ISO 12647-1:1996
(Main)Graphic technology — Process control for the manufacture of half-tone colour separations, proof and production prints — Part 1: Parameters and measurement methods
Graphic technology — Process control for the manufacture of half-tone colour separations, proof and production prints — Part 1: Parameters and measurement methods
Technologie graphique — Maîtrise de procédé pour la fabrication des séparations de couleur en ton tramé, des épreuves et des tirages en production — Partie 1: Paramètres et méthodes de mesure
Grafična tehnologija - Vodenje procesa izdelave rastriranih barvnih izvlečkov, preskusnih in proizvodnih odtisov - 1. del: Parametri in merske enote
General Information
Relations
Buy Standard
Standards Content (Sample)
INTERNATIONAL IS0
12647-I
STANDARD
First edition
1996-I O-01
Graphic technology - Process control for
the manufacture of half-tone colour
separations, proof and production prints -
Part 1:
Parameters and measurement methods
Technologie graphique MaOrise de pro&d& pour la fabrication des
sbparations de couleur en ton tram& des gpreuves et des tirages en
production -
Partie 7: Paramktres et m&hodes de mesure
Reference number
IS0 12647-1: 1996(E)
---------------------- Page: 1 ----------------------
IS0 12647=1:1996(E)
Foreword
a worldwide
IS0 (the International Organization for Standardization) is
federation of national standards bodies (IS0 member bodies) The work of
preparing International Standards is normally carried out ‘through IS0
technical committees. Each member body interested in a sub, ject for which
a technical committee has been established has the right to be rep-
resented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 12647-1 was prepared by Technical Committee
lSO/TC 130, Graphic technology.
IS0 12647 consists of the following parts, under the general title Graphic
technology - Process control for the manufacture of half-tone co/our
separations, proof and production prints:
Part 1: Parameters and measurement methods
- Part 2: Offset processes
Annex A forms an integral part of this part of IS0 12647. Annexes B and C
are for information only.
0 IS0 1996
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
II
---------------------- Page: 2 ----------------------
@ IS0 IS0 12647=1:1996(E)
Introduction
When producing a half-tone colour reproduction it is important that the
colour separator, proofer and printer have previously specified a minimum
set of parameters that uniquely define the visual characteristics and other
technical properties of the planned print product. Such an agreement
enables the correct production of suitable separations (without recourse to
“trial-and-error”) and subsequent production of off-press or on-press proof
prints from these separations whose purpose is to simulate the visual
characteristics of the finished print product as closely as possible.
It is the purpose of this part of IS0 12647 to list and explain the minimum
set of process parameters required to uniquely define the visual character-
istics and related technical properties of a half-tone proof or production
print produced from a set of half-tone separation films. Other parts of IS0
12647 define specific values for these parameters which are appropriate
for specific processes (such as offset or gravure). For some processes
certain parameters are more significant than others and may be specified
as mandatory whilst the remainder are optional. However, in this part of
IS0 12647 all parameters are treated equally.
It is also necessary to distinguish between primary and secondary par-
ameters. This part of IS0 12647 describes only primary parameters.
Whereas primary parameters are defined as having a direct bearing on the
visual characteristics of the image, secondary parameters only influence
the image indirectly by changing the values of primary parameters. Secon-
dary parameters include
- colour separation film thickness;
- image orientation (wrong-reading or right-reading);
- film polarity (negative or positive);
- roughness of the emulsion surface;
- presence of colour marking or register marks.
Where necessary, for specific process applications, secondary parameters
may be specified in addition to primary parameters but they are not in-
cluded in this part of IS0 12647 except in the definitions.
During the process of colour separation for multi-colour half-tone printing, a
set of half-tone separation films is normally produced from a multi-coloured
continuous-tone original. This usually consists of a photographic trans-
parency or a reflection copy print though any graphic material, in analogue
or digital form, may be used.
The process of colour separation does not provide a unique transformation
of the colour values of the original into those of the production print. For
. . .
III
---------------------- Page: 3 ----------------------
IS0 12647=1:1996(E) @ IS0
every distinguishable spot of the original, the colour (characterizable by
three calorimetric values, e.g. X, Y, Z or L*, a*, b* or hue, saturation and
lightness) has to be converted into tone values (dot areas) for four or more
process colour separation films. However, in most cases the density range
(and, hence, colour gamut) of the original is wider than that achievable in
press printing. As a result, the colour separation process requires some
degree of interpretation of the original by the colour separator and the
resultant transformation may differ from one original to another.
Whatever freedom there exists for the colour separation process, it is
important that the values of the process parameters of the printing press
to be used for production are taken into account. This is because the
process steps that follow colour separation, namely proofing (on- and off-
press), production of the printing forme (for on-press proofing or pro-
duction printing), production printing and print surface finishing, are
normally carried out with a rigid set of process parameters which include
- the properties of the print substrate;
- the optical properties of solid prints of the process inks;
- the tone value increase curve.
