Featured Research

from universities, journals, and other organizations

How White Is A Paper?

Date:
October 23, 2009
Source:
Swedish Research Council
Summary:
Whiter paper and better color reproduction are examples of important competitive advantages on an international market. But how white is a paper? And why do vacation photos turn out so dark if you don't buy expensive photo paper? Research from Sweden has resulted in a new generation of computational tools for simulation of light in paper and print.

Image 1 is taken perpendicularly to the paper, which is illuminated in 45 degree angle. The light penetrates into the paper and meets the inks, some wavelengths are absorbed and the light that reaches the camera carries the colour information from the image. Image 2 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 mirror reflection of the illumination and some contrast from the paper surface.
Credit: Image courtesy of Swedish Research Council

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?

Related Articles


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 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 appearance. 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."

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 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?"


Story Source:

The above story is based on materials provided by Swedish Research Council. Note: Materials may be edited for content and length.


Cite This Page:

Swedish Research Council. "How White Is A Paper?." ScienceDaily. ScienceDaily, 23 October 2009. <www.sciencedaily.com/releases/2009/10/091022101547.htm>.
Swedish Research Council. (2009, October 23). How White Is A Paper?. ScienceDaily. Retrieved February 26, 2015 from www.sciencedaily.com/releases/2009/10/091022101547.htm
Swedish Research Council. "How White Is A Paper?." ScienceDaily. www.sciencedaily.com/releases/2009/10/091022101547.htm (accessed February 26, 2015).

Share This


More From ScienceDaily



More Matter & Energy News

Thursday, February 26, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Vibrating Bicycle Senses Traffic

Vibrating Bicycle Senses Traffic

Reuters - Innovations Video Online (Feb. 26, 2015) — Dutch scientists have developed a smart bicycle that uses sensors, wireless technology and video to warn riders of traffic dangers. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
In Japan, Robot Dogs Are for Life -- And Death

In Japan, Robot Dogs Are for Life -- And Death

AFP (Feb. 25, 2015) — Robot dogs are the perfect pet for some in Japan who go to repairmen-turned-vets when their pooch breaks down - while a full Buddhist funeral ceremony awaits those who don&apos;t make it. Duration: 02:40 Video provided by AFP
Powered by NewsLook.com
London Show Dissects History of Forensic Science

London Show Dissects History of Forensic Science

AFP (Feb. 25, 2015) — Forensic science, which has fascinated generations with its unravelling of gruesome crime mysteries, is being put under the microscope in an exhibition of real criminal investigations in London. Duration: 00:53 Video provided by AFP
Powered by NewsLook.com
Researchers Replace Damaged Hands With Prostheses

Researchers Replace Damaged Hands With Prostheses

Newsy (Feb. 25, 2015) — Scientists in Austria have been able to fit patients who&apos;ve lost the use of a hand with bionic prostheses the patients control with their minds. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins