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Evaluation of Readability of displays in Bright Surroundings
KTH, School of Electrical Engineering (EES), Signal Processing.
2014 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

With the wide spread of wireless technology, many devices, such as tablets,

smartphones, notebooks, fixed and portable navigation systems are becoming

immensely convenient to access and are making a significant contribution to our

daily life. Compared to conventional PC, portable devices are used at different

times of the day and in various conditions and environments, both indoors and

outdoors. As a consequence, devices need to be adaptive and adaptable to a

wide range of use contexts and conditions. It is often argued that contextual

factors, such as the ambient illuminance in relation to characteristics of the

display (e.g., surface treatment, size, screen reflectance, and display luminance)

may have a strong influence on the use of such devices and corresponding user

experiences. Yet, the current understanding of these influence factors is still

rather limited. Therefore, in this thesis work, emphasis is given particularly to

the impact of lighting on readability, visual performance and affective state.

As a first step, a preparatory investigation focusing on the objective measure-

ment of display luminance and contrast, display gloss, and luminance in different

scenes, took place. For this first step, a large number of tablet and laptop dis-

plays were evaluated. This preparatory investigation served as a complement

to and as an input for step two, namely a subjective study with human test

subjects which was organized in a controlled lab environment.

In the subjective test (N=18), different types of displays, luminance settings

and lighting conditions were included to investigate the impact on display read-

ability. The results of subjective tests indicate that for matte, visual acuity

and reading speed is both impaired by the increase of ambient light luminance.

However, they are compensated effectively by the increase of display luminance

when it is below 500-600 cd/

m2. Compared with matte display, the glossy dis-

play shows to be more robust in relation to the ambient light, though it indeed

has a negative effect on visual acuity and reading speed. However, for subjective

feelings, there is no significant difference between the two displays. Both of them

are influenced by the ambient light only. In the post-experiment evaluation of

the preference of displays, the majority (61%) of the test subjects indicated a

preference for the glossy display.

Abstract [sv]

I och med spridningen av tradlos teknologi, blir enheter sasom surfplattor,

smarta mobiler och GPS:er alltmer anvandbara och blir darmed en allt viktigare

del av var vardag. Jamfort med en vanlig dator, anvands dessa barbara enheter

i manga olika sammanhang i olika miljoer, bade inomhus och utomhus. Darfor

maste de kunna anpassa sig till olika miljoer och forutsattningar. Det pastas

ofta att omgivande faktorer sasom bakgrundsbelysning och hur dessa samverkar

med skarmens egenskaper (yta, storlek, reflektans och ljusstyrka) kan han en

viktig inverkan pa anvandningen av sadana enheter och motsvarande anvan-

darupplevelse. Trots det ar var forstaelse av dessa faktorer fortfarande ratt

begransad. Darfor fokuserar detta examensarbete specifikt pa hur lasbarhet,

lasupplevelse och humor paverkas av ljusforhallandena.

Som ett forsta steg, gjordes en forberedande studie med objektiva matningar

av displayers ljusstyrka, kontrast och matthet i olika omgivningar. I detta forsta

steg, utvarderades ett stort antal olika lasplattor och laptop-skarmar. Denna in-

ledande undersokning bildade ett komplement och underlag till det andra steget,

vilket var en subjektiv anvandbarhetsstudie med ett antal forsokspersoner, or-

ganiserad i en reglerad labbmiljo.

I anvandartesten (N=18), undersoktes lasbarheten for olika typer av dis-

player under olika ljusstyrkeinstallningar och omgivande ljusforhallanden. Re-

sultaten av anvandartesten indikerar att for matta displayer, paverkas skarpa

och lashastighet negativt da den omgivande ljusstyrka okar. Detta kan dock

effektivt kompenseras genom att oka displayens ljusstyrka, da den ar under

500-600 cd/m2. I jamforelse med matta displayer, visar sig blanka displayer

vara mer robusta mot variationer i bakgrundsbelysningen. Daremot, for sub-

jektiva kanslan, ar det ingen signifikant skillnad mellan de tva displaytyperna.

I bada fallen ar det bara omgivande belysningen som paverkar. I en utvardering

efter avslutat experiment, foredrog en majoritet (61%) av forsokspersonerna den

blanka displayen.

Place, publisher, year, edition, pages
2014. , 62 p.
EES Examensarbete / Master Thesis, XR-EE-SB 2014:014
Keyword [en]
Subjective Study, Readability, Ambient light, Outdoor, Matte display, Glossy display, Portable
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:kth:diva-160946OAI: diva2:792765
Educational program
Master of Science - Wireless Systems
Available from: 2015-03-05 Created: 2015-03-05 Last updated: 2015-03-05Bibliographically approved

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