ΔE (pronounced “Delta E”)
Represents the degree of difference between two colours.
Usually quoted in terms of CIE Lab, it is generally considered that
a ΔE of 2 or less is imperceivable visually. In fact, it depends
on the colour to which it applies – neutral tones show change
far more readily than saturated colours.
The density and colour of the darkest black reproducible by a device.
Black Point Compensation
A software setting that maps the black point of the source
profile to the black point of the destination profile.
The adjustment of the behavior of a device to a standard state.
Finding the relationship between visual colour and a device’s
colour before profiling.
Commission Internationale d’Eclairage. An association
of international colour scientists who produced the standards that
are used as the basis of the description of colour.
A device-independent colour space that attempts to uniformly
represent colour as we perceive it. ‘L’ is the lightness
value, ‘a’ is the red/green opponency and blue/yellow
is represented on the ‘b’ axis. It is used as a conversion
space (PCS) when transforming from a source profile to a destination
Colour Management Module, Colour Matching Method or Colour
Manipulation Model, this is the engine which performs the transformation
from one colour space to another. Different CMMs may produce different
A representation of a device in which each colour is described as
a point in space by a tristimulus value. Each individual device
effectively has its own colour space.
A description of the colour of the emissions from a light source
in ‘kelvins’. Lower values are redder, higher values
bluer. The standard colour temperatures for a monitor is 6500ŠK
despite the fact that when delivered they are generally in the 9300ŠK
to 11000ŠK range. A light box or reflective viewing area should
be standardised at 5000ŠK.
The degree to which a surface absorbs light.
A profile that defines how colours are to be converted from the
PCS to the output space (device).
Embedding a profile saves a copy of the source profile with the
file so that the numeric colour values have some ‘meaning’
when taken to the next stage of the workflow.
On a monitor gamma is the relationship between the input voltage
and the output luminance. Device gamma is the degree to which the
device is non-linear in its tonal behavior.
The range of available colours that is reproducible on a specific
output device. The gamut of a printer will be different for different
The re-mapping of colours from one colour space to another.
Giclee printing (pronounced gee-clay)
A relatively new field of printing that is concerned with the accurate
reproduction of artworks from traditional media by means of an inkjet
printer. Usually output to canvas or ‘fine art’ papers.
International Color Consortium. A group of companies who joined
forces to produce a set of standards for profile formats. Most profiles
are ICC profiles.
Image Color Management in the Windows implementation of ICC profiles.
A profile that describes the way an input device (scanner or digital
camera) sees colour. (N.B. A source profile is not necessarily an
The relationship between stimulus and response where an increase
in stimulus will result in a corresponding increase in response.
The process of making a device deliver a linear response. Entails
setting shadow and highlight points and determining the appropriate
More precisely ‘illuminant metamerism’ is where two
(spectrally) different colour samples look the same under a particular
viewing condition but different under another.
A Profile Connection Space is the intermediate colour space that
is used in the transformation from one profile to another.
A file that describes the relationship between visual colour and
device colour of a specific device. There are many types of profile
including input, output, abstract colour space and device link profiles.
The process of ‘fingerprinting’ a device to find the
relationship between visual colour and the device’s colour.
Sometimes called characterization.
There are four different rendering intents – Perceptual, Relative
colorimetric, absolute colorimetric and saturation. Each reflects
a different set of rules for remapping colours between one colour
space’s gamut and another. Perceptual is said to be the best
intent for photographic use because it maintains the relativity
of colour during remapping. It should be used mainly for changes
between spaces of similar size. Relative colorimetric leaves in-gamut
colours alone and pulls out of gamut colours in. This can result
in compression of saturated tones. Absolute colorimetric rendering
is the same as Relative except that it will simulate the white point
in the output this makes it useful only for proofing. Saturation
intent should be ignored.
Soft Proofing Displaying a simulation of the output
of a document on your monitor.
Source Profile Defines how a documents colours
will be converted between the first colour space to the PCS or visual
The process of associating a source profile with a document and
can be achieved either by ‘assigning’ a profile within
an application or embedding a profile as you save it.
The intensity and colour temperature of the brightest white
reproducible by a device. For a monitor this is the colour and intensity
when red, green and blue guns are generating their highest output