miun.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Whiteness and Fluorescence in Paper: Perception and Optical Modelling
Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics. (DPC)
2010 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is about modelling and predicting the perceived whiteness of plain paper from the paper composition, including fluorescent whitening agents. This includes psycho-physical modelling of perceived whiteness from measurable light reflectance properties, and physical modelling of light scattering and fluorescence from the paper composition.

Existing models are first tested and improvements are suggested and evaluated. The standardised and widely used CIE whiteness equation is first tested on commercial office papers with visual evaluations by different panels of observers, and improved models are validated. Simultaneous contrast effects, known to affect the appearance of coloured surfaces depending on the surrounding colour, are shown to significantly affect the perceived whiteness. A colour appearance model including simultaneous contrast effects  (CIECAM02-m2), earlier tested on coloured surfaces, is successfully applied to perceived whiteness. A recently proposed extension of the Kubelka-Munk light scattering model including fluorescence for turbid media of finite thickness is successfully tested for the first time on real papers.

It is shown that the linear CIE whiteness equation fails to predict the perceived whiteness of highly white papers with distinct bluish tint. This equation is applicable only in a defined region of the colour space, a condition that is shown to be not fulfilled by many commercial office papers, although they appear white to most observers. The proposed non-linear whiteness equations give to these papers a whiteness value that correlates with their perceived whiteness, while application of the CIE whiteness equation outside its region of validity overestimates perceived whiteness.

It is shown that the quantum efficiency of two different fluorescent whitening agents (FWA) in plain paper is rather constant with FWA type, FWA concentration, filler content, and fibre type. Hence, the fluorescence efficiency is essentially dependent only on the ability of the FWA to absorb light in its absorption band.  Increased FWA concentration leads accordingly to increased whiteness. However, since FWA absorbs light in the violet-blue region of the electromagnetic spectrum, the reflectance factor decreases in that region with increasing FWA amount. This violet-blue absorption tends to give a greener shade to the paper and explains most of the observed greening and whiteness saturation at larger FWA concentrations. A red-ward shift of the quantum efficiency is observed with increasing FWA concentration, but this is shown to have a negligible effect on the whiteness value.

The results are directly applicable to industrial applications for better instrumental measurement of whiteness and thereby optimising the use of FWA with the goal to improve the perceived whiteness. In addition, a modular Monte Carlo simulation tool, Open PaperOpt, is developed to allow future spatial- and angle-resolved particle level light scattering simulation.

 

Place, publisher, year, edition, pages
Sundsvall: Mid Sweden University , 2010. , p. 94
Series
Mid Sweden University licentiate thesis, ISSN 1652-8948 ; 47
Keywords [en]
Paper Whiteness, Fluorescence Whitening Agents, Kubelka-Munk, light scattering, paper industry applications, Colour Appearance Models, CIECAM02, Monte Carlo
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:miun:diva-12143ISBN: 978-91-86073-97-8 (print)OAI: oai:DiVA.org:miun-12143DiVA, id: diva2:357563
Presentation
2010-11-09, O111, Mid Sweden University, Sundsvall, 20:30 (English)
Opponent
Supervisors
Projects
PaperOptAvailable from: 2010-10-19 Created: 2010-10-18 Last updated: 2010-10-19Bibliographically approved
List of papers
1. Whiteness assessment of paper samples at the vicinity of the upper CIE whiteness limit
Open this publication in new window or tab >>Whiteness assessment of paper samples at the vicinity of the upper CIE whiteness limit
2007 (English)In: 26th Session of the CIE, 2007Conference paper, Published paper (Refereed)
National Category
Materials Engineering
Identifiers
urn:nbn:se:miun:diva-6824 (URN)6006 (Local ID)6006 (Archive number)6006 (OAI)
Available from: 2008-12-08 Created: 2008-11-02 Last updated: 2012-12-20Bibliographically approved
2. Modelling the effect of simultaneous contrast on perceived whiteness
Open this publication in new window or tab >>Modelling the effect of simultaneous contrast on perceived whiteness
2008 (English)In: Society for Imaging Science and Technology - 4th European Conference on Colour in Graphics, Imaging, and Vision and 10th International Symposium on Multispectral Colour Science, CGIV 2008/MCS'08, The Society for Imaging Science and Technology, 2008, p. 183-188Conference paper, Published paper (Refereed)
Abstract [en]

The perceived colour from a surface does not only depend on its optical properties and the illumination. Several studies have demonstrated the simultaneous contrast effect that makes the appearance of coloured patches depend on neighbouring colours. In this study the perceived whiteness of white patches surrounded by induction fields of different shades was evaluated by asking observers to give a magnitude estimate of perceived whiteness of the patches in comparison to a white reference. The perceived whiteness of patches with identical tristimulus values was highly dependent on the shade of the induction field and the patch size did not significantly affect the perceived whiteness. The recent CIECAM02-m2 colour appearance model was tested together with two whiteness equations. A combination of ClECAM02-m2 and a non-linear whiteness equation defined in the whole colour space predicted much of the observed simultaneous contrast effect. However, the model performed better for dark induction fields than for light induction fields. The model rated patches surrounded by light blue and light yellow equally, whereas the observers clearly rated the patches with light yellow induction field as whiter than the patches with light blue induction field. A deeper analysis of the CIECAM02-m2 model indicated that the simultaneous contrast model used cannot accurately predict the change in hue for high lightness induction fields. A potential improvement for predicting contrast simultaneous effect would be to base the calculations not only on the difference between the induction field and the background, but on the difference between the patch stimulus and the induction field.

