PIA Color Management Conference, 2011
Internet
Tablet PC
Printing the
Expected
DVD, Motion
Picture
„Multi Channel Publishing“
Consistent colour rendering
across all media
Printing
¬ Typical colour gamuts
¬ Representing the range of output media
¬ Act as an interchange or exchange space
The IGF research project Fogra No. 35.003 of the Fogra Graphic
Technology Research Association, Streitfeldstrasse 19, 81673
Munich, was funded by the AiF under the program for promoting
industrial research and development(IGF) of the Federal Ministry of
Economics and Technology, based on a resolution of the German
Bundestag.
Conventional Printing
Andreas Kraushaar | [email protected]
Digital Printing
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PIA Color Management Conference, 2011
Agenda
1. Who and what is Fogra?
2. How about customer expectations?
3. Image appraisal types (for digital printing)
4. From ISO 12647-2
ISO 15311
5. The challenges for image quality assessment
6. Image quality attributes in details
7. Where do we go?
Andreas Kraushaar | [email protected]
2
PIA Color Management Conference, 2011
1. The industry needs independent research
¬ In 1951 the german printing industry (small and medium enterprises)
decided to put some money together
¬ Fogra stands for “Forschung im grafischen Gewerbe” - research in the
graphic arts
¬ Fogra is “governed/owned” by its members (who also constitute the
board of directors)
neutrality
¬ Aiming for an “lawyer of the printer” - an manufacturer independent
organization
¬ Similar organizations in US (GATF), UK (PIRA), Switzerland (Ugra),
Spain (AIDO), etc
¬ Fogra is financed (ca. 5 Million € turnover) by
¬
¬
¬
1 Mio. membership fees
2 Mio. research funds from the country/state/EU (based on extensive application)
In order to compensate for the remaining losses, Fogra provides regular services
such as control wedges, certifications, symposia etc
Andreas Kraushaar | [email protected]
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PIA Color Management Conference, 2011
1. Fogra - the service provider in the
graphic arts industry
Cons
ultanc
expery, measurin
t opin
ions g and
rch
Resead
An
t
pmen
develo
FograServices
Comm
ittee w
ork
Stand and
ardiza
tion
ion
minat
Disse and
g
Trainin
Fogra, active in four fields of activities
Andreas Kraushaar | [email protected]
4
PIA Color Management Conference, 2011
2. What are the customer's expectations?
Internet
Tablet PC
DVD, Motion
Picture
„Multi Channel Publishing“
Consistent colour rendering
across all media
Lets ask PDF/X
ISO 15930-7: to permit the
predictable dissemination of a
compound entity to one or more
locations.
Printing
¬ Typical colour gamuts
¬ Representing the range of output media
¬ Act as an interchange or exchange space
Andreas Kraushaar | [email protected]
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PIA Color Management Conference, 2011
2. Zero and Full reference
Full Reference
¬ Consistency
¬ Predictability
¬ Closer is better
Do we need to have the same
level of accuracy (tolerances)?
Certainly not.
Accuracy
Are there more expectations?
Sure!
Zero Reference
ISO 15311 proposal:
Quality types A, B & C
¬ Make it "Sexy"
Match Preferences
Andreas Kraushaar | [email protected]
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PIA Color Management Conference, 2011
3. Digital Printing - Types of image appraisal
Being able to reproduce the same
colour to replace a part or reprint
after a while
Being able to print without visible
banding (uniform). Resolution is
depending on distance and size
achieving the same colour
on totally different substrates
Andreas Kraushaar | [email protected]
Source: R. Blind
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PIA Color Management Conference, 2011
5. ISO 15311 provides 3 levels of predictability
Identical
colours
¬ Proofing [ISO 12647-7]
¬ Validation Print [-8]
¬ PSO ISO 12647-2
¬ PSD ISO 15311-x
Side-by-Side
media-relative
colours
consistent
colours
¬ PSD ISO 15311-x
¬ small gamut-difference
between ref. and print
Comparison w. memory
¬ PSD ISO 15311-x
¬ “Common
¬
Appearance”
big gamut differences
Side-by-Side
Predictability of the final colour - upfront
Full Colour Ref - Absolute
Full Colour Ref - Media Relative
Andreas Kraushaar | [email protected]
Partial Colour Ref.