Maintaining consistent values for the parameters at all steps in the process
is important to ensure predictable reproduction. Any unforeseen variation
of these values is usually to the detriment of the visual characteristics of
the image.
The technical background discussed so far shows that the processes of
colour separation and proofing require prior knowledge of the values of the
process parameters encountered in production printing. Since it is virtually
impossible to print all jobs with the same set of process parameters,
irrespective of the type of press, printing forme, or substrate used, there
has to be an efficient information exchange between the colour separator,
the proof printer and the production printer which defines the specific
parameters for that job.
To facilitate the information interchange, this part of IS0 12647 defines a
number of parameters whose values should be specified when a set of
colour separation films, with accompanying proof print, is being ordered.
Specific values for each parameter are assigned in other parts of
IS0 12647; this part is concerned with definitions and test methods only.
Because the proof print is the principal means of communication between
pre-press and printing, it is important that
- the proof print be made using the best achievable simulation of the
intended printing parameters and
- productio n prin ting attem pt to match the visual characteristics of the
approved proof print.
One of the major variations between and within printing processes is
between tone value increase curves (or “dot gain curves”), examples of
which are shown schematically in figure 1. One such curve, with appro-
priate tolerances, may be specified for every process colour for each
specific combination of substrate and printing process.
iv
---------------------- Page: 4 ----------------------
IS0 12647=1:1996(E)
INTERNATIONAL STANDARD @ IS0
Graphic technology - Process control for the manufacture of
half-tone colour separations, proof and production prints -
Part 1:
Parameters and measurement methods
- coldset offset and letterpress proof and pro-
1 Scope
duction printing and off-press proof printing on
newsprint;
IS0 12647 specifies parameters which define printing
conditions for the various processes used in the
- gravure printing;
graphic arts industry. The values of the parameters
specified may be used in the exchange of data to
- screen printing;
characterize the intended printing condition and/or for
- flex0 printing.
the process control of printing by practitioners wishing
to work to common goals.
2 Normative references
This part of IS0 12647
The following standards contain provisions which,
through reference in this text, constitute provisions of
- defines vocabulary and establishes a minimum set
this part of IS0 12647. At the time of publication, the
of process parameters that uniquely determine a
printed four-colour half-tone image. (These apply editions indicated were valid. All standards are subject
to revision, and parties to agreements based on this
to others parts of IS0 12647 as well.) The par-
part of IS0 12647 are encouraged to investigate the
ameters were selected in view of the process
possibility of applying the most recent editions of the
stages “colour separation”, “making of the print-
“production printing” and standards indicated below. Members of IEC and IS0
ing forme”, “proofing”,
maintain registers of currently valid International
“surface finishing” being directly applicable to
proofing and printing processes that use colour Standards.
separation films as input;
IS0 5-2: 1991, Photography - Density measurements
- is directly applicable to proofing and printing from - Part 2: Geometric conditions for transmission
printing surfaces produced by filmless methods density.
and to gravure printing as long as direct analogies
IS0 5-3: 1995, Photography - Density measurements
to film production systems are maintained;
- Part 3: Spectral conditions.
- is applicable to printing with more than four pro-
IS0 5-4: 1995, Photography - Density measurements
cess colours as long as direct analogies to four-
- Part 4: Geometric conditions for reflection density.
colour printing are maintained;
- is applicable to line screens and, where relevant, IS0 13655:1996, Graphic technology - Spectral
to those that do not have regular screen angles or measurement and calorimetric computation for
regular screen rulings. graphic arts images.
CIE 17.4 (1987), International lighting vocabulary.
Other parts of IS0 12647 cover specifications for
individual printing processes or groups of these, such
as
3 Definitions
- four-colour proof and production printing on heat-
For the purposes of IS0 12647, the following defi-
set web, sheet-fed and continuous forms offset
nitions apply.
presses, offset proofing for half-tone gravure;
---------------------- Page: 5 ----------------------
IS0 12647=1:1996(E) @ IS0
NOTE 1 For quantities, the preferred unit is given together 3.9 control strip: One-dimensional array of control
with the definition. By definition, the unit of so-called
patches.
dimensionless quantities is 1.
3.10 core density (on a half-tone film): Transmit-
3.1 achromatic (perceived) colour: Colour devoid
tance density in the centre of an isolated opaque
of hue, in the perceptual sense. [CIE 17.4, 845-02-261
image element such as a half-tone dot or line. Unit: 1.
