What's wrong with mean-squared error?
Digital images and human vision
Evaluation of subjective video quality of mobile devices
Proceedings of the 13th annual ACM international conference on Multimedia
MobileASL:: intelligibility of sign language video as constrained by mobile phone technology
Proceedings of the 8th international ACM SIGACCESS conference on Computers and accessibility
Variable frame rate for low power mobile sign language communication
Proceedings of the 9th international ACM SIGACCESS conference on Computers and accessibility
A web-based user survey for evaluating power saving strategies for deaf users of mobileASL
Proceedings of the 12th international ACM SIGACCESS conference on Computers and accessibility
Adaptive downsampling to improve image compression at low bit rates
IEEE Transactions on Image Processing
Rate-constrained coder control and comparison of video coding standards
IEEE Transactions on Circuits and Systems for Video Technology
Towards human-centered optimization of mobile sign language video communication
ACM SIGACCESS Accessibility and Computing
Proceedings of the 15th International ACM SIGACCESS Conference on Computers and Accessibility
Proceedings of the 15th International ACM SIGACCESS Conference on Computers and Accessibility
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Video and image quality are often objectively measured using peak signal-to-noise ratio (PSNR), but for sign language video, human comprehension is most important. Yet the relationship of human comprehension to PSNR has not been studied. In this survey, we determine how well PSNR matches human comprehension of sign language video. We use very low bitrates (10-60 kbps) and two low spatial resolutions (192×144 and 320×240 pixels) which may be typical of video transmission on mobile phones using 3G networks. In a national online video-based user survey of 103 respondents, we found that respondents preferred the 320×240 spatial resolution transmitted at 20 kbps and higher; this does not match what PSNR results would predict. However, when comparing perceived ease/difficulty of comprehension, we found that responses did correlate well with measured PSNR. This suggests that PSNR may not be suitable for representing subjective video quality, but can be reliable as a measure for comprehensibility of American Sign Language (ASL) video. These findings are applied to our experimental mobile phone application, MobileASL, which enables real-time sign language communication for Deaf users at low bandwidths over the U.S. 3G cellular network.