Elastic Algorithms for Region of Interest Video Compression, with Application to Mobile Telehealth
Sira Rao and Dr. Nikil JayantMultimedia Communications Lab
School of Electrical and Computer EngineeringGeorgia Institute of Technology, Atlanta, GA
Pilot Tests on Training Sequences
Randomly Assigned
Video Sample Number
Bit Rate
(kbps)
Feature Sets Adequate to Assess?
Clinical Assessment
Rn1 100
Rib Retraction
Oral Cyanosis
Tripod Posture
1-5
1-5
1-5
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Rib Retraction
Oral Cyanosis
Tripod Posture
1-5
1-5
1-5
Comments
Comments
Comments
Rn10 1000
Rib Retraction
Oral Cyanosis
Tripod Posture
1-5
1-5
1-5
Comments
Comments
Comments
Encoder State Machine
Sufficient bits for State 1?
Sufficient bits for State 2?
Sufficient bits for State 3?
START
{ML,ML} {ML,PL} {ML,DL}
YES YES YES
NO NO NO
STOP
…
…
Encoder State Table – Region-Quality Mappings
ML PL DL BE
ML 1 2 3 4
PL 5 6 7
DL 8 9
BE 10
Mapping from bits to quality levels may not always be satisfactorily achieved
Different medical features with likely different compression limits on PL, DL
Nominal mapping possibly the average value
Thus, when ROI not of PL or DL quality when current state indicates it to be so, transition to a lower state in the same row to increase R_ROI
State Transitions due to Inadequate Quality
Real-time Video in Mobile Telehealth – Scenario
Wireless NetworkWireless Network
Mobile ExpertVideo ClientHomeHospitalCommunity
Mobile PatientFuture Scenario
ER-PICUPatient
Medical CenterInformation
Server
Manual trigger of inadequate quality within the ROI
Automatic trigger through a PSNR difference method
Based on expectation of minimal difference in ROI and BKGRND quality
Offsets underestimation in nominal mappings PSNR_TH state dependent i.e. expect higher
differences where ROI and BKGRND have different quality abstractions (e.g. state 7 (PL ROI, BE BKGRND) and state 5 (PL ROI, PL BKGRND))
0__
1__
___
FLAGQUALITYROI
else
FLAGQUALITYROI
THPSNRPSNRBKGRNDPSNRROIIf
Detection of Transitions600kbps
0.4028.6
600kbps0.1925.2
900kbps0.5629.5
900kbps0.2927.7
600kbps0.3620.4
600kbps0.1918.0
900kbps0.5321.1
900kbps0.2918.8
Quality Level ROI BKGRND
PL 0.3157 0.3157
DL 0.2104 0.2104
BE - 0.1052
BE_MIN - 0.0526
600 600 900 900 1200 1200
ROI BKGRND ROI BKGRND ROI BKGRND
Foreman 0.40 0.12 0.56 0.21 0.62 0.31
Flower 0.36 0.14 0.53 0.21 0.58 0.33
Football 0.38 0.13 0.55 0.21 0.62 0.31
MPEG2 0.19 0.19 0.29 0.29 0.39 0.39
Performance Results