1 / 13
SPLAB, VUT
Klepnutím lze upravit styl předlohy Klepnutím lze upravit styl předlohy nadpisů. nadpisů. www.splab.cz
Soft biometric traits in de‐identification process ‐ Hair Jiri Prinosil Jiri Mekyska Zdenek Smekal
Brno University of Technology
2 / 13
SPLAB, VUT
Hair and hair color Klepnutím lze upravit styl předlohy nadpisů.
• Supplementary trait for identification • Hair color can be used for dividing people into sub‐groups – Assigning hair color index to a person in a video sequence – These indices can be used as filtering clue when searching in databases
Brno University of Technology
3 / 13
SPLAB, VUT
Hair segmentation method Klepnutím lze upravit styl předlohy nadpisů. • State of the art methods – static images only – simple background – high processing time
• proposed method – video‐sequences – complex background – real‐time processing
Brno University of Technology
4 / 13
SPLAB, VUT
Hair segmentation method Klepnutím lze upravit styl předlohy nadpisů. • Face detection stage – position of face detector is obtained – positions of eyes and nose are obtained – Viola‐Jones detector – face tracker based on motion estimation using rectangular grid
Brno University of Technology
5 / 13
SPLAB, VUT
Hair segmentation method Klepnutím lze upravit styl předlohy nadpisů. • Background subtraction – silhouette obtained
• Head segmentation – head is obtained by using face position and silhouette
Brno University of Technology
6 / 13
SPLAB, VUT
Hair segmentation method Klepnutím lze upravit styl předlohy nadpisů.
• Skin segmentation
– the hair area is given as the difference between head and skin segment – flood‐filling approach is used – flooding starts from different seed points – positions of seed‐points are set according to positions of eyes and nose
Brno University of Technology
7 / 13
SPLAB, VUT
Hair segmentation method Klepnutím lze upravit styl předlohy nadpisů. • Skin segmentation – to suppress propagating of flood to hair area, only a compact part around a particular seed‐point is taken from the flood area – finally, a skin area is determined as a convex hull of union of selected parts around different seed points
• Hair segmentation – hair is given a the difference between hair and skin
Brno University of Technology
SPLAB, VUT
8 / 13
Hair segmentation method Klepnutím lze upravit styl předlohy nadpisů. • Results – Tested on 28 video‐sequences of avg. length of 4 seconds – Compared with ground‐truth masks Measure Precision Recall
Average
Median
0.84% 0.49%
0.92% 0.48%
– Processing times per frame Phase Face detection Background subtraction Head and skin segmentation
Average time [ms] 121 55 38
Brno University of Technology
SPLAB, VUT
9 / 13
Color estimation Klepnutím lze upravit styl předlohy nadpisů. • Experimental setup – Tested on 28 people in available video‐sequences – A color of each subject was subjectively classified into one of five categories (black, brown, blond, red, gray/white) as a reference
• Color estimation model – HSV space is equally spaced to 10 ranges for every dimension – 1000 HSV sub‐spaces are obtained – Assumption, that colors in each sub‐space are similar – Mean value of each sub‐space is subjectively classified Brno University of Technology
10 / 13
SPLAB, VUT
Color estimation Klepnutím lze upravit styl předlohy nadpisů. • Color estimation – Color of each hair pixel is evaluated using the described model – Histogram of colors in one frame is calculated – Histograms of multiple frames are summed and the biggest bin determines the hair color of a person in video‐ sequence
Brno University of Technology
SPLAB, VUT
11 / 13
Color estimation Klepnutím lze upravit styl předlohy nadpisů. • Results – Tested on 28 video‐sequences Man. extracted hair masks
Aut. extracted hair masks
Estimation
Blk.
Brw.
Bld.
Red
Wht.
Perc.
Blk.
13
1
0
0
0
92.9%
Brw.
2
5
0
0
1
62.5%
Bld.
0
0
2
0
1
66.6%
Red
0
0
0
1
0
100%
Wht.
0
0
0
0
2
100%
Subj. evaluation
Subj. evaluation
Estimation Blk.
Brw.
Bld.
Red
Wht.
Perc.
Blk.
13
1
0
0
0
92.9%
Brw.
1
6
0
0
1
75.0%
Bld.
0
0
2
0
1
66%
Red
0
0
0
1
0
100%
Wht.
0
0
0
0
2
100%
– Results are different only in one case Brno University of Technology
12 / 13
SPLAB, VUT
Experiment Klepnutím lze upravit styl předlohy nadpisů.
Brno University of Technology
13 / 13
SPLAB, VUT
Experiment Klepnutím lze upravit styl předlohy nadpisů.
Brno University of Technology
14 / 13
SPLAB, VUT
Experiment Klepnutím lze upravit styl předlohy nadpisů.
Brno University of Technology
15 / 13
SPLAB, VUT
Experiment Klepnutím lze upravit styl předlohy nadpisů.
Brno University of Technology
16 / 13
SPLAB, VUT
Klepnutím lze upravit styl předlohy Klepnutím lze upravit styl předlohy nadpisů. nadpisů. www.splab.cz
Brno University of Technology
