Adobe
Monitor Setup.
see AMS.
Aliasage
Phenomenon which makes the pixels visible, in particular
on the level of the diagonals and the curves, their
giving the aspect of a crênelage. One speaks about
the effect of staircase. Contours are not smooth any
more but appear in teeth of saw.
AMS
Characterization of color file for monitor used by the
color management system of Adobe Photoshop software.
ANSI
American National Standards Institute. American national
institute of the standards.
Analog to digital converter
Component of a scanner. Converts the analogical electric
signals into exploitable numerical signals by a computer.
Autocorrection of the tonalities.
One of the automatic functions of the majority of the
scanners or the software. If, at the time of the analysis
of the original document, a nonuniform distribution
of the pixels is noted, the apparatus carries out a
widening of the range of the tonalities in order to
optimize the image.
Automatisms
Automatic functions carried out by the scanner or the
software, for example:
Distortion of the curve of gradation
Correction of the range of the tonalities
Bit
Smaller unit of information.
Basic unit for all the operations carried out by a computer.
Comparable with a switch knowing only two states: High
or low, that is to say 1 or 0.
Bitmap
Digitial image made up of many small squares called
pixels.
Black Body.
Theoretical object absorbing the totality of incidental
radiations. So the light emitted since a black body
comes only from him and was not considered.
Brightness
Measure intensity (brightness) of a source of light,
generally expressed in Candelas per square meter (Cdm2)
or feet Lamberts.
Calibration
Process consists of syntonizing all the components of
the system like the monitor, the scanner and the printer.
Candelas (cd)
International unit of measurement of the light intensity.
Brightness can be expressed in Candelas per square meter
(Cdm2).
Cathode ray Tube
to see CRT
CCD Sensor
Charge-coupled device. Component of any flat scanner;
essential for the transformation of the signal. It is
here that the conversion of the light signals into electric
signals takes place.
Chromatic model
System allowing to describe the colors. Examples: RGB,
CMYK, CIELAB, CIELUV.
Chromatic profile
It acts of a standardized profile used to define the
colour spaces of the equipment of seizure, of representation
and exit, i.e. the scanner, the monitor and the printer.
CIE
Commission internationale de l'Eclairage the
commission has the role of defining standards for the
color and lighting and worked out the chromatic system
standardized XYZ of the CIE in 1931 and the chromatic
system Lab.
CIELAB
Space chromatic standardized in three dimensions worked
out by the Co in 1976. "L *" represents the
luminosity, "A *" represents the co-ordinate
of the color on the axis Rouge/Green and "B *"
represent the co-ordinate of the color on the axis Jaune/Blue.
Lab space (as it is often called) is linear according
to perception, this fact two colors close one to the
other have close co-ordinates numerically.
L*: variable of clearness
L*= 116 [Y/Yn]1/3 - 16
A * and B *: co-ordinates of chromaticity:
a* = 500 [(X/Xn)1/3- (Y/Yn)1/3]
b* = 500 [(Y/Yn)1/3 - (Z/Zn)1/3]
CIE-L*u*v*
Colorimetric space relative to a reference of white
created in 1976. CIE-L*u*v space * is linear according
to perception, this fact two colors close one to the
other have close co-ordinates numerically.
CIE-uv (coordonnées chromatiques)
Co-ordinates of a color in colorimetric space CIE-L*u*v
*.
?E*uv = v[(?L*)2 + (?u*)2 + (?v*)2 ]
CIE-xy (coordonnées chromatiques)
Co-ordinates of a color in colorimetric space CIE-xyY.
CIE xyY
Standard independent colorimetric space very much used.
"Y" represents Brightness, "X" and
"there" represent the co-ordinates of the
color considered.
CMYK
Basic colors for the impression in quadrichromy: cyan
magenta, yellow and black. You will find sometimes abbreviation
English CMYK (Cyan, Magenta, Yellow, Black)
CMS
Abbreviation of Color System Management. Software used
to manage the color at the time of the passage of elements
of the numerical chain of image processing to another
(scanner, monitor, imprimante').
Coefficient of enlarging
This coefficient indicates in which proportions the
original must be increased on the image posted on computer.
From a mathematical point of view, this coefficient
is obtained by dividing the format of exit by the initial
format. If one increases an original of format 3 X 3
cm with a format of 9 X 9 cm, the coefficient of enlarging
will be 3 (that is to say 300 %).
Colorimeter
Apparatus optronic (optical and electronic) of measurement
of the color by the analysis of the light emitted or
reflected according to three channels Red, Green and
Blue (sometimes more).
Colorimetric space
This known as of a system of representation of the color
according to several dimensions. Colorimetric spaces
are often three-dimensional (like spaces RVB, CIE-xyY
or CIE-L*a*b * for example).
Color Management System
see CMS.
