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CONTEXT-BASED PEOPLE RECOGNITION in CONSUMER PHOTO COLLECTIONS
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CONTEXT-BASED PEOPLE RECOGNITION
in CONSUMER PHOTO COLLECTIONS
Markus Brenner, Ebroul Izquierdo MMV Research Group, School of Electronic Engineering and Computer Science
Queen Mary University of London, UK
{markus.brenner, ebroul.izquierdo}@eecs.qmul.ac.uk
Face Detection and Basic Recognition
Initial steps: Image preprocessing, face detection and face normalization
Descriptor-based: Local Binary Pattern (LBP) texture histograms
Similarity metric: Chi-Square Statistics
Basic face recognition: k-Nearest-Neighbor
Graph-based Recognition
Model: pairwise Markov Network (graph nodes represent faces)
Unary Potentials: likelihood of faces belonging to
particular people
Pairwise Potentials: encourage spatial smoothness,
encode exclusivity constraint and temporal domain
Topology: only the most similar faces are
connected with edges
Inference: maximum a posteriori (MAP)
solution of Loopy Belief Propagation (LBP)
Social Semantics
Individual appearance for a more effective graph
topology (used to regularize the number of edges)
Unique People Constraint models exclusivity:
a person cannot appear more than once in a photo
Pairwise co-appearance: people appearing together
bear a higher likelihood of appearing together again
Groups of people: use data mining to
discover frequently appearing social patterns
Body Detection and Recognition
… when faces are obscured or invisible
Detect upper and lower body parts
Bipartite matching of faces and bodies
Graph-based fusion of faces and clothing
f2f1
f3
Unary potential
Pairwise potential
Face
Resolve identities of people primarily by their faces
Incorporate rich contextual cues of personal photo collections
where few individual people frequently appear together
Perform recognition by considering all contextual information
at the same time (unlike traditional approaches that usually
train a classifier and then predict identities independently)
Aim
𝑢 𝑤𝑛 =1
𝑍𝑓𝑓 𝑤𝑛
Experiments Public Gallagher Dataset:
~600 photos, ~800 faces, 32 distinct people
Our dataset:
~3300 photos, ~5000 faces, 106 distinct people
All photos shot with a typical consumer camera
Considering only correctly detected faces (87%)
Te Tr
Tr
Tr
Te
Face
similarity
All samples
are independent
Te
TrTr
TrTe
Based on face
similarities
Unary potential
of every node
Te
TrTr
TrTe
Upper body
similarity
Face
similarity
Lower
body
similarity
Unary potential
of every node
...
𝑝 𝑤𝑛 ,𝑤𝑚 =
𝜏, 𝑖𝑓 𝑤𝑛 = 𝑤𝑚 ∧ 𝑖𝑛 ≠ 𝑖𝑚 0, 𝑖𝑓 𝑤𝑛 = 𝑤𝑚 ∧ 𝑖𝑛 = 𝑖𝑚
𝑐𝑜 𝑤𝑛 ,𝑤𝑚 , 𝑜𝑡ℎ𝑒𝑟𝑤𝑖𝑠𝑒
0%
5%
10%
15%
20%
25%
+ Graph. Model + Social Semantics + Body parts
Gain @ 3% training
… for each block …
LBP
LBP