Place, publisher, year, edition, pages
The Society for Imaging Science and Technology, 2008
Keywords
simultaneous contrast effect, whiteness, colour appearance modelling, CIECAM02
National Category
Materials Engineering
Identifiers
urn:nbn:se:miun:diva-6825 (URN)2-s2.0-70349971071 (Scopus ID)6007 (Local ID)978-160560702-3 (ISBN)6007 (Archive number)6007 (OAI)
Conference
4th European Conference on Colour in Graphics, Imaging, and Vision and 10th International Symposium on Multispectral Colour Science, CGIV 2008/MCS'08; Terrassa; Spain; 9 June 2008 through 13 June 2008; Code 77574
Available from: 2008-12-08 Created: 2008-11-02 Last updated: 2016-09-26Bibliographically approved
3. Quantum efficiency of fluorescent dyesin different furnishes
Open this publication in new window or tab >>Quantum efficiency of fluorescent dyesin different furnishes
(English)Manuscript (preprint) (Other academic)
Abstract [en]

A recently proposed model for the radiative properties of optically thick fluorescentturbid media of finite thickness (Kokhanovsky, JOSA A, 26(8), p1896) is successfullyapplied to uncoated papers produced at different thicknesses. It is found that thequantum efficiency of the FWA is almost independent of the fibre type, FWA type,FWA concentration and filler additive concentrations used in this study. The scatteringcoefficient is however dependent on the FWA concentration. The absorptioncoefficient depends on the adsorption of the FWA in the furnish and is function ofthe sample thickness and of the FWA type, at equal amount of FWA used in the papermakingprocess. The results open for a estimation of the model parameters asfunction of the FWA concentration and furnish. This is necessary in order to use themodel for optimizing fluorescence in the paper and textile industries.

Keywords
Fluorrescence whitening agents, Kubelka-Munk, paper, light scattering modelling, fluorescence
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:miun:diva-12141 (URN)
Projects
PaperOpt
Available from: 2010-10-18 Created: 2010-10-18 Last updated: 2010-11-29Bibliographically approved
4. Limitations of the efficiency of fluorescent whitening agents in uncoated paper
Open this publication in new window or tab >>Limitations of the efficiency of fluorescent whitening agents in uncoated paper
2011 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, no 3, p. 319-328Article in journal (Refereed) Published
Abstract [en]

The fluorescence efficiency of one fluorescent whitening agent (FWA) inuncoated and unfilled paper was characterised at different FWA concentrations. An extendedKubelka-Munk model proposed earlier by several authors was applied to quantify the effect onCIE whiteness of absorption of the FWA in the visible spectrum . At high FWA concentration,chemical interactions slightly modify the emission spectrum of the FWA, and the quantumefficiency depends on the FWA concentration. This effect has however a negligible effect onthe CIE whiteness for FWA concentrations used in practice. The overlap of the absorption andemission bands of the FWA is shown to be the main cause of greening (a shift of thechromaticity towards green) and saturation of the fluorescence effect. With increasing FWAconcentration, the positive effect of fluorescence is neutralised by the reduction of thereflectance factor in the violet-blue region of the spectrum induced by a significant absorptionof the FWA in that region.

Keywords
Fluorescence, paper, fluorescence whitening agents, greening, whiteness
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:miun:diva-12142 (URN)10.3183/NPPRJ-2011-26-03-p319-328 (DOI)000294524200010 ()2-s2.0-80052349477 (Scopus ID)
Projects
PaperOpt
Available from: 2010-10-18 Created: 2010-10-18 Last updated: 2017-12-12Bibliographically approved
5. Open source Monte carlo simulation platform for particle level simulation of light scattering from generated paper structures
Open this publication in new window or tab >>Open source Monte carlo simulation platform for particle level simulation of light scattering from generated paper structures
2009 (English)In: Papermaking Research Symposium, 2009Conference paper, Published paper (Refereed)
Keywords
light scattering, fluorescence, paper strucutre modelling
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:miun:diva-9122 (URN)978-951-27-1038-6 (ISBN)
Projects
PaperOpt
Available from: 2009-10-02 Created: 2009-06-09 Last updated: 2012-12-20Bibliographically approved

Open Access in DiVA

fulltext(174 kB)4116 downloads
File information
File name FULLTEXT01.pdfFile size 174 kBChecksum SHA-512
57d0ddf36feef3982999c7aeea59c81c4d8a7d16aaedd8e7780acbe4ade2a06e957f3770e37664125249092254cb5c38cf284fd14820525d9bcc970d4d035d98
Type fulltextMimetype application/pdf

Authority records BETA

Gustafsson Coppel, Ludovic

Search in DiVA

By author/editor
Gustafsson Coppel, Ludovic
By organisation
Department of Natural Sciences, Engineering and Mathematics
Atom and Molecular Physics and Optics

Search outside of DiVA

GoogleGoogle Scholar
Total: 4116 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 2705 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf