual fidelity. Dithering can be done by interleaving pixels of selected
colors to locally approximate the desired color. Dithering can be applied to either a
color or a grayscale color space and may be necessary due to a limited number of
colors available on the display device.
To bleach (lighten) an area of an image.
Dot Gain :
Measured by the increase in size of a mid-tone dot, the spreading of dots during
plate-making or on a printing press as wet ink is pushed into the paper and possibly
absorbed by it, which causes colors or shades to look darker.
(Dots per inch) A unit that is used to measure the resolution of a printer or image
setter. Dpi is sometimes used to describe the input resolution of a scanner, but "ppi"
is the more accurate term.
A grayscale image that is printed using two plates to enhance its tonal depth.
A standard 3D file format that was originally developed by Autodesk to exchange
CAD data between various software applications. This format only offers support for
basic geometric information.
Dye Sublimation :
A continuous-tone printing process in which a solid printing medium is converted into
a gas before it hits paper.
EPS : Encapsulated PostScript, the file format based on Adobe PostScript. Primarily
used to define vector graphics (i.e., geometrical shapes), it can also be used to
contain and provide instructions for rendering image (i.e., pixel-based) data. In the
case of PhotoShop, an optional PICT or TIFF image for screen display is included
too. EPS is a commonly used format for moving files from one application to another
and also for color separation.
Fades an area over a specified number of pixels.
Fill/Flood Fill :
These are techniques for coloring areas bounded by line edges. The algorithms that
fill interior-defined regions (the largest connected region of pixels whose values are
the same as a given starting pixel) are called flood fill algorithms.
1) An optical device that selectively attenuates the intensity of light passing through
it according to the light's properties. Common filters attenuate light according to
either wavelength or polarization state.
2) An algorithm that selectively modifies the intensity or color of image data
according to the image's properties. 3) An element (software or hardware) which
takes in a stream of data and produces a stream of results, on average one output
for each input.
Foreground Color :
The color that is applied when a painting tool is used, type is created, or the stroke
command is applied.
Four-color Process :
The printing process that reproduces colors by combining, cyan (C), magenta (M),
yellow (Y), and black (K) inks. This process is alternately called four-color printing,
CMYK printing, or process printing.
FPS : Frames Per Second. The rate at which animations are displayed.
A still two-dimensional image. Often a frame is a raster image as used in the frame
buffer of a graphics display system. In computer animation frames per second is a
measurement of the number of still frames displayed in one second to give the
impression of a moving image.
Frame Rate :
The frame rate of a video source is determined by the speed at which it completes
the rendering of a new image. This is limited by both the speed at which image data
can be created and the rate at which video images can be presented on a display.
For example the NTSC system redraws at 30Hz, PAL is 25Hz and computer displays
are now usually 72-75Hz.
Frame Size :
A term used to refer to the dimensions of the array of pixels forming a frame of an
animation, or alternatively the memory requirement and hence indirectly the
resolution and dimensions.
The values produced by a monitor from black to white are nonlinear. If you graph the
values, they form a curve, not a straight line. Gamma defines the slope of that curve
at halfway between black and white. Gamma adjustment compensates for the
nonlinear tonal reproduction of output devices such as monitor tubes.
The total range of colors produced by a device. A color is said to be "out of gamut"
when its position in one device's color space cannot be directly translated into
another device's color space.
Graphic Interchange Format. This file format is commonly used on the internet.
Gradient Fill :
In PhotoShop, a graduated blend between the Foreground and Background colors
that is produced using the Gradient tool.
A color space where colors are represented by their luminance values only, i.e.
saturation and hue are zero. An image that contains black, white, and up to 256
shades of gray, but no color In PhotoShop, Grayscale is a one-channel image mode.
Halftone Screen :
A pattern of tiny dots that is used for printing an image to simulate continuous tones.
Hard Proof :
The printed proof of a document created to preview how colors will look when
reproduced on a specific output device, usually a commercial printing press. A hard
proof may be produced using a laminate contract proofing system (e.g., Imation
MatchPrint) or a tightly calibrated digital printer designed for proof creation.
Highlight : The area of a glossy object over which specular reflection can be viewed.
It is normally the color of the light source, not of the object.
A graph showing the number of pixels at each level of brightness in an image.
A three-coordinate, device-independent color model. The HSB coordinates define
colors in terms of Hue, Saturation, and Brightness.
HSL, also known as HSI (Hue-Saturation-Intensity) is a color space used to
represent images. HSL is based on polar coordinates, while the RGB color space is
based on a three-dimensional Cartesian coordinate system. Intensity is the vertical
axis of the polar system, hue is the relative angle and saturation is the planar
distance from the axis. HSL is thought to be more intuitive to manipulate than RGB
space. For example, in the HSI space, to change red to pink requires only changing
the saturation parameter.
A color space that describes color using three basis components: hue, saturation
The wavelength of light of a pure color that gives a color its name--such as red or
blue--independent of its saturation or brightness.
The amount of light falling into a patch of unit surface area. It is measured in lux.
A high-resolution printer (usually between 1,270 and 4,000 dpi) that generates paper
or film output from a computer file.
Image File Format :
A representation (usually binary) used by a computer system as an agreed format to
store an image. Examples of image file formats include the Graphics Interchange
Format (GIF) and Tagged Image File Format (TIFF).
Inbetweening is the generation of intermediate transition positions from a given start
and end point or keyframes. This technique is often used in animation, where a lead
artist generates the beginning and end keyframes of a sequence (typically 1 second
apart), a breakdown artist does the breakdowns (typically 4 frames apart), and an
‘inbetweener’ completes the rest.
Indexed Color :
In PhotoShop, an image mode in which there is only one channel and a color table
that can contain up to 256 colors. All the colors in an Indexed Color image are
displayed on its table.
Indexed 16 and 256 Color Images :
An indexed color image consists of a set of references to values stored in a color
table or palette. The palette, which is often contiguous in an image file, lists all the
colors as sets of coordinates in color space. An indexed 16-color image contains a
palette with 16 color entries (4 bits), whereas in an indexed 256 color image 256
colors are listed (8 bits).
A process that occurs automatically when an image's dimensions or resolution are
changed which results in re-coloring the pixels. Interpolation may cause an image to
look blurry when it's printed. You can choose an interpolation method in PhotoShop
from slower, but better, to faster but lower quality.
Interlaced Display :
A technique for displaying images at a higher resolution than the monitor. Two
images consisting of every second row of pixels are alternately displayed during
every screen refresh (e.g. every fiftieth of a second). There is hence a flickering
International Color Consortium (ICC) :
The group established by eight industry vendors (including Adobe Systems) for the
purpose of creating, promoting, and encouraging the standardization and evolution
of an open, vendor-neutral, cross-platform color management system architecture.
Inverse Kinematics (IK) :
The study of how movement of a body part affects other attached body parts.
To reverse an image's light and dark values and/or colors.
Acronym for Joint Photographic Experts Group. Commonly used to indicate a pixel-
based graphic file format, JPEG is actually a compression method used mostly for
continuous tone images.
An image format commonly used on the internet. It does not support layers,
transparency or alpha channel data.
To adjust the horizontal spacing between a pair of characters.
An image that is stored in some way to be used as a reference point. Key frames are
often used in animation
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