Security and Usability Challenges of Moving-Object CAPTCHAs: Decoding Codewords in Motion.
Yi XuGerardo ReynagaSonia ChiassonJan-Michael FrahmFabian MonrosePaul C. van OorschotPublished in: USENIX Security Symposium (2012)
Keyphrases
- motion patterns
- moving objects
- image sequences
- motion field
- motion model
- spatio temporal
- camera motion
- security problems
- space time
- optical flow
- multiple moving objects
- object motion
- motion analysis
- video sequences
- motion segmentation
- security issues
- moving observer
- access control
- moving object detection
- static background
- moving object segmentation
- humanoid robot
- viterbi algorithm
- vector quantization
- motion parameters
- dynamic scenes
- video surveillance
- moving points
- security requirements
- consecutive frames
- background subtraction
- information security
- human motion
- moving camera
- intrusion detection
- detection algorithm
- detection of moving objects
- feature points
- decoding algorithm
- security policies
- object tracking
- background modeling
- image motion
- motion boundaries
- visual motion
- video coding
- hand gestures
- motion detection
- video streams
- frame differencing
- motion compensation