Whiteness is a fundamental property of paper. But what is whiteness exactly, how does it arise, and how do you measure whiteness? How difficult can it really be to produce good color prints?
Per Edström pursues research on mathematical modeling and scientific computing. His model is replacing an old model that has been used by the paper and printing industries since the 1930s.
“Light that hits paper penetrates a bit. Some of it is absorbed and disappears, while some scatters in other directions,” says Per Edström. “This is affected by fibers and fillers in the paper, and by various additives and ink. This is a rather complex process that gives paper its visual appearence. Tiny constituents in the paper provide the light with many surfaces to scatter against, and this helps create a lighter paper. Ink, on the other hand, absorbs light of different wavelengths, producing color. The total impression is also dependent on how all of the components in the paper are distributed, for example, how the ink penetrates into the paper. Finally, the color experience depends on how the eye and the brain interpret the visual impression, all of which means that it is not so simple to understand these phenomena in detail.”
Per Edström has delved deeply into numerical solution methods for systems of coupled integro-differential equations. There are many applications for this, one of which is to describe how light interacts with paper and print to produce a visual experience.
“I like to challenge my students with a little contest at the end of a lecture on whiteness,” says Per Edström. “They have fifteen minutes, and the student who submits the whitest paper will win a prize. Even though I have had many enthusiastic students, I have yet to award a prize. Contact me if you want to know why. And how white is a piece of paper anyway?”
Caption picture one(above):
This image is taken perpendicularly to the paper, which is illuminated in 45 degree angle. The light penetrates into the paper and meets the inks, some wavelenghts are absorbed and the light that reaches the camera carries the colour information from the image.
Caption picture two (below) This image is illuminated in 75 degree angle, and the camera is placed oppositely in 75 degree angle. The light does not penetrate into the paper but is reflected on the surface. The light therefore does not reach the inks, and the light that reaches the camera only carries some contrast information from the image surface. This is exactly the effect that comes from being blinded by a glossy commercial that is held in the “wrong” direction – nothing of the image colour is visible, only the mittor reflection of the illumination and some contrast from the paper surface.
Questions can be submitted to:
Per Edström, phone: +46 (0)611-862 44 or cell phone: +46 (0)73-760 21 51. E-mail: per.edstrom@miun.se
26 April, 2013 - Mittuniversitetet
On the 7th of May, ABBA The Museum and The Swedish Music Hall of Fame in Stockholm, Sweden, will open their gates to visitors from around the world. Current research at the European Tourism Research Institute (ETOUR), Mid Sweden University, shows that half of the ABBA fans have travelled ten times or more because of their interest in ABBA.
19 November, 2012 - Mittuniversitetet
Researchers from Sportstech Additive Manufacturing Group at Mid Sweden University have verified the patented technology of the Swedish company Exmet AB by succeeding in making the world first sample of iron based bulk metallic glass (BMG, also amorphous metal or glassy alloy) using electron beam manufacturing technology. This may be a breakthrough in the manufacturing of BMG components.
14 November, 2011 - Mittuniversitetet
In the last couple of years, the two small American towns of Forks and La Push have been visited by hundreds, sometimes thousands, of people a day. These visitors photograph the local school, doctor’s office, and residential houses – all in pursuit of an authentic Twilight experience. Tourism researchers at Mid Sweden University are now releasing the first book about the fans and the tourism that has emerged, ”I populärkulturturismens fotspår – Twilight + Vacation = Twication©” [Following the footprints of popular culture tourism – Twilight + Vacation = Twication©].
23 February, 2011 - Mittuniversitetet
FSCN, the Fibre Science and Communication Network research center at Mid Sweden University will pursue research on energy-efficient production of mechanical and chemimechanical pulping processes. This will be done in collaboration with the companies SCA, Stora Enso, Holmen, Metso, and Andritz. Mid Sweden University will receive SEK 36 million from the Knowledge Foundation, and the business community will make research commitments corresponding in value to the Knowledge Foundation investment. On top of this, the University is providing SEK 12 million.
Expertsvar, The Swedish Research Council, Hantverkargatan 11B, Stockholm SWEDENPhone +46(0)8 546 44 000
P.O. Box 1035, SE-101 38 Stockholm, expertsvar@vr.se
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