NOTES
3.11 deviation tolerance: Permissible difference
2 The colour names white, grey and black are commonly
between the OK print from a production run and the
used or, for transmitting objects, colourless and neutral.
reference value.
3 In printing practice, achromatic colours can be produced
either by a single ink or three chromatic inks suitably
3.12 film emulsion orientation: Orientation of a
balanced.
colour separation film relative to the observer with
respect to the emulsion side.
3.2 axis of a screen: One of the two directions in
which the half-tone pattern shows the highest num-
NOTE 7 Normal orientation is emulsion up, i.e. towards
ber of image elements, such as dots or lines, per unit
the observer.
of length.
3.13 film polarity: Positive if clear and solid areas
3.3 chromatic (perceived) colour: Perceived colour
on the film correspond to unprinted and solid areas on
possessing hue, in the perceptual sense. [CIE 17.4,
the print, respectively. Negative if clear and solid
845-02-271
areas on the film correspond to solid and unprinted
areas on the print, respectively.
NOTE 4 The process inks cyan, magenta and yellow are
the chromatic colour inks.
3.14 fringe width (of an isolated opaque image
3.4 CIELAB colour difference; CIE 1976 I,*, a*, b* element): Average distance between the density
colour difference AE&: Difference between two contour lines corresponding to 10 % and 90 % of the
minimum core density specified for the printing pro-
colour stimuli defined as the Euclidean distance
cess under consideration. Unit: urn.
between the points representing them in L*, a*, b*
space. [CIE 17.4, 845-03-551 Unit: 1.
3.15 grey balance: Set of tone values for cyan,
3.5 CIELAB colour space; CIE 1976 L*, a*, b* magenta and yellow on the colour separation films is
colour space: Three-dimensional, approximately uni-
in grey balance if a print produced under specified
form colour space produced by plotting IL*, a*, b* in
printing conditions appears as an achromatic colour
rectangular coordinates. [CIE 17.4, 845-03-561
under specified viewing conditions.
3.6 calorimeter: Instrument for measuring color-
3.16 half-tone film: Film for use with a half-tone
imetric quantities, such as the tristimulus values of a
printing process showing image elements like dots or
colour stimulus. [CIE 17.4, 845-05-I 81
lines.
NOTE 5 A photoelectric calorimeter achieves this by the
analogue integration of the spectral product of object
3.17 hard dot film: Colour separation film with half-
reflectance or transmittance factor, illuminant and filters
tone dots that reproduce reliably in film duplication
which are defined by standard illuminant and the standard
and production of the printing forme.
observer functions. A spectrophotometric calorimeter
achieves this by calculation from the spectral data.
3.18 image orientation: Images are referred to as
right-reading (opposite: wrong-reading) if text appears
3.7 colour separation film: One of a set of black-
as it is intended to be read and images are in the
and-white half-tone films for process printing that
orientation intended for viewing by the end-user.
pertains to one process colour.
NOTES
NOTE 6 There are usually four colour separation films in a
set.
8 The film emulsion orientation requires specification as
well: “emulsion up”, or “emulsion down” is stated.
3.8 control patch: Area produced for control or “Emulsion up” is usually assumed if there is no film emul-
sion orientation statement.
measurement purposes.
2
---------------------- Page: 6 ----------------------
IS0 12647=1:1996(E)
@ IS0
9 A typical reference is “wrong-reading emulsion up” to show the results of the colour separation process
which is equ ivalent to ” righ t-reading emulsion down”.
in a way that closely simulates the results on a pro-
duction press.
3.19 mid-tone spread, S: Quantity defined by the
3.24 principal axis: The axis of a screen that co-
following equation:
incides with the direction of the longest diameter of
an oblong-shaped (e.g. elliptical or diamond-shaped)
S = max. [(A, - A& (A, - Am& (Av - AyoU -
half-tone dot.
- min. HA, - A&, (A, - Am()), (Av - +)I
NOTE 12 Circular and square-shaped half-tone dots do not
have a principal axis.
is the measured tone value of the cyan
AC
3.25 print substrate: Material bearing the printed
age.
proces s colour im
image.
A is the specified tone value of the cyan
co
process colour image. 3.26 printing forme: Tool whose surface is pre-
pared such that some parts transfer printing ink
is the measured tone value of the magenta
&l whereas other parts do not.
process colour image.
3.27 process colours (for four-colour printing):
is the specified tone value of the magenta
ArTlO
Yellow, magenta, cyan and black.
process colour image.
is the measured tone value of the yellow
AY 3.28 reference direction (of an image): Horizontal
process colour image.
direction as viewed by the end-user.
value of the yellow
is the s pecif ie d tone
AYO
3.29 reflectance factor, R: Ratio of the measured
process colour image.
reflected flux from the specimen to the measured
NOTE 10 Example for the calculation of the mid-tone reflected flux from a perfect-reflecting and perfect-
spread:
diffusing material located in place of the specimen.