ColorSync
System of management of the color developed for the
APPLE computer.
Commission internationale
de l'Eclairage.
see CIE.
CRD
Color Rendering Dictionary (Dictionary of returned colors).
Used especially in RIP.
CRT
Abbreviation of Ray Cathode Tubes. Tube glass forming
the screen of posting of the monitors. An electron beam
irradiates phosphorus covering the interior of the tube
to emit light and to form an image.
D50 Daylight.
It is a term to identify a source of light which emits
with a temperature of color of 5000 Kelvin degrees.
darkest zone
On an original document, it acts of the zone darkest
(but not necessarily black) having to be
reproduced, and often that having the highest density.
DE
Value translating the variation of perception between
two colors and allowing to define how much these colors
are close or distant. OF is given by calculating the
distance which separates two colors in colorimetric
space CIE-L*u*v *. One FROM 1 indicates the beginning
of a difference in perception
between two coleurs.
Density
The degree of impermeability of layer of color to the
light. Mathematically speaking, it acts of the logarithm
of opacity. Concept of opacity and density.
Depth of bits
The number of bits describing defines a pixel. Determine
the number of levels of gray which can be represented.
Colorimetric representation of the space of a lumieuse
source. There are several methods to describe numeriquement
a source of light (then also a screen). It include the
co-ordinates xy, co-ordinates UV of space Co 1960 UCS,
the co-ordinates u*v * of space Co 1976 UCS, the temperature
of color. Space CIELUV is sometimes used. Like it calls
upon a point of origin, it is imperative to determine
before the standard light before use of this system.
Detramage
Technique used in order to avoid the effects of watered
effect. The woven documents are analyzed by a sampling
apart from the zone of clearness of the scanner what
makes them fuzzy. The re-establishment of the clearness
of the image is then automatically carried out on computer.
Device-dependent
This known as of a colorimetric space on which returned
color is dependent on a given element (like a peripheral
for example). Colorimetric space RVB, for example, is
depending amongst other things on the characteristics
of the phosphorus used by the monitor. Colorimetric
space CMJN is depend inter alia characteristics on the
inks and paper used for the impression.
Device-independent
This known as of a colorimetric space able to return
account of a color whatever the characteristics of the
elements of the numerical chain of image processing.
CIE-xyY space makes of it in particular party.
Dispersed light
On images where clear zones and dark zones are côtoient,
it may be that the light reflected by certain clear
points is dispersed and detected by sensors CCC neighbors.
These points thus adopt by error a too clear value.
The digitized result is then faded. In the case of scanners
flat, where digitalization is carried out line not line,
this risk is greater than in the case of drum scanners
where the original document is digitized point by point.
Digital camera
Apparatus with special back panel on which CCD sensors
are laid out in the form of a matrix. It thus allows
a direct digitalization of bulky objects in three dimensions,
adapted for a scanner.
Digitalization
itself with all the final adjustments.
Distortion of the gradation
The scanner can proceed to a distortion of the curve
of gradation in order to adapt the image in RVB to the
perception of our eye.
Document with dominant of
color
Document presenting any balancing of the colors or a
predominance of a certain color, like the old yellowed
photographs or the stereotypes of sun couchers.
Document with flutters
Original document on which one can observe small reflexions
which form clear surfaces (or flutters), as on glasses
of glasses or on the surface of water points. One finds
sometimes the term English "Catchlight".
Document with the feature
These documents exclusively contain black or white pixels
and any level of gray nor of colors. The text that you
are reading is thus also a document with the feature.
Document color
Image color represented for example in the form of slide
or of photo stereotype.
Document in levels of gray
Called in general image in black and white. All the
colors are represented in the form of différenteséchelles
of gray.
Document test IT8
Document color standardized intended for the calibration
of the scanner. Calibration of the system
Document High Key
Image which, from the reason represented, very clear
and is contrasted little, like a polar polar bear in
snow for example.
Document Low Key
Image which, from the reason represented, very dark
and is contrasted little, and of weak range of tonalities,
like a black plate on a tablecloth dark blue for example.
dpi
Of English Dowries per Inch (points per inch or PPP)
Measuring unit of the resolution of a peripheral of
exit, like a printer or flasheuse. Also used to indicate
the resolution of digitalization. The metric unit dpcm
(Dowries per centimeter/points per centimetre) only
is seldom used. The scanners of good quality enable
you to choose between these two units. 1 dpi = 1 dpcm
X 2,54
Duv
Value translating the variation of perception between
two colors independently of Brightness. Duv is used
to determine how much a white point is near or not to
the curve of the places of the black bodies. Coordonées
CIE-UV are preferred in coordonées CIE-xy because
they are linear compared to perception.
