Instruction manual

Glossary
PIKE Technical Manual V3.1.0
256
Gamma Gamma is the exponent in a power-law relationship between video or pixel
values and the displayed brightness.
Each pixel in a digital image has a certain level of brightness ranging from
black (0) to white (1). These pixel values serve as the input for your com-
puter monitor. Due to technical limitations, CRT monitors output these val-
ues in a nonlinear way:
Output = Input
gamma
When unadjusted, most CRT monitors have a gamma of 2.5 which means
that pixels with a brightness of 0.5, will be displayed with a brightness of
only 0.5
2.5
= 0.18 in non-colormanaged applications. LCDs, in particular
those on notebooks, tend to have rather irregularly shaped output curves.
Calibration via software and/or hardware ensures that the monitor outputs
the image based on a predetermined gamma curve, typically 2.2 for Win-
dows, which is approximately the inverse of the response of the human
vision. The sRGB and Adobe RGB color spaces are also based on a gamma
of 2.2.
A monitor with a gamma equal to 1.0 would respond in a linear way (Out-
put = Input) and images created on a system with a gamma of 2.2 would
appear flat and overly bright in non-color managed applications.
GIF GIF = Graphics Interchange Format
GIF is one of the most common file formats used for images in web pages.
There are two versions of the format, 87a and 89a. Version 89a supports
animations, i.e. a short sequence of images within a single GIF file. A
GIF89a can also be specified for interlaced presentation.
Gigabit Ethernet Gigabit Ethernet is an industry standard interface used for high-speed com-
puter networks that is now being adapted as a camera interface. This gen-
eralized networking interface is being adapted for use as a standard
interface for high-performance machine vision cameras that is called GigE
Vision.
GigE Vision GigE Vision is a new interface standard, published by the AIA, for high-per-
formance machine vision cameras. GigE (Gigabit Ethernet), on the other
hand, is simply the network structure on which GiGE Vision is built. The
GigE Vision standard includes both a hardware interface standard (Gigabit
Ethernet), communications protocols, and standardized camera control
registers. The camera control registers are based on a command structure
called GenICam. GenICam seeks to establish a common software interface
so that third party software can communicate with cameras from various
manufacturers without customization. GenICam is incorporated as part of
the GigE Vision standard. GigE Vision is analogous to FireWire's DCAM, or
IIDC interface standard and has great value for reducing camera system
integration costs and for improving ease of use.