GLOSSARY
Glossary
A
aberration A distortion in an image caused by a flaw in a mirror or lens.
achromatic color A color with no saturation, such as light gray.
acquire A software menu selection to scan from within the program (if it is TWAIN compliant).
ADC (analog-to-digital converter) A device that measures electrical voltages and assigns digital
values to them.Airy disc A disc of light caused when a pinpoint of light is diffused to form concentric halos about the
original point.aliasing The noticeable repeated patterns, lines, or textures in any photographed or scanned subject
that conflict with the pattern of an electronic sensor’s pixel arrangement. For example, diagonal lines
represented by square pixels will produce jagged lines.analog The measurement and recording of continuously varying values in the real world, such as
sound, light, and size. The measurements correspond proportionally to other values, such as electrical
voltage. Film cameras are analog devices. See also digital.anti-shake One of several technologies to counteract the movement of a lens and the resulting
blurring of a photo.antialiasing A technique of blending variations in bits along a straight line to minimize the stair-step
or jagged appearance of diagonal edges.aperture The lens opening through which light passes, expressed by a number called the f-number
(or f-stop). Typically, f-stops range from f-2 through f-32, although many lenses don’t reach the extremes
on either end. Each higher number represents an opening half the size of the previous number, with f-2
being the largest opening and f-32 the smallest. The aperture is one of the key factors in an exposure
setting.array A grouping of elements, such as the rectangular array of photodiodes that make up the digital
film that captures an image.artifact An unwanted pattern in an image caused by the interference of different frequencies of light,
from data-compression methods used to reduce the file size, or from technical limitations in the image-
capturing process.200