[ISO 5-41 Unit: 1.
= (22, 17, 20)
measured values (c,m,y)
= (20, 20, 18)
specified values (c,m,y)
3.30 reflection density); reflectance factor den-
max. [(22-20) (I 7-20) (20-I 8)] =2
sity*). Logarithm to base ten of the reciprocal of the
reflectance factor. Unit: 1.
= -3
min. [(22-20), (17-20), (20-I 8)]
= (max. - min.) = 5
S
3.31 reflection densitometer: Instrument which
measures reflection density.
3.20 moire pattern: Unwanted periodic structure
produced by interference between two or more two-
3.32 reflectometer: Photometer for measuring
dimensional periodic structures.
quantities pertaining to reflection. [CIE 17.4, 845-05-261
3.21 OK print; OK sheet: During production print-
3.33 relative density: Density from which the den-
ing, the production print singled out as reference for
sity of a reference, such as the film base or the un-
the remaining production run.
printed print substrate, has been subtracted. Unit: 1.
3.22 off-press proof print: Print produced by a
3.34 sampling aperture size: Dimensions of the
method other than press printing whose purpose is to
surface area of a specimen that contributes to the
show the results of the colour separation process in a
measurement of the reflectance or transmittance factor
way that closely simulates the results on a production
density, governed by the design of the instrument.
press.
3.35 screen angle: For oblong-shaped half-tone dots,
NOTE 11 Also known as artificial or pre-press proof.
the angle which the principal axis of the screen makes
with the reference direction. For circular and square dot
shapes, the smallest angle which an axis of the screen
3.23 on-press proof print: Print produced by press
makes with the reference direction. Unit: Degree.
printing (production or proof press) whose purpose is
1) IS0 5-4.
2) CIE 17.4.
---------------------- Page: 7 ----------------------
0 IS0
IS0 12647=1:1996(E)
is the transmission density of the half-tone.
3.36 screen ruling; screen frequency: Number of
4
image elements, such as dots or lines, per unit of
length in the direction which produces the highest NOTE 17 Also known as the film printing dot area.
value. Unit: cm-l.
3.41 tone value; dot area (on a half-tone film of
3.37 screen width: Reciprocal of screen ruling.
negative polarity), A: Percentage calculated from the
Unit: urn.
formula:
3.38 surface finishing: Process by which a print is
A(%)=lOO-loo* l-lO-(Dt-Do)
either covered by varnish (lacquer) or laminated with a
I
transparent polymeric film.
where
3.39 tone value; dot area (on a print), A: Percent-
age of the surface which appears to be covered by is the transmission density of the clear
DO
colorant of a single colour (if light scattering in the half-tone film;
print substrate and other optical phenomena are
is the transmission density of the solid;
ignored), calculated from the formula:
4
is the transmission density of the half-tone.
I_ 1 o-(D,-DO) / I_ 1 o-(Ds-Do’ Dt
I[ 1
NOTE 18 Also known as the film printing dot area.
where
3.42 tone value increase; dot gain: Difference
is the reflection density of the unprinted
DO
between a tone value on the print and the correspond-
print substrate, or the non-printing parts of
ing tone value on the half-tone film. Unit: percent.
the printing forme;
NOTE 19 The synonym, dot gain, may be applied only to
is the reflection density of the solid;
D,
half-tones produced by dot patterns.
is the reflection density of the half-tone.
4
3.43 tone value sum: Sum of the tone values on all
colour separation films of a set. Unit: percent.
NOTES
13 Also known as apparent, equivalent or total dot area.
NOTES
14 The synonym, dot area, may be applied only to half-
20 Also known as the total dot area (TDA).
tones produced by dot patterns.
21 For most sets of colour separation films, the maximum
15 This definition may be used to provide an approxima-
of the tone value sum occurs at the position of the darkest
tion of the tone value on certain printing formes.
achromatic tone of the image.
16 In general it is assumed that the tone value [termed
“ink value” in IS0 126421 of the data is reproduced ident-
3.44 transmission densitometer: Device which
ically on the film produced by an image setter. Final films
measures transmission density.
should reproduce those tone values.
3.45 transmission density’); transmittance (op-
3.40 tone value; dot area (on a half-tone film of
tical) density % Logarithm to base ten of the recipro-
positive polarity), A: Percentage calculated from the
cal of the transmittance factor. Unit: 1.
formula:
3.46 transmittance factor,T: Ratio of the luminous
A (%) = loo* l-lO-‘Dt-DO) / l-l()-‘Ds-Do)
I [ 1
flux transmitted through an aperture covered by a
specimen to the luminous flux through the aperture
where
without the specimen in place. [ISO 5-21 Unit: 1.
is the transmissi
...
