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Paper presented at 22nd Color Imaging Conference, Boston, MA, November 7th, 2014. Review of the EU funded CP7.0 project
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Colour Printing 7.0
Next Generation Multi-Channel Printing
Ludovic G. Coppel, Aditya Sole, Jon-Yngve Hardeberg
22nd Color Imaging Conference, BostonNovember 7th 2014Workshop on Next Generation Colour Printing
2
Multichannel / Spectral Printing
Multilayer Printing
Colour Printing 7.0
3
Next Generation Multi-Channel Printing
EU Marie Skłodowska-Curie ITN 2012 – 2015
Train a new generation of printing scientists
Research focused on multichannel and multilayer printing
7 Phd students, 2 postdocs
The project
11/11/2014 4
Spectral reproduction workflow and multi-channel printers
Halftoning for multi-channel printers
Spectral printer models, paper-ink interaction
2.5D printing, multilayering, gloss control and fine art applications
6
Spectral printing
7
Good spectral match colorimetric match under various viewing conditions
Spectral proofing
8
Slavuj, Marijanovic, Hardeberg, “Colour and spectralsimulation of textile samples onto paper: a feasibility study,” . J. AIC 12 (2014).
Coppel, Le Moan et al., “Next generation printing - towards spectral proofing,” IARIGAI 2014.
Paramer mismatch spectral gamut mapping
Urban P. and Berns R. S. (2011), “Paramer Mismatch-Based Spectral
Gamut Mapping,” IEEE Transactions on Image Processing 20(6), 1599-
1610.
Determine all metamers in e.g. D50
Select those that are metamers in e.g. A
…
CMYKRGB space
CMYK
10400 450 500 550 600 650 700
0
0.2
0.4
0.6
Wavelength (nm)
R
C10M47Y51K28
C23M52Y56K7
Munsell 5R 6/6
E = 0.5E = 0.7metamers
E = 2.8E = 4.0 not metamers
CMYKRGB
11
400 450 500 550 600 650 7000
0.2
0.4
0.6
Wavelength (nm)
R
Munsell 5R 6/6
Y23K52R56B7
E = 0.6
E = 0.5
Results: colorimetric (D50)
11/11/2014 12
ΔE2000 < 1
(%)
1 < ΔE2000 < 3
(%)
ΔE2000 > 3
(%)
CMYK 95 4 1
CMYKRGB 99 1 0
RGB channels increase the colorimetric gamut (D50)
Results: multi-illuminants
11/11/2014 13
mean
ΔE
max
ΔE
DE ≤ 1
%
DE ≤ 3
%
DE > 6
%
A CMYK col
CMYK spec
CMYKRGB
4.7
2.4
0.5
8
3.9
2.2
0
0
85
10
82
15
15
0
0
F11 CMYK col
CMYK spec
CMYKRGB
3.7
1.9
1.7
8.6
5.9
5.9
4
22
32
38
60
54
15
0
0
Spectral prints: MetaCow
14
Banding artefacts
15Samadzadegan Urban, “Spatially resolved joint spectralgamut mapping and separation,” IS&T CIC (2013).
Spatially Resolved Joint Spectral Gamut Mapping and Separation
Smoother spectral separation
Preserve image edges
Model calibration
16
CMYK, CMYR, CMRG, etc….
35 x 54 = 21875 calibration patches for 4-cells cellular YN modified Neugebauer model!
Model depends on:
Inks Printer Substrate Halftoning
…and needs calibration
CMYKRGB
Needs better (modular) models requiring less calibration.
Spectral colour prediction models
18
Coppel, “Dot gain analysis from probabilistic spectral modelling of colour halftone,” IARIGAI (2014).
Need physical model to separate mechanical from optical dot gain Probabilistic modelling rather than Yule-Nielsen
Model fluorescence
R()
Microscale imaging
19
Namedanian, Nyström, et al., “Physical and optical dot gain: characterization and relation to dot shape and paper properties,” SPIE EI Vol. 9015 (2014).
Rahaman, Norberg, Edström, “Microscalehalftone color image analysis: perspective of spectral color prediction modeling,” SPIE EI Vol. 9015 (2014).
coated uncoated
Multi-pass prints
21Olen, Padfield, Parraman, “Reproducing the old masters: applying colour mixing and painting methodologies to inkjet printing,” SPIE EI Vol. 9015 (2014).
Maximise colour saturation
Special effects (bronzing)
Subtle colour variations in darker regions
Thomas Gainsborough, Isabella (1769)
Multi-pass prints
22
Colour depends on the printing order
Olen, Parraman, “Exploration of alternative print methodology for colour printing through the multi-layering of ink,” AIC (2013).
2.5D prints (lenticular)
23
Ghosting reduction
24
T. Baar,M. Shahpaski, andM. V. Ortiz Segovia, “Image ghosting reduction in lenticular relief prints,” in Proc. SPIE Vol. 9018 (2014).
Compensates for cross-talk (ghosting) making parts of one image remaining visible in the viewing direction corresponding to the other image.
Printing gloss effects
25T. Baar, S. Samadzadegan, H. Brettel, P. Urban, and M. V. OrtizSegovia, “Printing gloss effects in a 2.5D system,” in “Proc. SPIEVol. 9018,” (2014), pp. 90180M–90180M–8
Gloss control
26
Standard prints: gloss increases with ink coverage.2.5 D printing allows printing nearly constant gloss value independently of ink coverage.
Print on white layer increases gloss
Multi-pass printing increases roughness
Gloss can be controlled by time between white layers
Time dependent gloss
27
Measured gloss as a function of
time delay between two white
layers in WWCMY print mode.
Multiple ICC profiles
28
T. Baar and M. Segovia, “Colour management of prints with variantgloss,” in IS&T 22nd Color and Imaging Conference (2014).
Assessing Quality
29
How to evaluate the outcome of 2.5D prints?
What about spectral images?
Gloss perception
Baar, Brettel, Segovia, “A survey of 3d image qualitymetrics for relief print evaluation Metrics” CVCS Gjøvik (2013).
Spectral image difference
31
original repro Lightness structure difference
Hue difference map
Le Moan, Urban, “Image-difference prediction: From colorto spectral,” IEEE Transactions on Image Processing (2014).
Spectral Profile Connection Space
32Le Moan, Urban, “A new connection space for low dimensional spectral color management”, SPIE Electronic imaging Vol. 9018 (2014).
Conclusions
33
Multi-channel and multi-layering (2.5D/3D) printing open new research areas and applications in printing.
CP7.0 outcomes:o Significant contributions to spectral printing workflowo Deeper understanding of light-paper-ink interactiono 2.5D printingo Method for controlling glosso Fine art reproductiono Framework for spectral image quality assessment and
communication of spectral images
CP7.0 outlook
34
What future for printing spectral?
How many colour channels do we need?
Reproducing material appearance
What market?