Effect of
mottled
(in English Speckling) Just like the effect of clouded,
this phenomenon is noted when y has an excessive stressing
of the clearness of the original document. The most
negligible irregularities of the image become visible,
or one can observe clear pixels isolated in dark zones,
phenomenon resulting from the generation of noise.
EPS
of English Encapsulated Post-script Format of file used
in the sector of the CAM. A file EPS is composed of
a main file comprising of the summary data of visualization
of the image and distinct files containing the detailed
data for each extract of color.
Effect of clouded
(in English Mottling) appearing Effect on all surface
of the image and often generated by a stressing of clearness.
Various pixels, even the grain of film, are made visible.
Effect of halation
It can be obtained by an excessive reinforcement of
clearness. Halations are formed around the zones with
flutters. Clear surfaces are thus extended and there
is less of details represented on the image.
Effect of watered effect
Occurs at the time of the digitalization of woven documents.
It is generated by superposition of various screens,
as the screen of analysis of the scanner by sampling
and the screen of impression of the original document
for example. Results in the observation of lines or
small stars on the image. The image takes the structure
of fabric, as if it were woven.
Factor of
tramage
Parameter included in the calculation of the resolution
of digitalization in order to optimize the result, when
the digitized image is intended for an impression with
screen. To obtain a raised quality, the factor of tramage
should always be of 2.
Feet Lamberts (fL)
Measuring unit of Brightness. Not Blanc usually Definite
the white purest that a monitor can post. The color
of this white point is expressed by the value of temperature
of color.
Final digitalization
Last phase of digitalization after the digitalization
of overall picture and the prenumerisation.
Gradation/
Gamma
Indicate the relation, at the time of the handling of
an image, between the values of entry and the values
of exit. In the case of a standard adjustment, the value
of entry is equal to the value of exit.
ICC ' Abbreviation of International
Color Consortium. Group resulting from
the industry of the color developing of the standards
for technologies of management of the color.
Influence temperature
A scanner, a screen, a printer will be different according
to their temperature. It is nécesaire to let
heat the machines before gauging them or caracteriser.
Sometimes, losque the temperature of a product varies,
its color changes. This phenomenon apelle thermochromism.
To increase the precision of measurements, or of the
reproduction, it is necessary to carry out them in a
part at constant temperature after the product was also
stabilized with tempèrature of the part. It is
necessary to pay attention with charters IT8, if the
scanner has a high temperature. In this case, it fauf
to pay attention not to leave the charter too a long
time in the scanner.
Interpolation
Process which consists in increasing the resolution
beyond the maximum physical resolution of the scanner
and which makes it possible to carry out greater enlargings.
New pixels are added to the existing pixels. Their chromatic
value is calculated according to the neighbouring pixels.
Kelvin
Scale of absolute temperature based on the absolute
zero (0° Kelvin) correspondent with ' 273° Centigrade
Lab ' to see CIE-L*a*b *. Place of the black bodies
' Curves formed by the whole of the points relating
to the color emitted by a black body has various temperatures.
Lines of Isotempérature Lignes represented in
a diagram color (as CIE-UV) is which represents the
whole of the white points whose color seems visually
equal to that emitted by a black body. Outline of screen
Indicates, at the time of the impression, the number
of lines of screen in a given zone. This zone can be
expressed is in lines per inch (lpi = lines per inch),
maybe in lines per centimetre (lpcm), but more rarely.
A screen of 60 corresponds to 60 lines of screen on
one centimetre (60 lpcm), what is equivalent to a screen
of 150 in lines per inch (1 inch = 2,54 cm). More the
lines are tightened, better will be the quality of the
impression, but it will be all the more difficult to
control it.
Look Up Table
to see LUTE
lpi
Of English lines per inch (lines per inch) Measuring
unit of the resolution of the image at exit. In this
case, it is indicated the number of lines which the
image in a given zone comprises (on 1 inch) (or 1 centimetre,
one speaks then about lpcm or lines per centimetre,
but this measuring unit is more rarely used).
LUT
(Look up table) Table of correspondence enters of the
values of entry and exit used mainly the video charts.
Maximum Overprint
which indicates the maximum sum of the 4 colors in impression
CMYK. "maximum covering of surface"
Meter of screens.
Used to measure the outline of screen. The meter of
screens is posed on the original document.
The outline of required screen is located in the zone
where one notes an effect of watered effect.
Noise
It is not a question of the noise which the scanner
makes. It is defined as the electric disturbances thus
being able to result in an inaccurate reading of certain
pixels.
Opacity
Degree of impermeability of layer of color to the light.
Opacity is calculated by dividing the intensity of the
light projected by the volume of light which the original
document reflects or lets cross.
Opaque document
Document which reflects the projected light, like a
photograph or a newspaper cutting for example.
Patch
Square of color (printed paper form by the printer,
read by the scanner, posted by the screen), who contains
a color of reference which is measured and then compared
with the value of reference.