SLOVENSKI STANDARD
SIST ISO 12647-1:1997
01-marec-1997
*UDILþQDWHKQRORJLMD9RGHQMHSURFHVDL]GHODYHUDVWULUDQLKEDUYQLKL]YOHþNRY
SUHVNXVQLKLQSURL]YRGQLKRGWLVRYGHO 3DUDPHWULLQPHUVNHHQRWH
Graphic technology -- Process control for the manufacture of half-tone colour
separations, proof and production prints -- Part 1: Parameters and measurement
methods
Technologie graphique -- Maîtrise de procédé pour la fabrication des séparations de
couleur en ton tramé, des épreuves et des tirages en production -- Partie 1: Paramètres
et méthodes de mesure
Ta slovenski standard je istoveten z: ISO 12647-1:1996
ICS:
37.100.01 *UDILþQDWHKQRORJLMDQD Graphic technology in
VSORãQR general
SIST ISO 12647-1:1997 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 12647-1:1997
---------------------- Page: 2 ----------------------
SIST ISO 12647-1:1997
INTERNATIONAL IS0
12647-I
STANDARD
First edition
1996-I O-01
Graphic technology - Process control for
the manufacture of half-tone colour
separations, proof and production prints -
Part 1:
Parameters and measurement methods
Technologie graphique MaOrise de pro&d& pour la fabrication des
sbparations de couleur en ton tram& des gpreuves et des tirages en
production -
Partie 7: Paramktres et m&hodes de mesure
Reference number
IS0 12647-1: 1996(E)
---------------------- Page: 3 ----------------------
SIST ISO 12647-1:1997
IS0 12647=1:1996(E)
Foreword
a worldwide
IS0 (the International Organization for Standardization) is
federation of national standards bodies (IS0 member bodies) The work of
preparing International Standards is normally carried out ‘through IS0
technical committees. Each member body interested in a sub, ject for which
a technical committee has been established has the right to be rep-
resented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 12647-1 was prepared by Technical Committee
lSO/TC 130, Graphic technology.
IS0 12647 consists of the following parts, under the general title Graphic
technology - Process control for the manufacture of half-tone co/our
separations, proof and production prints:
Part 1: Parameters and measurement methods
- Part 2: Offset processes
Annex A forms an integral part of this part of IS0 12647. Annexes B and C
are for information only.
0 IS0 1996
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
II
---------------------- Page: 4 ----------------------
SIST ISO 12647-1:1997
@ IS0 IS0 12647=1:1996(E)
Introduction
When producing a half-tone colour reproduction it is important that the
colour separator, proofer and printer have previously specified a minimum
set of parameters that uniquely define the visual characteristics and other
technical properties of the planned print product. Such an agreement
enables the correct production of suitable separations (without recourse to
“trial-and-error”) and subsequent production of off-press or on-press proof
prints from these separations whose purpose is to simulate the visual
characteristics of the finished print product as closely as possible.
It is the purpose of this part of IS0 12647 to list and explain the minimum
set of process parameters required to uniquely define the visual character-
istics and related technical properties of a half-tone proof or production
print produced from a set of half-tone separation films. Other parts of IS0
12647 define specific values for these parameters which are appropriate
for specific processes (such as offset or gravure). For some processes
certain parameters are more significant than others and may be specified
as mandatory whilst the remainder are optional. However, in this part of
IS0 12647 all parameters are treated equally.
It is also necessary to distinguish between primary and secondary par-
ameters. This part of IS0 12647 describes only primary parameters.
Whereas primary parameters are defined as having a direct bearing on the
visual characteristics of the image, secondary parameters only influence
the image indirectly by changing the values of primary parameters. Secon-
dary parameters include
- colour separation film thickness;
- image orientation (wrong-reading or right-reading);
- film polarity (negative or positive);
- roughness of the emulsion surface;
- presence of colour marking or register marks.
Where necessary, for specific process applications, secondary parameters
may be specified in addition to primary parameters but they are not in-
cluded in this part of IS0 12647 except in the definitions.
During the process of colour separation for multi-colour half-tone printing, a
set of half-tone separation films is normally produced from a multi-coloured
continuous-tone original. This usually consists of a photographic trans-
parency or a reflection copy print though any graphic material, in analogue
or digital form, may be used.
The process of colour separation does not provide a unique transformation
of the colour values of the original into those of the production print. For
. . .
