The kindest cut: enhancing the user experience of mobile tv through adequate zooming

ABSTRACT

The growing market of Mobile TV requires automated adaptation of standard TV footage to small size displays. Especially extreme long shots (XLS) depicting distant objects can spoil the user experience, e.g. in soccer content. Automated zooming schemes can improve the visual experience if the resulting footage meets user expectations in terms of the visual detail and quality but does not omit valuable context information. Current zooming schemes are ignorant of beneficial zoom ranges for a given target size when applied to standard definition TV footage. In two experiments 84 participants were able to switch between original and zoom enhanced soccer footage at three sizes - from 320x240 (QVGA) down to 176x144 (QCIF). Eye tracking and subjective ratings showed that zoom factors between 1.14 and 1.33 were preferred for all sizes. Interviews revealed that a zoom factor of 1.6 was too high for QVGA content due to low perceived video quality, but beneficial for QCIF size. The optimal zoom depended on the target display size. We include a function to compute the optimal zoom for XLS depending on the target device size. It can be applied in automatic content adaptation schemes and should stimulate further research on the requirements of different shot types in video coding.

REFERENCES

• 1: 3G.co.uk, 3G WCDMA Will Receive the Highest CAPEX Investment by Mobile Operators., http://www.3g.co.uk/PR/Sept2006/3633.htm. 2006
• 2: G. Agarwal , A. Anbu , A. Sinha, A fast algorithm to find the region-of-interest in the compressed MPEG domain, Proceedings of the 2003 International Conference on Multimedia and Expo, p.133-136, July 06-09, 2003
• 3: Bennett, A. G. Ophthalmic test types Br. J. Physiol. Opt., 22, p. 238--71, 1965.
• 4: Cane, A., Football forces mobile television out of the lab., http://www.ft.com/cms/s/70cea448-0123-11db-af16-0000779e2340,dwp_uuid80ae8cee-4a2f-11da-b8b1-0000779e2340.html. 2006
• 5: Corey, G. P., Clayton, M. J., Cupery, K. N. Scene Dependence of image quality Society of Photographic Scientists and Engineers, 27 (1), p. 9--13, Jan-Feb 1983.
• 6: Dal Lago, G., Microdisplay Emotions., http://www.srlabs.it/articoli_uk/ics.htm. 2006
• 7: Frieser, H. & Biedermann, K. Experiments on image quality in relation to the modulation transfer function and graininess of photographs Photographic Science and Engineering, 7 (28) 1963.
• 8: Gwinn, E. & Hughlett, M., Mobile TV for your cell phone., Chicago Tribune. at: http://home.hamptonroads.com/stories/story.cfm?story=93423&ran38197 2005
• 9: Holmstrom, D. Content based pre-encoding video filter for mobile TV. Umea University, 2003
• 10: ITU-R Methodology for the subjective assessment of the quality of television pictures. (Rep. No. BT.500-7), 2004.
• 11: Jesty, L. C. The relation between picture size, viewing distance and picture quality in Proc. Inst. Electr. Eng., p. 425--39, 1958
• 12: Jumisko-Pyykkö, S. & Hääkkinen, J. "I would like see the face and at least hear the voice": Effects of Screen Size and Audio-video Bitrate Ratio on Perception of Quality in Mobile Television in Proceedings of Euro ITV '06, 2006
• 13: Kingslake, R. Lenses on Photography New York, NY: Barnes & Co, 1963
• 14: Knoche, H. & McCarthy, J. Mobile Users' Needs and Expectations of Future Multimedia Services in Proceedings of the WWRF12, 2004
• 15: Hendrik Knoche , John D. McCarthy, Design requirements for mobile TV, Proceedings of the 7th international conference on Human computer interaction with mobile devices & services, September 19-22, 2005, Salzburg, Austria [doi>10.1145/1085777.1085789]
• 16: Hendrik Knoche , John D. McCarthy , M. Angela Sasse, Can small be beautiful?: assessing image resolution requirements for mobile TV, Proceedings of the 13th annual ACM international conference on Multimedia, November 06-11, 2005, Hilton, Singapore [doi>10.1145/1101149.1101331]