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PIA Color Management Conference, 2011
4. From ISO 12647-2 to ISO 15311-1
Digital
Offset
Machine
Machine
wet in
wet
different
technologies
Ink
Paper
Complex but mostly known
behavior of components and their
interplay separable
standardizeable
Substrates
Ink
Highly integrated systems. Hardly
separable
Define Combinations
Define expected outcome
Andreas Kraushaar | [email protected]
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PIA Color Management Conference, 2011
4. ISO 15311-1: The toolbox for image quality
Graphic technology - Requirements for printed matter utilizing digital
printing technologies for the commercial and industrial production Part 1: Parameters and measurement methods
Scope
This part of ISO 15311 defines print quality attributes and
measurement methods for digital prints. These parameters
provide a basis to allow subsequent parts of this International
Standard to define acceptable conformance criteria for
particular use cases.
Andreas Kraushaar | [email protected]
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PIA Color Management Conference, 2011
4. Laboratory and Practical criteria
4.3.2
4.3.2.1
4.3.2.2
4.3.2.3
4.3.2.4
4.3.2.5
Colour and surface finish
Requirements of unprinted substrate
colour accuracy requirements
Consistent reproduction of tone values
Ink Set Gloss
Further criteria
4.3.3
4.3.3.1
4.3.3.2
4.3.3.3
4.3.3.4
4.3.3.5
4.3.3.6
Homogeneity
Streakiness
Background Haze
Graininess and Mottle
Fill (caries)
Inking variation across the format and within the printing direction
Further criteria
4.3.4
4.3.4.1
4.3.4.2
4.3.4.3
4.3.4.4
4.3.4.5
4.3.4.6
4.3.4.7
4.3.4.8
4.3.4.9
Resolution
Line Width
Native Addressability
Effective addressability
Raggedness
Blurriness
MTF (Modulation transfer function)
Register
Patterning
Further requirements
4.3.5
4.3.5.1
4.3.5.2
4.3.5.3
"System Check"
"Print Check"
?
?
?
?
?
?
?
?
Artefacts
Contouring
Spreading (misdirected dots, satellites)
Use case specific criteria
Andreas Kraushaar | [email protected]
dedicated criteria for
systems & printer
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PIA Color Management Conference, 2011
4. Potential implementation
Consistent colour rendering
across all media
Conven9onal Prin9ng
Digital Produc9on
ISO 12647
ISO 15311
-7
-8
Contract
Proof
Valida9on
Print
-1
-2/3
Offsetprint
Andreas Kraushaar | [email protected]
-2
Concept, Toolbox
Lite Produc9on
-3
....
LFP
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PIA Color Management Conference, 2011
5. Challenges for image quality assessment
„When you can measure what you are speaking
about and express it in numbers, you know
something about it“
Lord W. T. Kelvin, Lecture to the Institution of Civil
engineers, London, 3 May 1883
"All colors must be evaluated numerically".
A. Kling, Keynote, Color Management Conference
We need objective measures
(if possible based on agreed upon standards)
„The ultimate test of any colour reproduction is the
opinion of the person who views it. But opinions differ...“
R. W. G. Hunt. In: The reproduction of color
We need to focus on use cases which provides
(full) reference (contrary to no reference)
Andreas Kraushaar | [email protected]
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PIA Color Management Conference, 2011
5. How is print image quality define so far?
ISO 12647-7/8
1,2,3 - Scope, normative references, terms & definitions
4 - requirements
5 - Test methods
4.1 data
data
halftone
4.2 digital print
substrates
coloration
rub resistance
ink set gloss
reproduction limits
tone value repro
vignettes
resolving power
margin info
gamut
5.1 control strip
5.2 test objects, measurements, visual
Annexes [A: metal slab | B: Certification]
Andreas Kraushaar | [email protected]
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PIA Color Management Conference, 2011
5. Categorization of image quality attributes
System
Colour
reproduction
Resolution
Permanence
Uniformity
Artefacts
Functional
performance
¬ Productivity
¬ on site reliability
¬ etc.