III
---------------------- Page: 5 ----------------------
SIST ISO 12647-1:1997
IS0 12647=1:1996(E) @ IS0
every distinguishable spot of the original, the colour (characterizable by
three calorimetric values, e.g. X, Y, Z or L*, a*, b* or hue, saturation and
lightness) has to be converted into tone values (dot areas) for four or more
process colour separation films. However, in most cases the density range
(and, hence, colour gamut) of the original is wider than that achievable in
press printing. As a result, the colour separation process requires some
degree of interpretation of the original by the colour separator and the
resultant transformation may differ from one original to another.
Whatever freedom there exists for the colour separation process, it is
important that the values of the process parameters of the printing press
to be used for production are taken into account. This is because the
process steps that follow colour separation, namely proofing (on- and off-
press), production of the printing forme (for on-press proofing or pro-
duction printing), production printing and print surface finishing, are
normally carried out with a rigid set of process parameters which include
- the properties of the print substrate;
- the optical properties of solid prints of the process inks;
- the tone value increase curve.
Maintaining consistent values for the parameters at all steps in the process
is important to ensure predictable reproduction. Any unforeseen variation
of these values is usually to the detriment of the visual characteristics of
the image.
The technical background discussed so far shows that the processes of
colour separation and proofing require prior knowledge of the values of the
process parameters encountered in production printing. Since it is virtually
impossible to print all jobs with the same set of process parameters,
irrespective of the type of press, printing forme, or substrate used, there
has to be an efficient information exchange between the colour separator,
the proof printer and the production printer which defines the specific
parameters for that job.
To facilitate the information interchange, this part of IS0 12647 defines a
number of parameters whose values should be specified when a set of
colour separation films, with accompanying proof print, is being ordered.
Specific values for each parameter are assigned in other parts of
IS0 12647; this part is concerned with definitions and test methods only.
Because the proof print is the principal means of communication between
pre-press and printing, it is important that
- the proof print be made using the best achievable simulation of the
intended printing parameters and
- productio n prin ting attem pt to match the visual characteristics of the
approved proof print.
One of the major variations between and within printing processes is
between tone value increase curves (or “dot gain curves”), examples of
which are shown schematically in figure 1. One such curve, with appro-
priate tolerances, may be specified for every process colour for each
specific combination of substrate and printing process.
iv
---------------------- Page: 6 ----------------------
SIST ISO 12647-1:1997
IS0 12647=1:1996(E)
INTERNATIONAL STANDARD @ IS0
Graphic technology - Process control for the manufacture of
half-tone colour separations, proof and production prints -
Part 1:
Parameters and measurement methods
- coldset offset and letterpress proof and pro-
1 Scope
duction printing and off-press proof printing on
newsprint;
IS0 12647 specifies parameters which define printing
conditions for the various processes used in the
- gravure printing;
graphic arts industry. The values of the parameters
specified may be used in the exchange of data to
- screen printing;
characterize the intended printing condition and/or for
- flex0 printing.
the process control of printing by practitioners wishing
to work to common goals.
2 Normative references
This part of IS0 12647
The following standards contain provisions which,
through reference in this text, constitute provisions of
- defines vocabulary and establishes a minimum set
this part of IS0 12647. At the time of publication, the
of process parameters that uniquely determine a
printed four-colour half-tone image. (These apply editions indicated were valid. All standards are subject
to revision, and parties to agreements based on this
to others parts of IS0 12647 as well.) The par-
part of IS0 12647 are encouraged to investigate the
ameters were selected in view of the process
possibility of applying the most recent editions of the
stages “colour separation”, “making of the print-
“production printing” and standards indicated below. Members of IEC and IS0
ing forme”, “proofing”,
maintain registers of currently valid International
“surface finishing” being directly applicable to
proofing and printing processes that use colour Standards.
separation films as input;
IS0 5-2: 1991, Photography - Density measurements
- is directly applicable to proofing and printing from - Part 2: Geometric conditions for transmission
printing surfaces produced by filmless methods density.
and to gravure printing as long as direct analogies
IS0 5-3: 1995, Photography - Density measurements
to film production systems are maintained;
- Part 3: Spectral conditions.
- is applicable to printing with more than four pro-
IS0 5-4: 1995, Photography - Density measurements
cess colours as long as direct analogies to four-
- Part 4: Geometric conditions for reflection density.
colour printing are maintained;
- is applicable to line screens and, where relevant, IS0 13655:1996, Graphic technology - Spectral
to those that do not have regular screen angles or measurement and calorimetric computation for
regular screen rulings. graphic arts images.
CIE 17.4 (1987), International lighting vocabulary.
Other parts of IS0 12647 cover specifications for
individual printing processes or groups of these, such
as
3 Definitions
- four-colour proof and production printing on heat-
For the purposes of IS0 12647, the following defi-
set web, sheet-fed and continuous forms offset
nitions apply.
presses, offset proofing for half-tone gravure;
---------------------- Page: 7 ----------------------
SIST ISO 12647-1:1997
IS0 12647=1:1996(E) @ IS0
NOTE 1 For quantities, the preferred unit is given together 3.9 control strip: One-dimensional array of control
with the definition. By definition, the unit of so-called
patches.
dimensionless quantities is 1.
