Glossary of Terms
The following is a list of industry or technical terms for
digital imaging and photography used on this site, and the
associated definitions.
Aspect ratio
The ratio of the width of an image
on the screen or print compared to its height. An aspect
ratio of 2:1, for example, indicates that the image is twice
as wide as it is high. The aspect ratio is an important
factor in maintaining correct proportions when an image
is printed, rescaled, or incorporated into another document.
Barrel distortion
Means that the image appears to be mapped
around all or part of a spherical object.
Canvas size
The total size of the image including
white space.
Cartographer
An individual who makes maps.
Conical
Having the form of a geometrical cone.
Distortion
Changing the shape, bending or twisting
of something out of its original or natural shape.
Equal area projection
Evenly balanced between opposing sides
Fisheye lens
An ultra wide-angle lens that gives an
extremely wide field of view, normally up to 180 degrees
and beyond.
Full frame fisheye lens
A full frame fisheye lens is defined
as one that covers a 180 degree field from a corner to corner
view of the image.
Hemispheric
Represents one half of a sphere.
Infinity
a. A range in relation
to an optical system, such as a camera lens, representing
distances great enough that light rays reflected from objects
within the range may be regarded as parallel.
b. A distance setting, as on a camera,
beyond which the entire field is in focus.
Invariant
A set of quantities that is not changed
by a designated mathematical operation such as the transformation
of coordinates.
Mapping
Mathematically transforming an image to achieve the desired
effect.
Pincushion distortion
Is the opposite of barrel distortion. The magnification
of the image increases with increasing distance from the
optical axis. The visible effect is that lines that do not
go through the center of the image are bowed inwards, towards
the centre of the image.
Planar
Flat or lying in a single geometric plane.
Projections
An image or picture projected on a surface.
Radial
Spreading out from a common center like the spokes of a
wheel.
Rectilinear
Rectilinear means that all horizontal and vertical lines
are straight.
Rectilinear Correction
Many rectilinear correction methods have projections that
deliver only the center of the full image as was seen by
the lens. About 28% of the captured information is discarded
in this projection.
Render
To translate something from one form into another
Resolution
The level of reproduction of detail offered by a TV or computer
screen or a film image. Generally it is described either
in terms of lines of resolution, or pixels per unit of measurement.
It is the number of pixels in a digital image. This is used
to describe the sharpness or clarity of the image. In general,
the higher the resolution, the more detailed the image (and
the larger the file size will be). Resolution can refer
to digital images, printers, scanners, and computer screens.
Sensor
A detecting instrument or device capable of detecting and
responding to physical stimuli such as light.
Sphere
A three-dimensional closed surface consisting of all points
that are a given distance from a center. Any object similar
in shape to a ball.
Tangent
A given angle in a right-angled triangle, a trigonometric
function equal to the length of the side opposite the angle
divided by the length of the adjacent side.
Tangential
Touching only at a single point, but not crossing or intersecting.
Watermark (visible)
Is a permanent mark that can be seen when the object is
viewed.
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