Health, Safety,
Environment
arbitrary but useful
Andreas Kraushaar | [email protected]
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PIA Color Management Conference, 2011
6. Image quality attributes in details
concept: Individual attributes contribute to a recognized overall
image quality. (compare the rating of food)
Quality Type A
Quality Type B
Quality Type C
Colour
Homogeneity
Perceptual Resolution
Andreas Kraushaar | [email protected]
Artefacts
1
2
3
4
5
6
...
+ individual
needs
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PIA Color Management Conference, 2011
6.1 Evaluation of the colour reproduction
¬ Providing tolerances for the three quality types
¬ Providing tolerances for spot colour reproduction
¬ based an selected image appraisal types
(identical versus media-relative)
¬ Common appearance to be added later
Andreas Kraushaar | [email protected]
current candidate of ISO 15311-2
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PIA Color Management Conference, 2011
6.1 Colour: Number of visual & technical discernible
tonal steps
Andreas Kraushaar | [email protected]
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PIA Color Management Conference, 2011
6.2 Perceptual resolution - concept
Testchart-Design
Perceptual
Resolution Correlate
Correct Interpretation
(Driving) - “RIP-resolution”
Resolution attributes
¬
¬
¬
¬
¬
¬
Printing
- “Imaging-resolution”
Print Inspection
(visually | measurement
wise)
native addressability
effective addressability
edge blurriness
edge raggedness
MTF
more to come
Andreas Kraushaar | [email protected]
19
PIA Color Management Conference, 2011
6.2 Perceptual resolution
¬ Different tolerances for the pertinent quality levels
¬ edge blurriness and edge raggedness
¬ legibility
¬ Mis-registration
ISO 15311-2 candidate
Andreas Kraushaar | [email protected]
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PIA Color Management Conference, 2011
6.2 Correlates tested so far at Fogra
• Edge Sharpness (inverse of blurriness)
– a measure of the average edge profile transition width in the direction
perpendicular to the edge
– using the square
• Edge Raggedness
– a measure of the average edge profile variation (50%) in the direction parallel to
the edge
– using the rotated squares with 8 degree
JTC1, SC28 WG4 works actively on these measures
¬ Further fine tuning is needed
¬ Round robin tests are underway
¬ Practical aspects of scanner influence, repeatability and
reproducibility are yet to be evaluated
1
2
3
4
5
Andreas Kraushaar | [email protected]
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PIA Color Management Conference, 2011
6.2 blurriness and raggedness in detail
Raggedness
Blurriness
Scan
Andreas Kraushaar | [email protected]
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PIA Color Management Conference, 2011
6.2 Mis-Registration (example)
¬ Digital production machine
¬ Print Run: 500
¬ Data Path: Device Mode
¬ Test elements: 4 Positions
¬ Format: SRA3
2000 measurements for K/C, K/C, K/Y
Pos. 3
Pos. 4
printing
direction
Pos. 1
A
Pos. 2
B
C
Andreas Kraushaar | [email protected]
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PIA Color Management Conference, 2011
6.3 Evaluation of homogeneity
Homogeneity (uniformity)
subjective impression of colour uniformity across
a large image that is intended to have a uniform colour.
Refers to all types of colour variation:
¬ lightness, hue, saturation
¬ derivatives of these can be measured separately or in combination
Variation geometry:
¬ 1D, 2D, periodic, aperiodic, localized, large-scale, and small-scale
variation, separately or in combination such as streaks, bands, gradients,
mottle, graininess and moiré.
Andreas Kraushaar | [email protected]
24
PIA Color Management Conference, 2011
6.3 Evaluation of homogeneity
Development of M-Score:
1. Compute the CIELAB
colour differences ∆E00
between neighbouring patches
2. Sum measurements for
rows and columns and
normalize them.
0 .. 100
3. Calculate M-Score
Andreas Kraushaar | [email protected]
25
PIA Color Management Conference, 2011
6.3 M-Score in detail
M-Score
Meaning
Comments
≥ 95
Perfect
Inkjetprint on proofing substrate showing no
visible inhomogeneities
> 80
Very Good
Print with slightly visible inhomogeneities (e.g.
some Mottling). No visible stripes.
> 70
Good
Print with visible inhomogeneities (Mottling) but
almost no visible stripes.
> 60
Satisfactory
Mottling and stripes visible. Is still accepted by
most observers.