Phosphorus
Materials which emits light as it is bombarded by a
radiation a certain wavelength. The CRT contain three
type of phosphorus laid out on surface of the screen
which emit of the Rouge light, Green and Blue.
Proof Software.
Prévisualisation on a monitor of returned which
an image will have on
a system of impression
Point of screen
Point elementary at the time of the process of the impression.
A point of screen consists of several points of the
image, those being able to be only black or white. More
the point of screen must be dark, more there will be
blackened points of image.
Postérisation
Phenomenon consisting in widening the range of the tonalities.
The tone dark are obscured more still, and the tone
lights cleared up simultaneously, making disappear certain
levels from gray. The histogram corresponding to this
image presents gaps, there is a break in the transition
the tone. Contrasts with the image are widened being
able to make disappear certain details.
Profile ICC
File Profile respecting the standard defined by International
Color Consortium (ICC).
Range
of tonalities
For each original document, it is possible to work out
a histogram on which 256 bars are deferred corresponding
to the various tonalities of gray. The height of the
bar indicates the number of pixels adopting this tonality
of gray. The distribution of the bars, the dark one
with light, indicate the range of the tonalities of
the document. By way of example, a document High Key
will present a very restricted range of tonalities since
practically all the pixels will be located in the clear
zone.
Resolution of digitalization
Indicate the number of different samplings having to
be carried out to analyze a given zone. It is measured
in dpi (of English dowries per inchs/ points per inch
often indicated "PPP") or in dpcm (of English
dowries per centimeter/ points per centimetre), this
metric unit being however employed only very seldom.
In general, more the resolution of digitalization is
raised, better will be the quality of the image posted
on the computer.
RGB
Red, green and blue. Primary colors of a monitor or
a scanner. If each color is present at 100 %, a white
light is obtained. You will find sometimes abbreviation
English RGB (Red, Green, Blue).
Saturation.
Expression of the purity of a color compared to a of
the same gray
luminosity. For example a sharp red is a saturated color,
a pink is in fact a désaturé red, and
a white has a saturation null drum Scanner With this
type of
scanner, the documents are placed on a cylinder and
are analyzed by sampling
point by point.
Spectrocolorimeter.
Apparatus allowing to measure the components of a color.
The spectrophotometer splits up each color in its chromatic
components
which can then have left individually with the values
measurement
CIELAB, for example. Additive synthesis of the colors
Recombining of a color by the
addition of several coloured sources of light. It is
the principle of operation of the monitors which créentle
white
by addition of Rouge light, Green and Blue emitted by
phosphorus
Standard document
Original document which does not present any characteristic
(what does not want to say ordinary or banal). One finds
them in the form of slides or of photo stereotypes,
and their distribution of the tonalities is uniform.
They are consequently easy to digitize, generally automatically.
Stressing of clearness
Process also called as "vague masking" (in
English Unsharp masking - USM). It is a technical process
allowing the development of the original document by
accentuating the clearness of contours on the image.
Subtractive synthesis of
the colors.
Recombining of a color by the subtraction of a part
of the light of
illumination. It is the principle of operation of the
printers which create the
black by the subtraction of Rouge light (captured by
Cyan ink), Green (captured by Magenta ink) and Blue
(captured by Yellow ink). Noir ink is used in complement
to increase the suppression of Surexposé light,
under exposed original Document which, not because of
its reasons but because of a technical defect, is too
dark (under-exposed) or too clearly (over-exposed).
Temperature
of Color
Color of the light emitted by a black body when it is
brought up to a given temperature (expressed in Kelvin
degree) Temperature of Color in Température correlation
of color expressed nearest in Kelvin degrees for a white
point which is not exactly on the curve of place of
the black bodies
Tiff
Abbreviation of the English denomination Tagged Image
Spins Format. The format of image most used and supported
by all the usual systems. This format is thus particularly
suitable for the data exchange.
Tonal Curve
Graph representing the relation between the values
of entry and exit of a system or a given peripheral.
This graph can in particular represent the correspondence
between the values of a colorexpressed in a software
in RVB and the luminous result on the surface of the
screen.
Total Ink limit
to see: Overprint Maximum
Transparent document
Document which lets cross the light, like the slides
or the negative ones.
Tube photomultiplier
Component of a drum scanner in which the light signal
which penetrates there is converted into an amplified
electric signal then.
Variation
of density
Corresponds to the difference between the highest level
of density and the lowest level of the density of a
document. For the opaque documents, it is in general
about 2,0 D and of 3,0 D or more for the transparent
documents.
Woven
document
Original document in levels of gray or color presented
in printed form and thus woven.
Zone
of high lights
On an original document, it acts of the zone most luminous
(but not necessarily white) having to be reproduced
and presenting
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