Monday, February 2, 2009

Current user research in the context of Mobile3DTV

Related user studies in the field of 3DTV and especially in the field of mobile TV, one can realize a big change in the field of user-centered design. Current research has introduced user-centered approaches to study user’s needs and expectations about novel systems and services. This allows better understanding of the impact of critical system components. The cyclic character of user-centered design is standardized in ISO 13407 [1].

Subjective quality has usually been studied quantitatively based on requirements of the International Telecommunication Union (ITU) [2] offering guidelines to study quality perception studies in controlled, laboratory environments. In the context of mobile television, these studies, which base on quantitative measurements of ITU recommendations, have focused on evaluating the impact of coding errors, low bitrates, and impact of changes in image size or framerates as well as bitrate share between audio and visual modalities (e.g. [3], [4], [5]). Further, there are studies into transmission errors over DVB-H channel and their impact on the perceived quality [6], but still these studies are rare.

With respect to stereo-coding, there are studies on stereo-coding errors in images and videos [7]. However, user studies in the field of 3DTV have focused more on the impact of different factors on presence, the users feeling of being there. In stereo-video content presentation, the most prominent additional features that influence the perceived quality are depth information, perceived sharpness, or naturalness (i.e. the most truthful or realistic reproduction of content) [8][9]. All these factors contribute to the concept of presence, the involvement of the user in the content; the feeling of being there [10]. Nevertheless, some work has reported simulator sickness symptoms caused by the use of stereo-video presentation. This particular impact of stereo vision adversely affects enjoyment and factors creating simulator sickness are not yet known in depth [11].

In contrast to the recommendations of the ITU, current studies in the field of mobile TV include user characteristics, usage contexts and the user’s goal of viewing. Currently there are available results of field trials or studies conducted in several countries [12][13] as well as results of prospective focus groups and online surveys [14][15]. In contrast, user studies into the field of 3DTV are still rare and Freeman’s focus group [16] is the only study which examines user requirements of 3DTV more broadly.

From the methodological point of view, there is a lot of work in progress to close the shortcomings of ITU recommendations. Researchers have introduces contextual quality evaluation procedure that is conducted in parallel to the controlled laboratory assessments [17]. Additionally, evaluation of the experienced quality of critical system components targets the future acceptability of the quality of components which were developed in isolation from the end-product [18]. A third step to understand experienced quality is to understand the interpretation of constructed quality and experienced quality factors [19].

Finally, there is one available study into the user experience of mobile 3D television. Following a methodological triangulation of online survey, focus groups and probe study to elicit user requirements, Jumisko-Pyykkö et al. [20] present a broad view on user experience of mobile TV. In all the three studies, they targeted the user experience factors of user, system and services, and contexts. Concluding their study, they present first guidelines to design user experience of mobile 3D television.

  1. ISO 13407. 1999. Human-centered design processes for interactive systems. International Standard, the International Organization for Standardization.
  2. ITU-R BT.500-11, Methodology for the Subjective Assessment of the Quality of Television Pictures, Recommendation ITU-R BT.500-11, ITU Telecom. Standardization Sector of ITU, 2002.
  3. H. Knoche, J. D. McCarthy, and M. A. Sasse, “Can small be beautiful?: assessing image resolution requirements for mobile tv,” in MULTIMEDIA ‟05: Proceedings of the 13th annual ACM international conference on Multimedia. New York, NY, USA: ACM Press, 2005, pp. 829–838.
  4. S. Winkler, S. C. Faller, “Maximizing audiovisual quality at low bitrates,” Workshop on Video Processing and Quality Metrics for Consumer Electronics. Scottsdale, United States of America: January 2005.
  5. S. Jumisko-Pyykkö, “I would like to see the subtitles and the face or at least hear the voice”: Effects of Picture ratio and Audio-video Bitrate Ratio on Perception of Quality in Mobile Television. To appear in Personalized and Mobile Digital TV Applications in Springer Multimedia Tools and Applications Series, 2007
  6. S. Jumisko-Pyykkö, Vadakital, V., Liinasuo, M. , Hannuksela M. M., Acceptance of Audiovisual Quality in Erroneous Television Sequences over a DVB-H Channel. Proceedings of Second International Workshop in Video Processing and Quality Metrics for Consumer Electronics, Scottsdale, USA, January 2006.
  7. L. B. Stelmach, Tam, W. J. (1998). Stereoscopic image coding: effect of disparate image-quality in left- and right-eye views. Signal Processing: Image Communications, 14:111–117.
  8. H. de Ridder, (1996). Naturalness and image quality: Saturation and lightness variations in color images of natural scenes. Journal of Imaging Science and Technology, 40:487–493.
  9. A. Berthold (1997). The influence of blur on the perceived quality and sensation of depth of 2D and stereo images. Technical report, ATR Human Information Processing Research Laboratories.
  10. W. IJsselsteijn, de Ridder, H., Freeman, J., and Avons, S. (2000a). Presence: Concept, determinants and measurement. Proceedings of the SPIE, 3959:520–529.
  11. Häkkinen, J., Liinasuo, M., Takatalo, J., and Nyman, G. 2006. Visual comfort with mobile stereoscopic gaming. Proceedings of SPIE. Vol. 6055
  12. Chipchase, J., Yanqing, C., Jung, Y., and Design, N. 2006. Personal Television: A Qualitative Study of Mobile TV Users. Lecture Notes in Computer Science. Vol. 4471, pp.195-204
  13. Södergård C. (ed.). 2003. Mobile television – technology and user experiences, Report on the Mobile –TV Project. Espoo: VTT Publications 506.
  14. Knoche, H. O., McCarthy, J. D. 2004. Mobile Users Needs and Expectations of Future Multimedia Services. In Proceedings of the WWRF12. Nov. 2004, Toronto, Canada
  15. Carlsson, C., Walden, P. 2007. Mobile TV - To Live or Die by Content, Proc 40th HICSS 51b.
  16. Freeman, J., Avons, S. E. 2000. Focus Group Exploration of Presence through Advanced Broadcast Services. In Proc. SPIE 3959 , 3959-3976.
  17. Jumisko-Pyykkö, S., Hannuksela, M. M. Does Context Matter in Quality Evaluation of Mobile Television? To appear in the Proceedings of 10th International Conference on Human Computer Interaction with Mobile Devices and Services (MobileHCI 2008)
  18. Jumisko-Pyykkö, S. Kumar Malamal Vadakital, V., Hannuksela, M.M. Acceptance Threshold: Bidimensional Research Method for User-Oriented Quality Evaluation Studies. To appear in International Journal of Digital Multimedia Broadcasting, 2008.
  19. Strohmeier, D. Wahrnehmungsuntersuchung von 2D vs. 3D Displays in A/V-Applikationen mittels einer kombinierten Analysemethodik, Diploma Thesis, Ilmenau University of Technology, Germany, 2007
  20. Jumisko-Pyykkö, S., Weitzel, M., Strohmeier, D. "Designing for User Experience: What to Expect from Mobile 3D TV and Video? " . Proceedings of the First International Conference on Designing Interactive User Experiences for TV and Video. October 22 - 24, 2008, Silicon Valley, California, USA.

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