Energy characterization and optimization of image sensing toward continuous mobile vision

Robert Likamwa, Bodhi Priyantha, Matthai Philipose, Lin Zhong, Paramvir Bahl

Research output: Chapter in Book/Report/Conference proceedingConference contribution

98 Scopus citations

Abstract

A major hurdle to frequently performing mobile computer vision tasks is the high power consumption of image sensing. In this work, we report the first publicly known experimental and analytical characterization of CMOS image sensors. We find that modern image sensors are not energy-proportional: energy per pixel is in fact inversely proportional to frame rate and resolution of image capture, and thus image sensor systems fail to provide an important principle of energy-aware system design: trading quality for energy efficiency. We reveal two energy-proportional mechanisms, supported by current image sensors but unused by mobile systems: (i) using an optimal clock frequency reduces the power up to 50% or 30% for low-quality single frame (photo) and sequential frame (video) capturing, respectively; (ii) by entering low-power standby mode between frames, an image sensor achieves almost constant energy per pixel for video capture at low frame rates, resulting in an additional 40% power reduction. We also propose architectural modifications to the image sensor that would further improve operational efficiency. Finally, we use computer vision benchmarks to show the performance and efficiency tradeoffs that can be achieved with existing image sensors. For image registration, a key primitive for image mosaicking and depth estimation, we can achieve a 96% success rate at 3 FPS and 0.1 MP resolution. At these quality metrics, an optimal clock frequency reduces image sensor power consumption by 36% and aggressive standby mode reduces power consumption by 95%.

Original languageEnglish (US)
Title of host publicationMobiSys 2013 - Proceedings of the 11th Annual International Conference on Mobile Systems, Applications, and Services
Pages69-81
Number of pages13
DOIs
StatePublished - Aug 12 2013
Externally publishedYes
Event11th Annual International Conference on Mobile Systems, Applications, and Services, MobiSys 2013 - Taipei, Taiwan, Province of China
Duration: Jun 25 2013Jun 28 2013

Publication series

NameMobiSys 2013 - Proceedings of the 11th Annual International Conference on Mobile Systems, Applications, and Services

Other

Other11th Annual International Conference on Mobile Systems, Applications, and Services, MobiSys 2013
CountryTaiwan, Province of China
CityTaipei
Period6/25/136/28/13

Keywords

  • Computer vision
  • Energy efficiency
  • Energy proportionality
  • Image sensor
  • Mobile systems

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Computer Science Applications

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  • Cite this

    Likamwa, R., Priyantha, B., Philipose, M., Zhong, L., & Bahl, P. (2013). Energy characterization and optimization of image sensing toward continuous mobile vision. In MobiSys 2013 - Proceedings of the 11th Annual International Conference on Mobile Systems, Applications, and Services (pp. 69-81). (MobiSys 2013 - Proceedings of the 11th Annual International Conference on Mobile Systems, Applications, and Services). https://doi.org/10.1145/2462456.2464448