3.10 core density (on a half-tone film): Transmit-
3.1 achromatic (perceived) colour: Colour devoid
tance density in the centre of an isolated opaque
of hue, in the perceptual sense. [CIE 17.4, 845-02-261
image element such as a half-tone dot or line. Unit: 1.
NOTES
3.11 deviation tolerance: Permissible difference
2 The colour names white, grey and black are commonly
between the OK print from a production run and the
used or, for transmitting objects, colourless and neutral.
reference value.
3 In printing practice, achromatic colours can be produced
either by a single ink or three chromatic inks suitably
3.12 film emulsion orientation: Orientation of a
balanced.
colour separation film relative to the observer with
respect to the emulsion side.
3.2 axis of a screen: One of the two directions in
which the half-tone pattern shows the highest num-
NOTE 7 Normal orientation is emulsion up, i.e. towards
ber of image elements, such as dots or lines, per unit
the observer.
of length.
3.13 film polarity: Positive if clear and solid areas
3.3 chromatic (perceived) colour: Perceived colour
on the film correspond to unprinted and solid areas on
possessing hue, in the perceptual sense. [CIE 17.4,
the print, respectively. Negative if clear and solid
845-02-271
areas on the film correspond to solid and unprinted
areas on the print, respectively.
NOTE 4 The process inks cyan, magenta and yellow are
the chromatic colour inks.
3.14 fringe width (of an isolated opaque image
3.4 CIELAB colour difference; CIE 1976 I,*, a*, b* element): Average distance between the density
colour difference AE&: Difference between two contour lines corresponding to 10 % and 90 % of the
minimum core density specified for the printing pro-
colour stimuli defined as the Euclidean distance
cess under consideration. Unit: urn.
between the points representing them in L*, a*, b*
space. [CIE 17.4, 845-03-551 Unit: 1.
3.15 grey balance: Set of tone values for cyan,
3.5 CIELAB colour space; CIE 1976 L*, a*, b* magenta and yellow on the colour separation films is
colour space: Three-dimensional, approximately uni-
in grey balance if a print produced under specified
form colour space produced by plotting IL*, a*, b* in
printing conditions appears as an achromatic colour
rectangular coordinates. [CIE 17.4, 845-03-561
under specified viewing conditions.
3.6 calorimeter: Instrument for measuring color-
3.16 half-tone film: Film for use with a half-tone
imetric quantities, such as the tristimulus values of a
printing process showing image elements like dots or
colour stimulus. [CIE 17.4, 845-05-I 81
lines.
NOTE 5 A photoelectric calorimeter achieves this by the
analogue integration of the spectral product of object
3.17 hard dot film: Colour separation film with half-
reflectance or transmittance factor, illuminant and filters
tone dots that reproduce reliably in film duplication
which are defined by standard illuminant and the standard
and production of the printing forme.
observer functions. A spectrophotometric calorimeter
achieves this by calculation from the spectral data.
3.18 image orientation: Images are referred to as
right-reading (opposite: wrong-reading) if text appears
3.7 colour separation film: One of a set of black-
as it is intended to be read and images are in the
and-white half-tone films for process printing that
orientation intended for viewing by the end-user.
pertains to one process colour.
NOTES
NOTE 6 There are usually four colour separation films in a
set.
8 The film emulsion orientation requires specification as
well: “emulsion up”, or “emulsion down” is stated.
3.8 control patch: Area produced for control or “Emulsion up” is usually assumed if there is no film emul-
sion orientation statement.
measurement purposes.
2
---------------------- Page: 8 ----------------------
SIST ISO 12647-1:1997
IS0 12647=1:1996(E)
@ IS0
9 A typical reference is “wrong-reading emulsion up” to show the results of the colour separation process
which is equ ivalent to ” righ t-reading emulsion down”.
in a way that closely simulates the results on a pro-
duction press.
3.19 mid-tone spread, S: Quantity defined by the
3.24 principal axis: The axis of a screen that co-
following equation:
incides with the direction of the longest diameter of
an oblong-shaped (e.g. elliptical or diamond-shaped)
S = max. [(A, - A& (A, - Am& (Av - AyoU -
half-tone dot.
- min. HA, - A&, (A, - Am()), (Av - +)I
NOTE 12 Circular and square-shaped half-tone dots do not
have a principal axis.
is the measured tone value of the cyan
AC
3.25 print substrate: Material bearing the printed
age.
proces s colour im
image.