• 17: Knoche, H., McCarthy, J., Sasse, M. A. A close-up on Mobile TV: The effect of low resolutions on shot types in Proc. of EuroITV '06, 2006
• 18: Stephan Kopf , Fleming Lampi , Thomas King , Wolfgang Effelsberg, Automatic scaling and cropping of videos for devices with limited screen resolution, Proceedings of the 14th annual ACM international conference on Multimedia, October 23-27, 2006, Santa Barbara, CA, USA [doi>10.1145/1180639.1180849]
• 19: KPMG Consumers and Convergence Challenges and opportunities in meeting next generation customer needs, 2006.
• 20: Lienhart, R. Comparison of Automatic Shot Boundary Detection Algorithms in Proc.of SPIE Storage and Retrieval for Image and Video Databases VII, p. 290--301, 1999
• 21: Arch C. Luther, Principles of Digital Audio and Video, Artech House, Inc., Norwood, MA, 1997
• 22: John D. McCarthy , M. Angela Sasse , Dimitrios Miras, Sharp or smooth?: comparing the effects of quantization vs. frame rate for streamed video, Proceedings of the SIGCHI conference on Human factors in computing systems, p.535-542, April 24-29, 2004, Vienna, Austria [doi>10.1145/985692.985760]
• 23: Nemethova, O., Ries, M., Dantcheva, S., Fikar, S., Rupp, M. Test Equipment of Time-Variant Subjective Perceptual Video Quality in Mobile Terminals in Proc. of HCI, 2005
• 24: Nemethova, O., Zahumensky, M., Rupp, M. Preprocessing of Ball Game Video-Sequences for Robust Transmission over Mobile Networks in Proceedings of the CIC 2004 The 9th CDMA International Conference, 2004
• 25: Seo, K. & Kim, C. A Context-Aware Video Display Scheme for Mobile Devices in R. Creutzburg, J. H. Takala, & C. W. Chen (Eds.) Proceedings of SPIE-IS&T, p. 278--87, SPIE-IS&T, 2006
• 26: Silbergleid, M. & Pescatore, M. The Guide To Digital Television (3rd ed.) Miller Freeman Psn Inc, 2000
• 27: Sinha, A. & Agarwal, G. A method of dynamic cropping and resizing of video frames in DVB-H to Mobile in GPSx 2005, 2005
• 28: Södergård, C. Mobile television - technology and user experiences Report on the Mobile-TV project (Rep. No. P506) VTT Information Technology, 2003.
• 29: Seungho Song , Youjip Won , Injae Song, Empirical study of user perception behavior for mobile streaming, Proceedings of the tenth ACM international conference on Multimedia, December 01-06, 2002, Juan-les-Pins, France [doi>10.1145/641007.641076]
• 30: Sporer, T. Evaluating Small Impairments with the Mean Opinion Scale - Reliable or Just a Guess? in 101st Audio Engineering Society Convention, 1996
• 31: Stanger, L., Submission to G-2.1.6 Progress Report of Task Force to define a Unit of Measure and Means of Calibration for Video Quality Analysis., http://grouper.ieee.org/groups/videocomp/lsrpt3d1.html. 2006
• 32: Sylvers, E., Italia hails growth of its mobile TV service., http://www.iht.com/articles/2006/07/20/technology/italia.php. 2006
• 33: Thompson, R. Grammar of the shot Elsevier Focal Press, 1998
• 34: Voldhaug, J. E., Johansen, S., Perkis, A. Automatic Football Video Highlights Extraction in NORSIG-05, 2005
• 35: Westerink, J. H. & Roufs, J. A. Subjective Image Quality as a Function of Viewing Distance, Resolution, and Picture Size SMPTE Journal, 1989.

INDEX TERMS

Primary Classification:
  H. Information Systems
  H.5 INFORMATION INTERFACES AND PRESENTATION (I.7)
      H.5.1 Multimedia Information Systems
          Subjects: Evaluation/methodology

Additional Classification:
  H. Information Systems
  H.5 INFORMATION INTERFACES AND PRESENTATION (I.7)
      H.5.2 User Interfaces (D.2.2, H.1.2, I.3.6)
          Subjects: User-centered design

General Terms:
Design, Experimentation, Human Factors

Keywords:
eye-tracking, mobile devices, mobile tv, multimedia content enhancement, user experience, video, zooming