Graphic Art Dictionary


With every software title you may wind up using, they all apply the same terms, phrases and references to the work.

Understanding what these terms are and how they apply is a very good start to becoming more proficient with the software.

A

Additive Primaries : Red, green, and blue (RGB). Lights of these colors, when mixed together in varying intensities, produce a wide range of color (the spectrum)

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.

Anti-aliasing : Antialiasing 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).

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.

Axis : 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.

B

Backdrop : 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.

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.
Bitmap : 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 pixels.
Blur : Reduces areas of high contrast to soften an image.
Boolean : 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 object.
Brightness : (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.
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.

C

Caustics : The concentrated light reflections caused by refraction through a transparent surface.
Channel : 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.
Chroma : (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.

CMYK : (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.

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 screen.

Color Table : The color palette of up to 256 colors of an image in Indexed Color mode.
Compositing : 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 cel 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.
Compression : 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.
Contrast : 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 washed out

BACK   NEXT