A is the specified tone value of the cyan
co
process colour image. 3.26 printing forme: Tool whose surface is pre-
pared such that some parts transfer printing ink
is the measured tone value of the magenta
&l whereas other parts do not.
process colour image.
3.27 process colours (for four-colour printing):
is the specified tone value of the magenta
ArTlO
Yellow, magenta, cyan and black.
process colour image.
is the measured tone value of the yellow
AY 3.28 reference direction (of an image): Horizontal
process colour image.
direction as viewed by the end-user.
value of the yellow
is the s pecif ie d tone
AYO
3.29 reflectance factor, R: Ratio of the measured
process colour image.
reflected flux from the specimen to the measured
NOTE 10 Example for the calculation of the mid-tone reflected flux from a perfect-reflecting and perfect-
spread:
diffusing material located in place of the specimen.
[ISO 5-41 Unit: 1.
= (22, 17, 20)
measured values (c,m,y)
= (20, 20, 18)
specified values (c,m,y)
3.30 reflection density); reflectance factor den-
max. [(22-20) (I 7-20) (20-I 8)] =2
sity*). Logarithm to base ten of the reciprocal of the
reflectance factor. Unit: 1.
= -3
min. [(22-20), (17-20), (20-I 8)]
= (max. - min.) = 5
S
3.31 reflection densitometer: Instrument which
measures reflection density.
3.20 moire pattern: Unwanted periodic structure
produced by interference between two or more two-
3.32 reflectometer: Photometer for measuring
dimensional periodic structures.
quantities pertaining to reflection. [CIE 17.4, 845-05-261
3.21 OK print; OK sheet: During production print-
3.33 relative density: Density from which the den-
ing, the production print singled out as reference for
sity of a reference, such as the film base or the un-
the remaining production run.
printed print substrate, has been subtracted. Unit: 1.
3.22 off-press proof print: Print produced by a
3.34 sampling aperture size: Dimensions of the
method other than press printing whose purpose is to
surface area of a specimen that contributes to the
show the results of the colour separation process in a
measurement of the reflectance or transmittance factor
way that closely simulates the results on a production
density, governed by the design of the instrument.
press.
3.35 screen angle: For oblong-shaped half-tone dots,
NOTE 11 Also known as artificial or pre-press proof.
the angle which the principal axis of the screen makes
with the reference direction. For circular and square dot
shapes, the smallest angle which an axis of the screen
3.23 on-press proof print: Print produced by press
makes with the reference direction. Unit: Degree.
printing (production or proof press) whose purpose is
1) IS0 5-4.
2) CIE 17.4.
---------------------- Page: 9 ----------------------
SIST ISO 12647-1:1997
0 IS0
IS0 12647=1:1996(E)
is the transmission density of the half-tone.
3.36 screen ruling; screen frequency: Number of
4
image elements, such as dots or lines, per unit of
length in the direction which produces the highest NOTE 17 Also known as the film printing dot area.
value. Unit: cm-l.
3.41 tone value; dot area (on a half-tone film of
3.37 screen width: Reciprocal of screen ruling.
negative polarity), A: Percentage calculated from the
Unit: urn.
formula:
3.38 surface finishing: Process by which a print is
A(%)=lOO-loo* l-lO-(Dt-Do)
either covered by varnish (lacquer) or laminated with a
I
transparent polymeric film.
where
3.39 tone value; dot area (on a print), A: Percent-
age of the surface which appears to be covered by is the transmission density of the clear
DO
colorant of a single colour (if light scattering in the half-tone film;
print substrate and other optical phenomena are
is the transmission density of the solid;
ignored), calculated from the formula:
4
is the transmission density of the half-tone.
I_ 1 o-(D,-DO) / I_ 1 o-(Ds-Do’ Dt
I[ 1
NOTE 18 Also known as the film printing dot area.
where
3.42 tone value increase; dot gain: Difference
is the reflection density of the unprinted
DO
between a tone value on the print and the correspond-
print substrate, or the non-printing parts of
ing tone value on the half-tone film. Unit: percent.
the printing forme;
NOTE 19 The synonym, dot gain, may be applied only to
is the reflection density of the solid;
D,
half-tones produced by dot patterns.
is the reflection density of the half-tone.
4
3.43 tone value sum: Sum of the tone values on all
colour separation films of a set. Unit: percent.
NOTES
13 Also known as apparent, equivalent or total dot area.
NOTES
14 The synonym, dot area, may be applied only to half-
20 Also known as the total dot area (TDA).
tones produced by dot patterns.
21 For most sets of colour separation films, the maximum
15 This definition may be used to provide an approxima-
of the tone value sum occurs at the position of the darkest
tion of the tone value on certain printing formes.
achromatic tone of the image.
16 In general it is assumed that the tone value [termed
“ink value” in IS0 1264
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.