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