> 50
Adequate
Print with clearly visible mottling and/or stripes.
Acceptance is highly dependent on the printed
image.
< 50
Poor (But
sellable)
Clearly visible mottling and stripes. Not accepted
as high quality print
Andreas Kraushaar | [email protected]
26
PIA Color Management Conference, 2011
6.3 How to use M-Score in a standard ….
ISO 15311-2 candidate
toner based systems
based on a evaluation of photo books
(toner based systems)
Andreas Kraushaar | [email protected]
27
PIA Color Management Conference, 2011
6.3. Homogeneity: Next steps
¬ M-Score works good for toner based systems (i.e. it correlates well
with absolute (magnitude estimation) and relative scales (rank
order))
¬ It ought to be tested how much similar metrics such as ISO 13660
(replacement: ISO 24790) mottle improve the performance
¬ It will be evaluated also for inkjet prints
¬ Streaks will be evaluated by the “Offset method”
Andreas Kraushaar | [email protected]
28
PIA Color Management Conference, 2011
6.3. Homogeneity: One word about graininess
Rank order experiment
test charts
different levels of graininess
¬ We propose three default
¬
viewing distances (50 cm
[reading], 100 cm [POP] and
1,5 m [Large Format]
Simple evaluation of standard
test chart with a standard
scanner
Andreas Kraushaar | [email protected]
29
PIA Color Management Conference, 2011
Why did I leave out ISO 15339?
Internet
Tablet PC
DVD, Motion
Picture
„Multi Channel Publishing“
Consistent colour rendering
across all media
Printing
¬ Typical colour gamuts
¬ Representing the range of output media
¬ Act as an interchange or exchange space
ISO 12647-x
ISO 15339
ISO 15311-x
Andreas Kraushaar | [email protected]
30
PIA Color Management Conference, 2011
Summa
¬ Think about customers expectation
¬ ISO 15311 defines new (old) things:
¬ Different levels of quality types (currently A, B & C)
¬ Different ways of image appraisal
(Sidy-by-Side and media relative)
¬ Framework for common appearance (to be added if
understood objectively)
¬ Defining capabilities of combination rather than
individual components
¬ A collection of important image quality attributes has
been collected and is under testing
¬ Setup your workflow accordingly to print the expected
Andreas Kraushaar | [email protected]
31
PIA Color Management Conference, 2011
7. Together we can do it
“The best person to decide what research work shall be
done is the man who is doing the research.
The next best is the head of the department.
After that you have the field of best persons and meet
increasingly worse groups.
The first of these is the research director, who is
probably wrong more than half the time.
Then comes a committee, which is wrong most of the time.
Finally there is the committee of company vice-presidents,
which is wrong all the time.“
Dr. C. E. K. Mees
(Kodak)
Andreas Kraushaar | [email protected]
32
PIA Color Management Conference, 2011
8. If you are close to germany, come by
drupa 2012
You got compared anyhow.
Here you know the rules
and the referee!
Andreas Kraushaar | [email protected]
33
PIA Color Management Conference, 2011
Brand-new
Fogra PSD
Andreas Kraushaar | [email protected]
Backup
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PIA Color Management Conference, 2011
8. The PSD-concept: An overview
1. Output process control
prepress
2. Colour Fidelity
✔
large format
✔
✔
small format
Match
Consistency
3. Workflow
✔ Preflight
✔ PDF/X-Output
✔ Profile-handling
✔ PDF/X-Creation
✔ Altona Test Suite V1 & V2
✔ Light-Audit
Andreas Kraushaar | [email protected]
35
PIA Color Management Conference, 2011
Common appearance in a nutshell
reference
actual print
RGB
CMYK1
CMYK2
e.g. ECIV2
e.g.
FOGRA39
Separation
RGB
Proof to
Print Match
CMYK1
e.g. IFRA26
e.g. ECIV2
Separation
Andreas Kraushaar | [email protected]
ISO 12647-2
PT 1/2
CMYK2
Proof to
Print Match
ISO
12647-3
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PIA Color Management Conference, 2011
4.Printing can also be done a little different
You can print “nicely” with it and you might achieve similar/identical results
But it is not spot on on ISO 12647-2 TVI aims
Creative work
Andreas Kraushaar | [email protected]
37